Abstract:
An assembly for an electrophotographic image forming device according to one example embodiment includes a charge roll and a bracket that extends along an axial length of the charge roll. First and second bearing retainers are positioned on a first axial end and a second axial end of the bracket, respectively. First and second bearings are pivotally mounted to the first and second bearing retainers, respectively. Each of the first and second bearings has a charge roll opening that supports a respective axial end of a shaft of the charge roll. First and second biasing members act on the first and second bearings, respectively. The first and second biasing members bias the charge roll toward an operative position for charging a photoconductive drum. A direction of force from the first biasing member on the first bearing and from the second biasing member on the second bearing is toward the bracket.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     None. 
     BACKGROUND 
     1. Field of the Disclosure 
     The present invention relates generally to electrophotographic image forming devices and more particularly to a charge roll mounting assembly for an electrophotographic image forming device. 
     2. Description of the Related Art 
     As is well known in the art, during a print operation by an electrophotographic image forming device a charge roll charges the surface of a photoconductive drum to a predetermined voltage. The charged surface of the photoconductive drum is then selectively exposed to a laser light source to selectively discharge the surface of the photoconductive drum and form an electrostatic latent image on the photoconductive drum corresponding to the image being printed. Toner is picked up by the latent image on the photoconductive drum from a developer roll (in the case of single component development printing) or a magnetic roll (in the case of dual component development printing) creating a toned image on the surface of the photoconductive drum. The toned image is then transferred from the photoconductive drum to the print media either directly by the photoconductive drum or indirectly by an intermediate transfer member. A cleaning blade or roller removes any residual toner adhering to the photoconductive drum after the toner is transferred from the photoconductive drum. The cleaned surface of the photoconductive drum is then ready to be charged again and exposed to the laser light source to continue the printing cycle. 
     The charge roll is preferably biased uniformly along the axial length of the charge roll against the surface of the photoconductive drum to provide uniform charging across the axial length of the photoconductive drum. If the charge roll bias is uneven, print defects may occur. For example, if the charge roll does not make enough contact at the axial ends of the photoconductive drum for proper charging, dark spots will occur at the edges of the printed page. On the other hand, if the charge roll has too much bias at the axial ends of the photoconductive drum, light or feathered printing will occur at the edges of the printed page. The charge roll is often driven by friction from the nip formed between the charge roll and the photoconductive drum. If the nip force is too low, the charge roll may slip against the surface of the photoconductive drum resulting in dark bands on the printed page. During long periods of inactivity, such as during shipping or storage of the image forming device or a replaceable unit containing the charge roll and photoconductive drum, a flat spot may be formed on the surface of the charge roll where it contacts the photoconductive drum due to compression of the charge roll at that location. When printing resumes, the flat spot causes a temporary spike in the load to the charge roll that can&#39;t be overcome if the nip force is too low until after the image forming device operates long enough for the charge roll to regain its original shape. Further, excessive vibration of the charge roll during operation may cause light or dark bands on the printed page as a result of the charge roll momentarily having a bias that is too high or too low as it vibrates. 
       FIGS. 1 and 2  show a prior art charge roll mounting assembly  20 . Assembly  20  includes a cleaner bracket  22  having a rear plate  24  and a top plate  26  that each extend in a lengthwise direction  28  corresponding with the axial direction of the photoconductive drum ( FIG. 3 ). Top plate  26  extends forward and upward from rear plate  24 . Rear plate  24  and top plate  26  are formed integrally with each other from electrogalvanized steel sheet. A cleaner blade  30  extends in a cantilevered manner downward from rear plate  24 . A free end  32  of cleaner blade  30  is positioned to contact the surface of the photoconductive drum to remove residual toner from the photoconductive drum. 
     A charge roll  34  is mounted to cleaner bracket  22  in position to contact the surface of the photoconductive drum to charge the surface of the photoconductive drum. A cleaner roll  36  is mounted against charge roll  34  to clean toner from the surface of charge roll  34 . Charge roll  34  includes a shaft  35  and cleaner roll  36  includes a shaft  37 . Cleaner roll  36  is driven by friction from the nip formed between charge roll  34  and cleaner roll  36 . The axial ends of shafts  35  and  37  are retained by bearings  38 A,  38 B. Specifically, each bearing  38 A,  38 B includes a charge roll opening  40 A,  40 B that receives an axial end of shaft  35  and a cleaner roll opening  42 A,  42 B that receives an axial end of shaft  37 . Openings  40 A,  40 B,  42 A,  42 B are generally cylindrical in shape and formed by bearing surfaces for shafts  35  and  37  of charge roll  34  and cleaner roll  36  to rotate against. The distance between openings  40 A and  42 A and between openings  40 B and  42 B define the positional relationship between charge roll  34  and cleaner roll  36  to achieve the desired nip force between charge roll  34  and cleaner roll  36 . Cleaner roll openings  42 A,  42 B are spaced axially inward from charge roll openings  40 A,  40 B due to the shaft of cleaner roll  36  having a shorter length than the shaft of charge roll  34 . 
     A cast zinc bearing retainer  44 A,  44 B mounts each bearing  38 A,  38 B to cleaner bracket  22  on inner axial sides of bearing retainers  44 A,  44 B. Each bearing retainer  44 A,  44 B includes a rectangular slot  46 A,  46 B that slips over a corresponding flange  48 A,  48 B formed at each end of top plate  26  to align bearing retainers  44 A,  44 B with cleaner bracket  22 . Bearing retainers  44 A,  44 B and rear plate  24  of cleaner bracket  22  have corresponding screw holes  50 A,  50 B and  52 A,  52 B that receive a screw at each end of cleaner bracket  22  to fix bearing retainers  44 A,  44 B to cleaner bracket  22  and cleaner bracket  22  to a housing of the image forming device or a housing of a replaceable unit of the image forming device. Bearing retainer  44 B includes a fixed pin  56  that extends axially inward that retains bearing  38 B on bearing retainer  44 B. Bearing retainer  44 A includes a guide slot  58  in substantially the same position on bearing retainer  44 A as pin  56  on bearing retainer  44 B. Guide slot  58  receives a locking pin  60  that retains bearing  38 A on bearing retainer  44 A as discussed in greater detail below. 
       FIG. 3  shows an end view of bearing  38 A positioned relative to cleaner bracket  22  with bearing retainer  44 A removed to more clearly illustrate the features of bearing  38 A. Bearing  38 B is substantially the same as bearing  38 A except that bearing  38 B is a mirror image of bearing  38 A. Each bearing  38 A,  38 B includes an arm  62  that extends forward, away from rear plate  24 , from the portion of the bearing  38 A,  38 B that forms charge roll opening  40 A,  40 B. An opening  64  is formed in a distal end of arm  62 . Opening  64  of bearing  38 B receives pin  56  of bearing retainer  44 B and opening  64  of bearing  38 A receives locking pin  60 . Each bearing  38 A,  38 B is pivotally mounted to its bearing retainer  44 A,  44 B and cleaner bracket  22  about a pivot point  66  at the center of opening  64 . A compression spring  68 A,  68 B is positioned between each flange  48 A,  48 B of top plate  26  and a ledge  70  formed on a top surface of arm  62 . Each ledge  70  includes a small finger  72  extending from ledge  70  that fits inside the end of compression spring  68 A,  68 B that is positioned against ledge  70  to position the end of compression spring  68 A,  68 B nearest ledge  70 . A spring screw  74 A,  74 B passes through a screw hole  76 A,  76 B in each flange  48 A,  48 B and into the end of compression spring  68 A,  68 B that is positioned against flange  48 A,  48 B to position the end of compression spring  68 A,  68 B nearest flange  48 A,  48 B. Compression springs  68 A,  68 B bias bearings  38 A,  38 B about pivot point  66  toward a photoconductive drum  33  (in a counterclockwise direction as viewed in  FIG. 3 ). Charge roll  34  and cleaner roll  36  move about pivot point  66  as a result of their engagement with charge roll openings  40 A,  40 B and cleaner roll openings  42 A,  42 B of bearings  38 A,  38 B. In this manner, the force from compression springs  68 A,  68 B biases charge roll  34  against photoconductive drum  33 . 
     When charge roll mounting assembly  20  is installed in the image forming device and positioned relative to photoconductive drum  33 , photoconductive drum  33  applies a force on charge roll  34  in the direction of the arrow  78  shown in  FIG. 3 . The force from photoconductive drum  33  on charge roll  34  compresses compression springs  68 A,  68 B from their home positions causing bearings  38 A,  38 B to pivot away from photoconductive drum  33  (in the clockwise direction as viewed in  FIG. 3 ), in turn, displacing charge roll  34  from its home position to a position biased against the outer surface of photoconductive drum  33 . 
       FIG. 4  shows locking pin  60  in greater detail. Locking pin  60  includes a handle  80  that includes a relatively wide base  82  and a narrower flange  84  that extends from base  82 . A rectangular prism shaped rod  86  extends away from base  82  of handle  80  in a direction generally orthogonal to handle  80 . The rectangular cross section of rod  86  is defined by a height and a width. The height is too large to fit through a channel  59  at the front of bearing retainer  44 A that forms an entrance to guide slot  58  but the width is small enough to pass through channel  59  in order to permit locking pin  60  to be removed from bearing retainer  44 A as discussed below. Rod  86  leads to a cylindrical spacer  88 . A cylindrical pin  90  extends from spacer  88  away from handle  80 . Spacer  88  is concentric with rod  86  and pin  90  and has a diameter that is larger than the height and width of rod  86  and the diameter of pin  90 . The portion of spacer  88  that extends radially beyond the outer surface of rod  86  is spaced from handle  80  by the length of rod  86  in the axial direction of charge roll  34 . A retaining bump  92  extends slightly outward from flange  84  in the same direction as rod  86  and pin  90 . With reference to  FIGS. 1-4 , pin  90  is positioned in opening  64  on arm  62  of bearing  38 A. The engagement between pin  90  and opening  64  of bearing  38 A controls the position of pivot point  66  of bearing  38 A relative to bearing retainer  44 A. Rod  86  is positioned in guide slot  58  of bearing retainer  44 A with bearing retainer  44 A sandwiched between spacer  88  and base  82  of handle  80  to position locking pin  60  axially relative to bearing retainer  44 A. Retaining bump  92  extends into a corresponding opening  94  in bearing retainer  44 A that is positioned above guide slot  58 . The engagement between positioning bump  92  and opening  94  prevents locking pin  60  from rotating relative to bearing retainer  44 A. When positioning bump  92  is positioned in opening  94 , rod  86  is oriented with its height aligned with channel  59  such that rod  86  cannot slide out of guide slot  58  and locking pin  60  cannot separate from bearing retainer  44 A. 
     Locking pin  60  is manually installable onto and removable from charge roll mounting assembly  20  to aid in the installation and removal of charge roll  34  and cleaner roll  36  onto and off of cleaner bracket  22 . To remove locking pin  60 , a user pulls flange  84  of handle  80  away from bearing retainer  44 A until positioning bump  92  pulls out of opening  94 . Locking pin  60  is then free to rotate relative to bearing retainer  44 A until the width of rod  86  is aligned with channel  59  so that rod  86  can slide out of guide slot  58  and locking pin  60  can separate from bearing retainer  44 A. Pin  90  can then be removed from opening  64  on arm  62  of bearing  38 A. To reengage locking pin  60  with bearing  38 A, this sequence is reversed. 
     SUMMARY 
     An assembly for an electrophotographic image forming device according to one example embodiment includes a charge roll having a shaft that includes a pair of axial ends. The charge roll has an axial length between the axial ends of the shaft. A bracket extends along the axial length of the charge roll. A first bearing retainer is positioned on a first axial end of the bracket and a second bearing retainer is positioned on a second axial end of the bracket. A first bearing is pivotally mounted to the first bearing retainer and a second bearing is pivotally mounted to the second bearing retainer. Each of the first and second bearings has a charge roll opening that supports a respective axial end of the shaft of the charge roll. A first biasing member acts on the first bearing and a second biasing member acts on the second bearing. The first and second biasing members bias the charge roll toward an operative position for charging an outer surface of a photoconductive drum. A direction of force from the first biasing member on the first bearing and from the second biasing member on the second bearing is toward the bracket. 
     An assembly for an electrophotographic image forming device according to another example embodiment includes a photoconductive drum and a charge roll having a shaft that includes a pair of axial ends. The charge roll has an axial length between the axial ends of the shaft. A bracket extends along the axial length of the charge roll. The bracket has a rear plate positioned rearward from the charge roll and a top plate positioned above the charge roll. The top plate extends from a top portion of the rear plate in a forward direction away from the rear plate. A first bearing retainer is positioned on a first axial end of the bracket and a second bearing retainer is positioned on a second axial end of the bracket. A first bearing is pivotally mounted to the first bearing retainer and positioned on an inner axial side of the first bearing retainer and a second bearing is pivotally mounted to the second bearing retainer and positioned on an inner axial side of the second bearing retainer. Each of the first and second bearings has a charge roll opening that supports a respective axial end of the shaft of the charge roll. A first biasing member is in contact with the first bearing and a second biasing member is in contact with the second bearing. The first and second biasing members bias the charge roll toward an outer surface of the photoconductive drum. A direction of force from the first biasing member on the first bearing and from the second biasing member on the second bearing is toward the rear plate. 
    
    
     
       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 perspective view of a prior art charge roll mounting assembly. 
         FIG. 2  is an exploded view of the prior art charge roll mounting assembly shown in  FIG. 1 . 
         FIG. 3  is an end view of a bearing of the prior art charge roll mounting assembly shown in  FIG. 1  positioned relative to the cleaner bracket. 
         FIG. 4  is a perspective view of a locking pin of the prior art charge roll mounting assembly shown in  FIG. 1 . 
         FIG. 5  is a perspective view of a charge roll mounting assembly according to one example embodiment. 
         FIG. 6  is an exploded view of the charge roll mounting assembly shown in  FIG. 5 . 
         FIG. 7  is an end view of a bearing of the charge roll mounting assembly shown in  FIG. 5  positioned relative to the cleaner bracket. 
         FIG. 8  is a perspective view of a locking pin of the charge roll mounting assembly shown in  FIG. 5 . 
         FIG. 9  is a perspective view of a charge roll mounting assembly according to another example embodiment. 
         FIG. 10  is an end view of a bearing of the charge roll mounting assembly shown in  FIG. 9  positioned relative to a cleaner bracket. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the accompanying drawings where like numerals represent like elements. The embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure. It is to be understood that other embodiments may be utilized and that process, electrical, and mechanical changes, etc., may be made without departing from the scope of the present disclosure. Examples merely typify possible variations. Portions and features of some embodiments may be included in or substituted for those of others. The following description, therefore, is not to be taken in a limiting sense and the scope of the present disclosure is defined only by the appended claims and their equivalents. 
       FIGS. 5 and 6  show a charge roll mounting assembly  120  according to one example embodiment. Assembly  120  includes a cleaner bracket  122  having a rear plate  124  and a top plate  126  that each extend in a lengthwise direction  128  corresponding with the axial direction of the photoconductive drum ( FIG. 7 ). Top plate  126  extends forward and upward from rear plate  124 . Rear plate  124  has screw holes  152  that receive a screw at each end of cleaner bracket  122  to fix cleaner bracket  122  to a housing of the image forming device or a housing of a replaceable unit of the image forming device (the screw hole  152  at the right end of rear plate  124  as viewed in  FIG. 6  is obscured but is substantially the same as the screw hole  152  shown at the left end of rear plate  124 ). A cleaner blade  130  extends in a cantilevered manner downward from rear plate  124 . A free end  132  of cleaner blade  130  is positioned to contact the surface of the photoconductive drum to remove residual toner from the photoconductive drum. 
     A charge roll  134  is mounted to cleaner bracket  122  in position to contact the surface of the photoconductive drum to charge the surface of the photoconductive drum. A cleaner roll  136  is mounted against charge roll  134  to clean toner from the surface of charge roll  134 . Charge roll  134  includes a shaft  135  and cleaner roll  136  includes a shaft  137 . Cleaner roll  136  is driven by friction from the nip formed between charge roll  134  and cleaner roll  136 . The axial ends of shafts  135  and  137  are retained by bearings  138 A,  138 B. Bearings  138 A,  138 B may be composed of a suitable bearing plastic. Specifically, each bearing  138 A,  138 B includes a charge roll opening  140 A,  140 B that receives an axial end of shaft  135  and a cleaner roll opening  142 A,  142 B that receives an axial end of shaft  137 . Openings  140 A,  140 B,  142 A,  142 B are generally cylindrical in shape and formed by bearing surfaces for shafts  135  and  137  of charge roll  134  and cleaner roll  136  to rotate against. The distance between openings  140 A and  142 A and between openings  140 B and  142 B define the positional relationship between charge roll  134  and cleaner roll  136  to achieve the desired nip force between charge roll  134  and cleaner roll  136 . Cleaner roll openings  142 A,  142 B are spaced axially inward from charge roll openings  140 A,  140 B due to the shaft of cleaner roll  136  having a shorter length than the shaft of charge roll  134 . 
     Top plate  126  includes a flange  148 A,  148 B at each end that extends forward and upward from top plate  126 . A distal end of each flange  148 A,  148 B includes a mounting tab  149 A,  149 B that curves downward and forward as it advances away from top plate  126 . A screw hole  176 A,  176 B is formed in each tab  149 A,  149 B. A bearing retainer  144 A,  144 B extends downward from an outer axial side of each flange  148 A,  148 B. In this embodiment, rear plate  124 , top plate  126 , including flanges  148 A,  148 B and tabs  149 A,  149 B, and bearing retainers  144 A,  144 B are formed integrally from a suitable metal such as electrogalvanized steel sheet. Bearing retainers  144 A,  144 B mount bearings  138 A,  138 B to cleaner bracket  122  on inner axial sides of bearing retainers  144 A,  144 B. Bearing retainers  144 A,  144 B each include a guide slot  158 A,  158 B that receives a corresponding locking pin  160 A,  160 B that retains bearings  138 A,  138 B on bearing retainers  144 A,  144 B as discussed in greater detail below. 
       FIG. 7  shows an end view of bearing  138 A positioned relative to cleaner bracket  122  with bearing retainer  144 A removed to more clearly illustrate the features of bearing  138 A. Bearing  138 B is substantially the same as bearing  138 A except that bearing  138 B is a mirror image of bearing  138 A. Each bearing  138 A,  138 B includes an arm  162  that extends forward, away from rear plate  124 , from the portion of the bearing  138 A,  138 B that forms charge roll opening  140 A,  140 B. An opening  164  is formed in a distal end of arm  162 . Opening  164  of each bearing  138 A,  138 B receives the corresponding locking pin  160 A,  160 B. Each bearing  138 A,  138 B is pivotally mounted to its bearing retainer  144 A,  144 B of cleaner bracket  122  about a pivot point  166  at the center of opening  164 . Each bearing  138 A,  138 B includes a flange  163  that extends upward from the portion of the bearing  138 A,  138 B that forms charge roll opening  140 A,  140 B in a position next to and axially outward from the cleaner roll opening  142 A,  142 B. Each flange  163  includes a ledge  170  formed on a front face thereof above charge roll opening  140 A,  140 B. A compression spring  168 A,  168 B is positioned between distal end  149 A,  149 B of each flange  148 A,  148 B of top plate  126  and ledge  170  formed on flange  163  of bearings  138 A,  138 B. Each ledge  170  includes a small finger  172  extending from the front face of ledge  170  that fits inside the end of compression spring  168 A,  168 B that is positioned against ledge  170  to position the end of compression spring  168 A,  168 B nearest ledge  170 . A spring screw  174 A,  174 B passes through screw hole  176 A,  176 B in each flange  148 A,  148 B at distal ends  149 A,  149 B of flanges  148 A,  148 B and into the end of compression spring  168 A,  168 B that is positioned against flange  148 A,  148 B to position the end of compression spring  168 A,  168 B nearest flange  148 A,  148 B. Compression springs  168 A,  168 B bias bearings  138 A,  138 B about pivot point  166  toward a photoconductive drum  133  (in a counterclockwise direction as viewed in  FIG. 7 ). Charge roll  134  and cleaner roll  136  move about pivot point  166  as a result of their engagement with charge roll openings  140 A,  140 B and cleaner roll openings  142 A,  142 B of bearings  138 A,  138 B. In this manner, the force from compression springs  168 A,  168 B biases charge roll  134  against photoconductive drum  133 . 
     When charge roll mounting assembly  120  is installed in the image forming device and positioned relative to photoconductive drum  133 , photoconductive drum  133  applies a force on charge roll  134  in the direction of the arrow  178  shown in  FIG. 7 . The force from photoconductive drum  133  on charge roll  134  compresses compression springs  168 A,  168 B from their home positions causing bearings  138 A,  138 B to pivot away from photoconductive drum  133  (in the clockwise direction as viewed in  FIG. 7 ), in turn, displacing charge roll  134  from its home position to a position biased against the outer surface of photoconductive drum  133 . 
     With reference back to  FIG. 3 , in prior art assembly  20 , the direction of the spring force F 1  applied to ledges  70  by compression springs  68 A,  68 B is generally orthogonal to top plate  26  and away from rear plate  24 . A lateral distance x1 between each pivot point  66  and the center of compression springs  68 A,  68 B is relatively small (2.2 mm) resulting in little leverage for compression springs  68 A,  68 B on ledges  70 . As a result, the spring force of compression springs  68 A,  68 B is high in order to achieve sufficient nip force between charge roll  34  and photoconductive drum  33 . The large spring force causes wide variations in the nip force between charge roll  34  and photoconductive drum  33  across multiple units of assembly  20  due to the size tolerances of the components of assembly  20  such as bearings  38 A,  38 B, charge roll  34  and cleaner bracket  22 . In contrast, as shown in  FIG. 7 , the direction of the spring force F 2  applied to ledges  170  by compression springs  168 A,  168 B is generally parallel to top plate  126  and toward rear plate  124 . A lateral distance x2 between each pivot point  166  and the center of compression springs  168 A,  168 B is large in comparison with prior art assembly  20  (e.g., ˜8.1 mm) resulting in significantly more leverage for compression springs  168 A,  168 B on ledges  170  without increasing the overall size of assembly  120  in comparison with prior art assembly  20 . The increased leverage permits a reduction of the spring force of compression springs  168 A,  168 B in comparison with springs  68 A,  68 B. The reduced spring force also reduces the variations in the nip force between charge roll  134  and photoconductive drum  133  across multiple units of assembly  120 . 
     With reference back to  FIG. 2 , zinc bearing retainers  44 A,  44 B of prior art assembly  20  are sufficiently stiff to reduce the vibration of bearings  38 A,  38 B across the wide range of nip forces between charge roll  34  and photoconductive drum  33 ; however, the zinc material of bearing retainers  44 A,  44 B is relatively expensive. With reference to  FIG. 6 , the reduced variation of the nip force between charge roll  134  and photoconductive drum  133  achieved by assembly  120  permits the elimination of the zinc bearing retainers  44 A,  44 B of prior art assembly  20  thereby reducing the cost of manufacture of assembly  120  in comparison with assembly  20 . Bearing retainers  144 A,  144 B formed integrally with cleaner bracket  122  are sufficiently stiff to reduce vibration of bearings  138 A,  138 B. 
       FIG. 8  shows locking pin  160 A in greater detail. Locking pin  160 B is substantially the same as locking pin  160 A. Locking pins  160 A,  160 B may be composed of plastic. Locking pins  160 A,  160 B include a handle  180  that includes a relatively wide base  182  and a narrower flange  184  that extends from base  182 . A rectangular prism shaped rod  186  extends away from base  182  of handle  180  in a direction generally orthogonal to handle  180 . The rectangular cross section of rod  186  is defined by a height and a width. The height is too large to fit through a channel  159 A,  159 B at the front of each bearing retainer  144 A,  144 B that forms an entrance to guide slots  158 A,  158 B but the width is small enough to pass through channel  159 A,  159 B in order to permit locking pin  160 A,  160 B to be removed from its bearing retainer  144 A,  144 B as discussed below. Rod  186  leads to a cylindrical spacer  188 . A cylindrical pin  190  extends from spacer  188  away from handle  180 . Spacer  188  is concentric with rod  186  and pin  190  and has a diameter that is larger than the height and width of rod  186  and the diameter of pin  190 . The portion of spacer  188  that extends radially beyond the outer surface of rod  186  is spaced from handle  180  by the length of rod  186  in the axial direction of charge roll  134 . Flange  184  includes a snout  185  that extends from a distal end of flange  184  and bends slightly away from the direction that rod  186  and pin  190  extend from base  182 . A retaining bump  192  extends slightly outward from flange  184  in the same direction as rod  186  and pin  190 . With reference to  FIGS. 5-8 , pins  190  of locking pins  160 A,  160 B are positioned in openings  164  on arms  162  of bearings  138 A,  138 B. The engagement between pin  190  and opening  164  controls the position of pivot point  166  of each bearing  138 A,  138 B relative to its bearing retainer  144 A,  144 B. Rod  186  of each locking pin  160 A,  160 B is positioned in its guide slot  158 A,  158 B with bearing retainers  144 A,  144 B sandwiched between spacer  188  and base  182  of locking pin  160 A,  160 B to position locking pins  160 A,  160 B axially relative to bearing retainers  144 A,  144 B. Retaining bumps  192  extend into corresponding openings  194 A,  194 B in bearing retainers  144 A,  144 B that are positioned above guide slots  158 A,  158 B. The engagement between positioning bumps  192  and openings  194 A,  194 B prevent locking pins  160 A,  160 B from rotating relative to bearing retainers  144 A,  144 B. When a positioning bump  192  is positioned in an opening  194 A or  194 B, rod  186  is oriented with its height aligned with channel  159 A,  159 B such that rod  186  cannot slide out of guide slot  158 A or  158 B and locking pin  160 A or  160 B cannot separate from bearing retainer  144 A or  144 B. 
     Locking pins  160 A,  160 B are manually installable onto and removable from charge roll mounting assembly  120  to aid in the installation and removal of charge roll  134  and cleaner roll  136  onto and off of cleaner bracket  122 . To remove either locking pin  160 A,  160 B, a user pulls snout  185  of flange  184  of handle  180  away from bearing retainer  144 A or  144 B until positioning bump  192  pulls out of opening  194 A or  194 B. The locking pin  160 A or  160 B is then free to rotate relative to bearing retainer  144 A or  144 B until the width of rod  186  is aligned with channel  159 A or  159 B so that rod  186  can slide out of guide slot  158 A or  158 B and locking pin  160 A or  160 B can separate from bearing retainer  144 A or  144 B. Pin  190  can then be removed from opening  164  on arm  162  of bearing  138 A or  138 B. To reengage locking pin  160 A,  160 B with bearing  138 A,  138 B, this sequence is reversed. In the example embodiment illustrated, locking pins  160 A,  160 B include an alignment tab  196  extending from the bottom of base  182 . Alignment tab  196  provides a visual indicator to the user that locking pin  160 A,  160 B is in its locked position with retaining bump  192  aligned with opening  194 A,  194 B. For example, when retaining bump  192  is aligned with opening  194 A,  194 B, alignment tab  196  may point forward from assembly  120 . In one embodiment, when retaining bump  192  is aligned with opening  194 A,  194 B, alignment tab  196  aligns with a visual indicator on the outer or front side of bearing retainer  144 A,  144 B such as a notch or mark so that the user can install locking pin  160 A,  160 B by aligning alignment tab  196  with the indicator on bearing retainer  144 A,  144 B. 
     Snout  185  provides an improved touch point for the user in comparison with flange  84  of locking pin  60  shown in  FIG. 4 . Specifically, the bend of snout  185  away from bearing retainer  144 A or  144 B allows the user to more easily grasp flange  184 . Further, the edges of retaining bump  192  are sharper (closer to a right angle) than those of retaining bump  92  of assembly  20 , which have a larger radius of curvature. The decreased radius of curvature of the edges of retaining bump  192  makes positioning bump  192  less prone to unintentionally disengage from opening  194 A,  194 B. As a result, the sharper edges of retaining bump  192  make the engagement between retaining bump  192  and opening  194 A,  194 B more secure than the engagement between retaining bump  92  and opening  94  of bearing retainer  44 A while snout  185  makes locking pin  160 A,  160 B more easy to install and remove than locking pin  60  despite the improved engagement between retaining bump  192  and opening  194 A,  194 B. 
       FIG. 9  shows a charge roll mounting assembly  220  according to another example embodiment. Assembly  220  includes a cleaner bracket  222  having a charge roll  234  and a cleaner roll  236  mounted thereto by bearings  238 A,  238 B. Bearings  238 A,  238 B, which retain and support the ends of the shafts of charge roll  234  and cleaner roll  236 , are mounted to bearing retainers  244 A,  244 B formed on the ends of cleaner bracket  222 . Cleaner bracket  222  includes a rear plate  224  and a top plate  226  as discussed above. 
       FIG. 10  shows an end view of bearing  238 A positioned relative to cleaner bracket  222  with bearing retainer  244 A removed to more clearly illustrate the features of bearing  238 A. Bearing  238 B is substantially the same as bearing  238 A except that bearing  238 B is a mirror image of bearing  238 A. Instead of compression springs, a pair of extension springs  268 A,  268 B bias bearings  238 A,  238 B toward a photoconductive drum  233  (in a counterclockwise direction as viewed in  FIG. 10 ) about a pivot point  266 . Each bearing  238 A,  238 B includes a charge roll opening and a cleaner roll opening as discussed above. Each bearing  238 A,  238 B also includes an arm  262  that extends forward, away from rear plate  224  of cleaner bracket  222 , from the portion of the bearing  238 A,  238 B that forms the charge roll opening. An opening  264  is formed in a distal end of each arm  262 . Pivot point  266  is formed at the center of opening  264 . A tab  270  extends upward from a distal end of arm  262  generally perpendicular to a line formed between the center of the charge roll opening and opening  264  in arm  262 . Extension springs  268 A,  268 B are mounted at one end to tab  270  and at another end to rear plate  224 . The force from extension springs  268 A,  268 B biases charge roll  234  against the photoconductive drum. 
     As shown in  FIG. 10 , the direction of the spring force F 3  applied to tabs  270  by extension springs  268 A,  268 B is roughly parallel to top plate  226  and toward rear plate  224 . A lateral distance x3 between each pivot point  266  and the center of extension springs  268 A,  268 B is large in comparison with prior art assembly  20  (e.g., ˜8.7 mm) resulting in significantly more leverage for extension springs  268 A,  268 B on tabs  270 . The increased leverage permits a reduction of the spring force of extension springs  268 A,  268 B in comparison with compression springs  68 A,  68 B. As discussed above, the reduced spring force also reduces the variations in the nip force between charge roll  234  and photoconductive drum  233  across multiple units of assembly  220 . In another embodiment, the charge roll mounting assembly includes a torsion spring or a leaf spring that biases the charge roll against the photoconductive drum. 
     With reference to  FIGS. 9 and 10 , in the embodiment illustrated, each bearing retainer  244 A,  244 B includes an opening that aligns with a corresponding opening  264  of arm  262  of each bearing  238 A,  238 B. A screw  260  passes through the openings of each bearing retainer  244 A,  244 B and bearing  238 A,  238 B to connect each bearing  238 A,  238 B to its respective bearing retainer  244 A,  244 B. Each screw  260  includes a threaded portion proximate to the screw head that attaches screw  260  to its bearing retainer  244 A,  244 B and an unthreaded portion (like pin  190  discussed above) at its distal end that passes through the corresponding bearing  238 A,  238 B and controls the position of pivot point  266  of the bearing  238 A,  238 B relative to its bearing retainer  244 A,  244 B. Screws  260  are manually installable and removable to aid in the installation and removal of charge roll  234  and cleaner roll  236  onto and off of cleaner bracket  222 . 
     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.