Patent Publication Number: US-9851652-B2

Title: Insert molded bearing for a rotatable component of an image forming device

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 62/270,080, filed Dec. 21, 2015, entitled “Insert Molded Bearing fix a Rotatable Component of an Image Forming Device,” the content of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to image forming devices and more particularly to an insert molded bearing for a rotatable component of an image forming device. 
     2. Description of the Related Art 
     Various rotatable components of an electrophotographic image forming device require an applied voltage to function properly. One example of such a component that requires an applied voltage is a charge roll that charges the surface of a photoconductive drum. Intermittent or total loss of electrical contact to the charge roll can result in severe print detects visible to the user. The electrical path to the charge roll is typically provided through bearings that support the axial ends of a shaft of the charge roll. One approach is to use an electrically conductive plastic bearing connected to a metal compression spring that contacts an electrically conductive contact pad. However, conductive plastics are highly sensitive to the molding process used to form the bearing. If the conductive agent is not evenly and properly dispersed throughout the part, conductive plastics can have variable and overall high resistance values that can lead to print defects. Creepage and clearance concerns must also be addressed when using conductive plastic due to the relatively high voltage nature of charging. A typical area of concern is the proximity of the conductive plastic charge roll bearing to other components, such as the photoconductive drum. Insufficient distance can result in arcing between the charge roll bearing and the photoconductive drum, causing a print defect referred to as black line shorts. 
     Another approach is to provide electrical contact to the charge roll through a metal bearing that supports the axial end of the shaft of the charge roll and that is snap-fitted or slid into a. nonconductive plastic shell that encapsulates the metal bearing in order to shield the metal bearing from the photoconductive drum. This approach reduces the risk of arcing between the charge roll bearing and the photoconductive drum but also increases the cost and complexity of the bearing assembly in comparison with an electrically conductive plastic bearing. 
     Instead of providing electrical contact to the charge roll through the charge roll bearing, another approach is to provide electrical contact to the shaft of the charge roll independent of the charge roll bearing, such as through a cantilevered sheet metal spring that touches the end of the shaft of the charge roll. This approach reduces the risk of arcing between the charge roll and the photoconductive drum. However, connections to the end of the shaft of the charge roll typically require additional space compared to the use of a conductive charge roll bearing, which conflicts with consumer preferences for smaller image forming devices. 
     Accordingly, an improved bearing capable of providing electrical contact to a rotatable component, such as a charge roll, is desired. 
     SUMMARY 
     An assembly for an electrophotographic image forming device according to one example embodiment includes a photoconductive drum having an outer surface and a charge roll. having an outer surface in contact with the outer surface of the photoconductive drum. The charge roll has a shaft that includes a pair of axial ends. A charge roll bearing includes an electrically conductive metal bearing insert molded into an electrically nonconductive plastic shell. The metal bearing includes a bearing surface that rotatably supports one of the pair of axial ends of the shaft. The plastic shell encapsulates all portions of the metal bearing that are positioned adjacent to the photoconductive drum such that the plastic shell shields the metal bearing from electrical arcing with the photoconductive drum. 
     An assembly for an electrophotographic image forming device according to another example embodiment includes a photoconductive drum having an outer surface and a charge roll having an outer surface in contact with the outer surface of the photoconductive drum. The charge roll has a shaft that includes a pair of axial ends. A charge roll bearing includes an electrically conductive metal bearing insert molded into an electrically nonconductive plastic shell. The metal bearing includes a bearing surface that rotatably supports one of the pair of axial ends of the shaft. The plastic shell covers an entire outer circumferential surface of the metal bearing that is proximate to the photoconductive drum and an inner axial side of the metal bearing is inset from an inner axial side of the plastic shell such that the plastic shell shields the metal bearing from electrical arcing with the photoconductive drum. 
     A bearing assembly for supporting a rotatable component of an electrophotographic image forming device according to one example embodiment includes a metal bearing insert molded into an electrically nonconductive plastic shell. The metal bearing includes a bearing surface that defines a cylindrical opening for receiving an axial end of a shaft. to The plastic shell covers an entire outer circumferential surface of the metal bearing and an inner axial side of a portion of the metal bearing forming the opening is inset from an inner axial side of the plastic shell such that the plastic shell shields the metal bearing from electrical arcing. 
    
    
     
       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 depiction of an imaging system according to one example embodiment. 
         FIG. 2  is a schematic diagram of an image forming device according to one example embodiment. 
         FIG. 3  is a perspective view of an imaging unit including a developer unit and a photoconductor unit according to one example embodiment. 
         FIG. 4  is a perspective view of the imaging unit showing the developer unit separated from the photoconductor unit according to one example embodiment. 
         FIG. 5  is a front elevation view of a charge roll assembly of the photoconductor unit according to one example embodiment. 
         FIG. 6  is an inner axial elevation view of a charge roll bearing of the charge roll assembly according to one example embodiment, 
         FIG. 7  is an outer axial elevation view of the charge roll bearing shown in  FIG. 6 . 
         FIG. 8  is a cross-sectional view of the charge roll bearing shown in  FIGS. 6 and 7  taken along line  8 - 8  in  FIG. 7 . 
         FIG. 9  is an inner axial elevation view of the charge roll bearing shown in  FIGS. 6-8  with a charge roll cleaner roll bearing mounted thereon according to one example embodiment. 
         FIG. 10  is a cross-sectional view of the charge roll assembly showing the proximity of the charge roll bearing to a photoconductive drum according to one example embodiment. 
         FIG. 11  is a top perspective view the charge roll assembly mounted on the photoconductor unit housing 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 ear 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 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. 
     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. 
     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. 
     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 unit(s)  300 , respectively. Controller  102  processes print and scan data and operates print engine  110  during printing and scanner system  150  during scanning. 
     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. 
     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 . 
     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. 
       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 , rear  174  and a pair of sides (one facing out of the page and one facing into the page as viewed in  FIG. 2 ). 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. 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 . 
     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 , which are 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  contain yellow, cyan, magenta and black toner, respectively. 
     In the example embodiment illustrated, image forming device  100  utilizes what is commonly referred to as a dual component development system. Each imaging unit  300  includes a reservoir  302  that stores a mixture of toner and magnetic carrier beads. The 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 carrier beads are mixed in reservoir  302 . Reservoir  302  and a magnetic roll  306  collectively form a developer unit. Magnetic roll  306  includes a stationary core that includes one or more permanent magnets and a rotatable sleeve that encircles the core. Reservoir  302  may include toner agitators, such as paddles, augers, etc., that stir the developer mix and present the developer mix to magnetic roll  306 , Each imaging unit  300  also includes a charge roll  308 , a photoconductive drum (PC drum)  310  and a cleaner blade (not shown) that collectively form a photoconductor unit. PC drums  310  are mounted 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. 
     Each charge roll  308  forms a nip with the corresponding PC drum  310 . During a print operation, charge 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. The permanent magnet(s) of magnetic roll  306  attract the carrier beads in reservoir  302  having toner thereon to the outer surface of the sleeve of magnetic roll  306 . The sleeve of magnetic roll  306  transports the carrier beads having toner thereon past a trim bar that trims the mix of carrier beads and toner to a predetermined average height on the outer surface of the sleeve. The sleeve of magnetic roll  306  then transports the carrier heads having toner thereon to the corresponding PC drum  310 . Electrostatic forces from the latent image on PC drum  310  strip the toner from the carrier beads to form a toner image on the surface of PC drum  310 . 
     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 respective first transfer nip  197 . In one embodiment, a positive voltage field attracts the toner images 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 . The cleaner blade/roll removes any toner remnants on PC drum  310  so that the surface of PC drum  310  may be charged and developed with toner again. 
     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 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. 
     While the example image forming device  100  shown in  FIG. 2  illustrates four toner cartridges  200  and four corresponding imaging units  300 , it will be appreciated that a monocolor image forming device  100  may include a single toner cartridge  200  and corresponding imaging unit  300  as compared to a multicolor image forming device  100  that may include multiple toner cartridges  200  and imaging units  300 . Further, although image forming device  100  utilizes ITM  190  to transfer toner to the media, toner may be applied directly to the media by the one or more photoconductive drums  310  as is known in the art. 
     While the example image forming device  100  shown in  FIG. 2  utilizes a dual component development system, in another embodiment, image forming device  100  utilizes what is commonly referred to as a single component development system. In this embodiment, a toner adder roll in each developer unit has an outer surface that is in contact with and forms a nip with the outer surface of a corresponding developer roll. As the toner adder roll and the developer roll rotate, the toner adder roll supplies toner in reservoir  302  to the developer roll. The developer roll is electrically charged and electrostatically attracts the toner particles supplied by the toner adder roll. A doctor blade positioned along each developer roll provides a substantially uniform layer of toner on the developer roll. The outer surface of the developer roll is also in contact with and forms a nip with the outer surface of a corresponding PC drum  310 . As the developer roll and PC drum  310  rotate, toner particles are electrostatically transferred from the developer roll to the latent image on PC drum  310  forming a toned image on the surface of PC drum  310 . PC drum  310  is charged by charge roll  308  and cleaned by a cleaner blade as discussed above. 
       FIGS. 3 and 4  show imaging unit  300  according to one example embodiment. Imaging unit  300  includes a developer unit  320  and a photoconductor unit (PC unit)  330 . In the example embodiment illustrated, developer unit  320  is removably coupled to PC unit  330  to permit repair or replacement of developer unit  320  independent of PC unit  330  and vice versa. In other embodiments, developer unit  320  and PC unit  330  are fixed together such that imaging unit  300  is replaced as a single unit. In the example embodiment illustrated, developer unit  320  and PC unit  330  are replaced independent of toner cartridge  200 . In other embodiments, toner cartridge  200 , developer unit  320  and PC unit  330  are replaced as a single unit. Additional configurations of toner cartridge  200 , developer unit  320  and PC unit  330  may be used as desired. PC unit  330  includes a housing  332  having PC drum  310  as well as charge roll  308  and a cleaner blade mounted thereto. Housing  332  extends generally along a rotational axis  311  of PC drum  310 . Housing  332  may also include one or more user-actuated latches  334  that couple developer unit  320  to PC unit  330  as shown in  FIG. 3  for operation in image forming device  100  and that permit a user to separate developer unit  320  from PC unit  330  when imaging unit  300  is removed from image forming device  100  as shown in  FIG. 4 . Developer unit  320  includes a housing  322  having reservoir  302  therein. Housing  322  extends generally along a rotational axis of magnetic roll  306 , which is substantially parallel to rotational axis  311  of PC drum  310 . A portion of magnetic roll  306  is exposed from reservoir  302  at one side of housing  322  for mating with PC drum  310  when developer unit  320  is coupled to PC unit  330 . When developer unit  320  is coupled to PC unit  330 , imaging unit  300  is insertable into image forming device  100  via a sliding motion along an insertion direction  326  as indicated in  FIG. 3 . 
       FIG. 5  shows a charge roll assembly  340  of PC unit  330  according to one example embodiment. Charge roll assembly  340  includes charge roll  308  and may include a charge roll cleaner roll  342 . An outer surface of charge roll cleaner roll  342  is in contact with the outer surface of charge roll  308  in order to remove toner particles and other contaminants from the outer surface of charge roll  308 . Charge roll  308  includes a rotatable shaft  309  and charge roll cleaner roll  342  includes a rotatable shaft  343  that is parallel to shaft  309 . A composite charge roll bearing  350  is positioned at each axial end of charge roll  308 . Each charge roll bearing  350  receives and rotatably supports a respective axial end of shaft  309 . 
       FIGS. 6-9  show charge roll bearing  350  according to one example embodiment. Charge roll bearing  350  includes an inner axial side  352  that faces inward axially relative to charge roll  308  and an outer axial side  354  that faces outward axially relative to charge roll  308 . Charge roll bearing  350  includes an electrically conductive metal beating  356 , which may be composed of, e.g., sintered bronze, that is insert molded into an electrically nonconductive plastic shell  358 . Together, metal bearing  356  and plastic shell  358  form charge roll bearing  350 . Metal bearing  356  includes a cylindrical opening  360  that receives shaft  309 . Opening  360  is formed by a bearing surface  362  that guides and supports the rotation of a respective axial end of shaft  309 . Plastic shell  358  includes a cylindrical opening  361  that is aligned with opening  360  in order to permit shaft  309  to enter opening  360  and contact bearing surface  362 . In the embodiment illustrated, metal bearing  356  includes a tab  364  extending therefrom that receives an electrically conductive compression spring  366 , Spring  366  provides an electrical path to metal bearing  356  and biases charge roll bearing  350  toward PC drum  310  when charge roll assembly  340  is installed in PC unit  330 . 
     In the embodiment illustrated, shell  358  includes a pocket  368  formed on inner axial side  352  of charge roll bearing  350 . With reference to  FIGS. 8 and 9 , in the embodiment illustrated, a charge roll cleaner roll bearing  370  is slidably positioned (vertically as viewed in  FIG. 9 ) in pocket  368 . Charge roll cleaner roll bearing  370  includes an opening  372  that receives shaft  343  of charge roll cleaner roll  342 , Opening  372  is formed by a bearing surface  374  that guides and supports the rotation of shaft  343 . In one embodiment, bearing  370  is composed of electrically nonconductive plastic. In the embodiment illustrated, bearing  370  includes a tab  376  extending therefrom that receives a compression spring  378 . Spring  378  is positioned in pocket  368  and biases bearing  370  toward charge roll  308 . 
       FIG. 10  shows the positioning of charge roll  308  and charge roll bearing  350  relative to PC drum  310 , which is illustrated schematically. The nonconductive nature of plastic shell  358  insulates metal bearing  356  from PC drum  310  and thereby reduces the risk of arcing between metal bearing  356  and PC drum  310 . Plastic shell  358  encapsulates all portions of metal bearing  356  that are positioned adjacent to PC drum  310 , thereby shielding metal bearing  356  from PC drum  310 . For example, plastic shell  358  covers the entire outer circumferential surface  363  of metal bearing  356  that is proximate to PC drum  310 . Further, as shown in  FIG. 8 , an inner axial side  356   a  of metal bearing  356  is inset from an inner axial side  358   a  of plastic shell  358  and an outer axial side  356   b  of metal bearing  356  is inset from an outer axial side  358   b  of plastic shell  358 . In this manner, the inner and outer axial edges of opening  360  in metal bearing  356  are inset from inner and outer axial edges of opening  361  in plastic shell  358 . 
     Without the shielding provided by plastic shell  358  between metal bearing  356  and PC drum  310 , the high voltage required for charging could create an arcing risk across the relatively small distance between metal bearing  356  and PC drum  310 . 
     The plastic construction of shell  358  also provides a greater range of geometries available for charge roll bearing  350  in comparison with a metal bearing, due to greater flexibility in the molding of plastic as opposed to metal. For example, the plastic construction of shell  358  permits the inclusion of pocket  368 , allowing charge roll bearing  350  to support charge roll cleaner roll bearing  370 . With reference to  FIG. 11 , in one embodiment, plastic shell  358  also includes locating ribs  380  on its outer surface that engage corresponding rails  336  on housing  332  when charge roll assembly  340  is installed on PC unit  330 . The engagement between ribs  380  and rails  336  controls the translational and rotational degrees of freedom of charge roll bearing  350 . 
     Further, insert molding metal bearing  356  into plastic shell  358  simplifies the assembly of charge roll bearing  350  in comparison with a charge roll bearing that includes a metal hearing that is snap-fitted or slid into a plastic shell. Insert molding metal bearing  356  into plastic shell  358  also ensures that metal hearing  356  will not separate from plastic shell  358 . 
     In some embodiments, when metal bearing  356  is molded into plastic shell  358 , the high temperatures associated with the molding process cause oil migration out of metal bearing  356 . If the oil migration is left unaddressed, plastic shell  358  may have a substantial amount of oil coating its outer surfaces, which risks contaminating and damaging other imaging components (e.g., crazing of PC drum  310 ). In order to address the risk of oil migration, in some embodiments, metal bearing  356  is soaked in a degreaser prior to molding plastic shell  358 , This minimizes the net amount of oil that ends up on the outer surfaces of plastic shell  358 . The application of degreaser must be balanced with the desire to maintain a minimum acceptable level of oil in the final metal bearing  356  to provide a functional bearing surface  362 . 
     Accordingly, the present disclosure describes a bearing that includes an electrically conductive metal bearing that is insert molded into a nonconductive plastic shell. The metal bearing provides a robust conductive path to the charge roll shaft and the plastic serves as an insulative barrier between the charge roll shaft and the photoconductive drum, while still allowing complex geometry to be integrated into the part. While the example discussed above includes a bearing for a charge roll, it will be appreciated that a composite bearing that includes a metal bearing insert molded into a nonconductive plastic shell may be used to support and provide an electrical path to other rotatable components with the image forming device as desired. 
     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.