Abstract:
Developing cartridges for use in image forming apparatuses having an image carrier, include: (a) a case; (b) a developer carrier supported by the case (for holding developer thereon); and (c) a conductive member engaged with or provided on the case and being electrically connected to the developer carrier. The case may be configured to allow the developer carrier to be pressed against the image carrier at a designated pressing position in a pressing direction, and the conductive member may be configured to be supplied with power while being pressed by a power supply member in a direction parallel to the pressing direction. Alternatively, in some structures, the conductive member may be configured to be supplied with power while being pressed by a power supply member in a direction parallel to a line extending from the designated pressing position to a developer carrier and image carrier contacting position.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority from Japanese Patent Application No. 2005-277471, filed on Sep. 26, 2005, the entire subject matter of which is incorporated herein by reference.  
       FIELD  
       [0002]     Aspects of the invention relate to developing cartridges, process cartridges, and image forming apparatuses, e.g., using such developing cartridges and/or process cartridges.  
       BACKGROUND  
       [0003]     A photosensitive member cartridge, which is configured to set with a developing cartridge, is provided with an urging device for pressing a developing roller of the developing cartridge to a photosensitive member of the photosensitive member cartridge, via the developing cartridge, as disclosed in, for example, Japanese Laid-Open Patent Publication No. 2000-250310 or its counterpart U.S. Pat. No. 6,101,350. When the developing cartridge set with the photosensitive member cartridge is installed in an image forming apparatus, the developing cartridge is pressed by the urging device, so that the developing roller may be pressed against the photosensitive member, via the developing cartridge.  
         [0004]     Developing bias needs to be applied to the developing roller of the developing cartridge. As disclosed in, for example, Japanese Laid-Open Patent Publication No. 2005-258344 or its counterpart U.S. Patent Application Publication No. 2005/0201772, a conductive bearing member that rotatably supports a developing roller shaft, is provided in the developing cartridge. A power supply terminal provided in an image forming apparatus contacts a lower rear end of the bearing member.  
         [0005]     As disclosed in Japanese Laid-Open Patent Publication No. 2005-258344 or its counterpart U.S. Patent Application Publication No. 2005/0201772, when the power supply terminal provided in the image forming apparatus contacts the lower rear end of the conductive bearing member, the developing roller may be unstably pressed against the photosensitive drum, leading to deterioration of the formed image quality.  
       SUMMARY  
       [0006]     According to aspects of the invention, developing cartridges, process cartridges, and image forming apparatuses are provided in which a developing roller can be stably pressed against a photosensitive member, to form quality images, even when a conductive member configured to electrically connect to a developing roller shaft is pressed by a power feeding member for applying developing bias to the developing roller. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     Illustrative aspects of the invention will be described in detail with reference to the following figures wherein:  
         [0008]      FIG. 1  is a sectional side view of a printer, as an image forming apparatus, according an aspect of the invention;  
         [0009]      FIG. 2  is a plan view of a photosensitive member cartridge;  
         [0010]      FIG. 3  is a right side view of the photosensitive member cartridge;  
         [0011]      FIG. 4  is a plan view of a developing cartridge;  
         [0012]      FIGS. 5A and 5B  are left and right side views of the developing cartridge, respectively;  
         [0013]      FIG. 6  is a perspective view of an urging device and an action-receiving portion;  
         [0014]      FIG. 7  is a plan view of a process cartridge;  
         [0015]      FIG. 8  is a schematic illustrating the process cartridge inserted into a body housing;  
         [0016]      FIG. 9A  is a schematic illustrating the process cartridge being inserted into the body housing;  
         [0017]      FIG. 9B  is a schematic illustrating the process cartridge further being inserted into the body housing;  
         [0018]      FIG. 10A  is a schematic illustrating the process cartridge fully inserted into the image forming apparatus body housing and the lid closed; and  
         [0019]      FIG. 10B  is a schematic illustrating the lid open to enable removal of the process cartridge from the body housing. 
     
    
     DETAILED DESCRIPTION  
       [0020]     A laser beam printer, as an image forming apparatus, according to illustrative aspects of the invention will be described in detail with reference to the accompanying drawings. Of course, aspects of this invention may be practiced with other types of image forming apparatuses, such as copy machines, facsimile machines, other types of printers, and the like.  
         [0021]     As shown in  FIG. 1 , a process cartridge  2  having a photosensitive member cartridge  3  and a developing cartridge  4  is removably disposed in a substantially central portion of a body housing  1  of the printer. As shown in a left portion of  FIG. 1 , a fixer  5  is disposed adjacent to the process cartridge  2 . A sheet feeder  6  is disposed below the process cartridge  2  when the process cartridge  2  is installed in the body housing  1 . A sheet cassette  8  is insertable to a lower portion of the body housing  1  from a front face of the body housing  1  (the front face being indicated by arrow A).  
         [0022]     A laser scanning unit  7  is disposed below a discharge sheet tray  1   a  formed of synthetic resin. The discharge sheet tray  1   a  also serves as a cover.  
         [0023]     When print data is transmitted, based on a print instruction, to the printer from an external apparatus, for example, a personal computer, a sheet P (recording medium) is separated from a stack of sheets P on a support plate  9  of the sheet cassette  8  by a separator pad  11 , in a manner of one sheet at a time, as a pick-up roller  10  of the sheet feeder  6  rotates. The separated sheet P is then conveyed, via a pair of register rollers  12   a ,  12   b , to a position between a photosensitive drum  13 , as an electrostatic latent image carrier, of the process cartridge  2  and a transfer roller  14  pressed against a lower face of the photosensitive drum  13 .  
         [0024]     A laser beam is emitted from the laser scanning unit  7 , which includes a laser light-emitting portion, a polygon mirror  18 , a lens  19 , and a plurality of reflecting mirrors  20 . The laser beam travels to an upper peripheral surface portion of the photosensitive drum  13 , via a light entrance portion  31  formed in a case  30  of the photosensitive member cartridge  3 . The peripheral surface of the photosensitive drum  13  is thereby exposed to the laser beam in a manner corresponding to the print data, so as to form an electrostatic latent image.  
         [0025]     Toner, as developer, supplied from a developing roller  22  of the developing cartridge  4  becomes deposited on the electrostatic latent image on the photosensitive drum  13 , thereby making the image visible. After the visible toner image is transferred from the photosensitive drum  13  to the sheet P, the sheet P is conveyed between a heat roller  15  and a presser roller  16  in the fixer  5 , and the sheet P is subjected to a heat-fixing process. The sheet P is then discharged onto the discharge sheet tray  1   a , via a sheet discharge passage  17 .  
         [0026]     The process cartridge  2  includes the photosensitive member cartridge  3  having at least the photosensitive drum  13 , and the developing cartridge  4  having at least the developing roller  22  that is rotatably disposed in a case  21 . The developing cartridge  4  is detachably set in the photosensitive member cartridge  3 . The developing cartridge  4  may be installed in the body housing  1 , as the process cartridge  2 , together with the photosensitive member cartridge  3  or separately from the photosensitive member cartridge  3 .  
         [0027]     The structures of the photosensitive member cartridge  3  will be described in detail with reference to  FIGS. 2 and 3 . In the following description, the expressions “right” and “left” of the process cartridge  2 , the photosensitive member cartridge  3 , and the developing cartridge  4  are used to define a side thereof in conjunction with an orientation in which the cartridges  2 ,  3 ,  4  are installed in the body housing  1 .  
         [0028]     In the photosensitive member cartridge  3 , the photosensitive drum  13  is rotatably supported in a synthetic resin-made case  30 , near one side thereof. A lower portion of the transfer roller  14  disposed below the photosensitive drum  13  is covered with a bottom wall  30   a  of the case  30 .  
         [0029]     As shown in  FIG. 2 , an upper wall  30   b  of the case  30  of the photosensitive member cartridge  3  covers an upper portion of the photosensitive drum  13 . As shown in  FIGS. 1 and 2 , the light entrance portion  31 , allowing irradiation of an upper surface of the photosensitive drum  13  with the laser beam emitted from the laser scanning unit  7 , is formed in the upper wall  30   b . The light entrance portion  31  is elongated in the directions of an axis of the photosensitive drum  13 . Disposed adjacent to the light entrance portion  31  is, for example, a scorotron charger  36  that charges a photosensitive surface of the photosensitive drum  13  that is formed from an organic photosensitive material or the like.  
         [0030]     An electrostatic latent image is formed on the surface of the photosensitive drum  13  by scanning the laser beam over the surface of the drum  13  uniformly charged by the charger  36 . After the electrostatic latent image is made visible (developed) by deposition thereon of a thin layer of toner supplied via the developing roller  22 , the toner image is transferred to the sheet P at the transfer roller  14 .  
         [0031]     As shown in  FIG. 2 , a portion of the case  30  other than the upper wall  30   b  is open upward to define an accommodating portion  32  into which the developing cartridge  4  can be detachably set. An upper end face of each of right and left side walls  30   c  of the case  30  defines a guide groove  37  to guide a corresponding one of bearings  23   a ,  23   b  (see  FIG. 4 ). The guide grooves  37  slidably support the bearings  23   a ,  23   b , which are fitted on both end portions of the developing roller shaft  22   a  of the developing roller  22  so as to rotate relative to the shaft  22   a . The guide grooves  37  extend toward a shaft  13   a  of the photosensitive drum  13 . Therefore, when the developing cartridge  4  is set with respect to the photosensitive member cartridge  3 , the developing roller  22  can be positioned adjacent to the photosensitive drum  13  so as to face the drum  13 .  
         [0032]     An urging device  42  that presses the developing roller  22  against the photosensitive drum  13  via the developing cartridge  4  is pivotably and expandably mounted to an inner surface of each of the right and left side walls  30   c  of the photosensitive member cartridge  3 . As shown in  FIG. 6 , each urging device  42  has a pivot fulcrum member  39  provided with pivots  39   a ,  39   b  protruding integrally from the right and left sides thereof, a frame-like slide support member  40  that facilitates sliding movements of the pivot fulcrum member  39  therein, and an urging spring device  41 , such as a coil spring, that is disposed in the frame of the slide support member  40  so as to urge the pivot fulcrum member  39  toward one end. The slide support member  40  has a cylindrical motion acting portion  43  extending laterally. The motion acting portion  43  of each urging device  42  is disposed so that the portion  43  protrudes outward from a guide hole  44  (see  FIG. 3 ) formed in the corresponding one of the right and left side walls  30   c.    
         [0033]     When the developing cartridge  4  is installed in the body housing  1  as set relative to the photosensitive member cartridge  3 , an action-receiving portion  61  of the developing cartridge  4  is pressed by an end of the slide support members  40 , so that the developing roller  22  can be pressed against the photosensitive drum  13 , via the developing cartridge  4 , with the urging device  42  and the action-receiving portion  61 .  
         [0034]     As shown in  FIG. 3 , a lock device  46  that prevents the developing cartridge  4 , which is fitted into the accommodating portion  32 , from moving upward out of the accommodating portion  32 , is disposed at an inner side of one side wall  30   c  (the right side wall  30   c  in the illustrated example embodiment) of the photosensitive member cartridge  3 . A lock lever  47  provided in the lock device  46  is pressed down to unlock the developing cartridge  4  from the photosensitive member cartridge  3 .  
         [0035]     As shown in  FIG. 2 , rollers  50  are disposed at a plurality of positions (two positions in the illustrated example embodiment, that is, at right and left end portions) in the bottom wall  30   a  of the case  30 . The rollers  50  protrude upward from the inner surface of the bottom wall  30   a . When the developing cartridge  4  is inserted down into the accommodating portion  32 , the rollers  50  receive a portion of the weight of the developing cartridge  4 , at a side across the developing roller shaft  22   a  of the developing roller  22  from the photosensitive drum  13 . More specifically, the rollers  50  contact lower portions of a downward-convex curved surface of a toner containing chamber  24  (see  FIG. 1 ) formed in the case  21  of the developing cartridge  4 .  
         [0036]     The upper roller  12   a  of the pair of register rollers  12   a ,  12   b  is mounted to the bottom wall  30   a  of the case  30  of the photosensitive member cartridge  3  in such a manner that the upper roller  12   a  is prevented from detaching. The bottom wall  30   a  has a laterally elongated introduction hole  51  adjacent to the upper roller  12   a , to introduce the sheet P from the pair of register rollers  12   a ,  12   b  into a portion between the photosensitive drum  13  and the transfer roller  14 . The upper surface of a portion of the bottom wall  30   a  near the introduction hole  51  has many ribs  53  extending in a direction from the introduction hole  51  toward a portion between the photosensitive drum  13  and the transfer roller  14 . The ribs  53  are designed so that the sheet P can be smoothly conveyed with reduced contact resistance on the lower surface of the sheet P.  
         [0037]     Guiding members  56  (only one member  56  shown in  FIG. 3 ) protrude laterally from lower portions of the right and left sides of the photosensitive member cartridge  3 . When the photosensitive member cartridge  3  is inserted into the body housing  1 , the guiding members  56  fit into guide surfaces formed on inner surfaces of the right and left sides of the body housing  1 .  
         [0038]     The developing cartridge  4  will be described in detail below, with reference to  FIGS. 1, 4 ,  5 A, and  5 B.  
         [0039]     An agitator  27  that agitates toner in the toner containing chamber  24  is disposed in the case  21 . The toner agitated by the agitator  27  is discharged from the chamber  24  and is carried onto the outer peripheral surface of the developing roller  22 , which is rotatably disposed in the case  21 , via a supply roller  25 . The thickness of a toner layer on the developing roller  22  is regulated by a blade  26 , as shown in  FIG. 1 .  
         [0040]     As shown in  FIGS. 5A and 5B , the generally inverted triangular-shaped action-receiving portions  61  are integrally formed with the case  21  of the developing cartridge  4  so as to protrude from the right and left outer faces of the toner containing chamber  24 . When the photosensitive member cartridge  3  including the developing cartridge  4  mounted thereon is installed in the body housing  1 , the action-receiving portions  61  are urged by the urging devices  42  to press the developing roller  22  against the photosensitive drum  13 , via the developing cartridge  4 .  
         [0041]     As shown in  FIG. 4 , a holding portion  80  is formed on an upper and a lower face of the case  21  of the developing cartridge  4  (only holding portion  80  formed on the upper face is shown in  FIG. 4 ), to facilitate the handling of the developing cartridge  4 .  
         [0042]     The developing roller  22  is a rubber roller having a developing roller shaft  22   a  formed of metal, such as stainless steel, surrounded with a silicone rubber or urethane rubber dispersed with carbon black for conductivity. The surface of the developing roller  22  has a coating layer including fluorine. As shown in  FIG. 4 , the bearings  23   a ,  23   b  are rotatably fitted to the right and left end portions of the developing roller shaft  22   a , so as not to be removed from the end portions of the developing roller shaft  22   a . The bearings  23   a ,  23   b  are formed from a material having a low friction coefficient, such as an acetal resin or the like. The bearings  23   a ,  23   b  function as guided members when the developing cartridge  4  is set relative to the photosensitive member cartridge  3  along the guide grooves  37  formed on the right and left side walls  30   c.    
         [0043]     As shown in  FIGS. 4 and 5 B, a conductive member  66  configured to electrically connect to the developing roller shaft  22   a  is disposed on the developing cartridge  4 . It should be noted that the conductive member  66  is hatched in  FIGS. 4 and 5 B for clarity. The conductive member  66  is formed of conductive resin. The conductive member  66  is mounted on a side wall (right side wall) of the case  21  of the developing cartridge  4 . A projection  66   a  is integrally formed in the conductive member  66 .  
         [0044]     The operation of setting the developing cartridge  4  with respect to the photosensitive member cartridge  3  will be described. The developing cartridge  4  is inserted, with the developing roller  22  side being a leading side, into the upwardly open accommodating portion  32  provided in a front portion of the case  30  of the photosensitive member cartridge  3 . During the insertion of the developing roller  22  into the accommodating portion  32 , the bearings  23   a ,  23   b  disposed at the right and left side ends of the developing roller  22  slide down along the guide grooves  37  formed along the upper edges of the right and left side walls  30   c  of the case  30 , so as to approach the shaft  13   a  of the photosensitive drum  13 . The case  21  of the developing cartridge  4  is pivotable about the bearings  23   a ,  23   b  fitted on the developing roller shaft  2  when the bearings  23   a ,  23   b  are supported by the guide grooves  37 . Therefore, when the bearings  23   a ,  23   b  come to a position on the guide grooves  37  close to the shaft  13   a  of the photosensitive drum  13  (e.g., at “U”-shaped portions of the guide grooves  37 ), a toner containing chamber  24  side portion of the case  21  of the developing cartridge  4  comes into the accommodating portion  32  of the photosensitive member cartridge  3  by a pivoting motion about the developing roller shaft  22   a  of the developing roller  22 . Thus, the developing cartridge  4  is fittingly set in the accommodating portion  32 .  
         [0045]     While the developing cartridge  4  is set in the accommodating portion  32 , the rollers  50  slidingly contact a lower surface of the case  21  on the side of the toner containing chamber  24 , and the bearings  23   a ,  23   b  move along the guide grooves  37  to such a position that the developing roller  22  is located close to the photosensitive drum  13 . When insertion of the developing cartridge  4  into the photosensitive member cartridge  3  is complete, the developing cartridge  4  is prevented from moving out of the photosensitive member cartridge  3  by the lock device  46 .  
         [0046]     The bearings  23   a ,  23   b  are structured so as to rotate relative to the guide grooves  37 . Therefore, while the bearings  23   a ,  23   b  are moved along the guide grooves  37  during the insertion or removal of the developing cartridge  4  into or from the photosensitive member cartridge  3 , the bearings  23   a ,  23   b  can smoothly slide along the guide grooves  37 . The developing cartridge  4  and the photosensitive member cartridge  3  can be set into the process cartridge  2 , as shown in  FIG. 7 .  
         [0047]     The operation of installing the process cartridge  2  in the body housing  1  will be described below. The process cartridge  2  is designed so that the process cartridge  2  can be set into, and removed from, the body housing  1  when a lid  1   b  provided in the right-side end in  FIG. 1  (a front face) of the body housing  1  is downwardly turned to form a large opening. As shown in  FIG. 9A , when the process cartridge  2  is installed in the body housing  1 , the motion acting portion  43  of each urging device  42  contacts the rising slope surface of upper-side guide surfaces  55   a  provided on the inner surfaces of the right and left side portions of the body housing  1 , and each of the guiding members  56 , protruding laterally from lower portions of the right and left sides of the process cartridge  2  (photosensitive member cartridge  3 ), fits into a lower-side guide surface  55   b  (only one of the guiding members  56  is shown in the drawings). Thus, the process cartridge  2  is prevented from moving upward relative to the body housing  1 , and it is allowed only to be moved further inward toward the rear side of the printer along the lower-side guide surface  55   b.    
         [0048]     As the process cartridge  2  is pushed inward, the motion acting portion  43  is raised by the corresponding upper-side guide surface  55   a , so that the slide support member  40  of each urging device  42  pivots upward about the pivots  39   a ,  39   b . Therefore, the slide support member  40  of each urging device  42  restrains the corresponding one of the action-receiving portions  61  of the developing cartridge  4  in such a direction that a distal end portion of the slide support member  40  pushes the action-receiving portion  61 . When the motion acting portion  43  of each urging device  42  comes to a summit  55   d  of the upper-side guide surface  55   a , the slide support member  40  of each urging device  42  is pivoted to a most upward orientation. In this orientation, the distal end portion of the slide support member  40  of each urging device  42  keeps restraining the corresponding action-receiving portion  61 , as shown in  FIG. 9B .  
         [0049]     As the process cartridge  2  is pushed further inward, the shaft  13   a  of the photosensitive drum  13  is set to a predetermined position in an inward end portion  55   c  of each upper-side guide surface  55   a . At this position, an operator releases the process cartridge  2  from his/her hands, so that the developing cartridge  4  side portion of the process cartridge  2  is lowered by its own weight. This action places the upper register roller  12   a  (disposed at a lower surface side of the case  30  of the photosensitive member cartridge  3 ) on the lower register roller  12   b  (disposed in the body housing  1 ), and simultaneously, the guiding members  56  are supported at appropriate positions in the body housing  1 .  
         [0050]     When the process cartridge  2  is thus set in the body housing  1 , the distal end of the slide support member  40  of each urging device  42  presses the corresponding action-receiving portion  61 . Therefore, the developing roller  22  is pressed against the photosensitive drum  13  by the urging devices  42  and the action-receiving portions  61  via the developing cartridge  4 .  
         [0051]     In the above-description, the developing cartridge  4  is first set with respect to the photosensitive member cartridge  3 , and the overall process cartridge  2  is installed in the body housing  1 . However, the photosensitive member cartridge  3  and the developing cartridge  4  may be separately installed in the body housing  1 . In this case, the guide grooves  37  for slidably supporting the bearings  23   a ,  23   b  fitted on both ends of the developing roller shaft  22   a  may be formed on the right and left sides of the body housing  1 .  
         [0052]      FIG. 8  illustrates the process cartridge  2 , in which the developing cartridge  4  is set with respect to the photosensitive member cartridge  3 , installed in the body housing  1 . For clarity, unrelated portions are omitted in  FIG. 8 . As shown in  FIG. 8 , the projection  66   a  of the conductive member  66  (which is configured to electrically connect to the developing roller shaft  22   a ) is pressed by a power supply member  70  for applying developing bias to the developing roller  22 .  
         [0053]     Reference numeral  71   a  represents a developing cartridge push position at which the developing cartridge  4  is pushed as the distal end portion of the slide support member  40  of the urging device  42  pushes the action-receiving portion  61 .  
         [0054]     Line X represents a developing cartridge pushing direction to which the developing cartridge  4  is pushed by the urging device  42 . More specifically, the pushing direction X is directed toward the developing cartridge push position  71   a  from the pivot  39   b.    
         [0055]     Reference numeral  72   a  represents a developing position where the developing roller  22  contacts the photosensitive drum  13 . The developing position  72   a  is located on a line (not shown) connecting axes of the developing roller  22  and the shaft  13   a  of the photosensitive drum  13 .  
         [0056]     The projection  66   a  of the conductive member  66 , which is configured to electrically connect between the developing roller shaft  22   a  and the power supply member  70  for applying developing bias to the developing roller  22 , is disposed so as to be pushed by the power supply member  70  in a direction parallel to the developing cartridge pushing direction X when the developing cartridge  4  is set in the body housing  1 . Therefore, the developing cartridge  4  may be stably held in the photosensitive member cartridge  3  while rattling of the developing cartridge  4  is reduced or minimized. Thus, the photosensitive drum  13  and the developing roller  22  may be prevented from unstably contacting each other and consequently, fine image quality may be maintained.  
         [0057]     The projection  66   a  is pushed by the power supply member  70  in a direction parallel to a direction Y extending from the developing cartridge push position  71   a  to the developing position  72   a . Thus, fine image quality may be reliably maintained while the photosensitive drum  13  and the developing roller  22  are prevented from unstably contacting each other.  
         [0058]     The projection  66   a  is disposed so as to be pushed by the power supply member  70  on a line connecting the developing cartridge push position  71   a  to the developing position  72   a . Therefore, the contact between the photosensitive drum  13  and the developing roller  22  may be stabilized while rattling of the developing cartridge  4  is reliably reduced or minimized. Thus, fine image quality may be reliably maintained.  
         [0059]     The guide grooves  37  are formed on the upper edges of the right and left side walls  30   c  of the case  30  for guiding the developing roller shaft  22   a  when the developing cartridge  4  is set with respect to the photosensitive member cartridge  3 . When the developing cartridge  4  installed in the body housing  1  is pressed by the urging device  42 , the developing roller shaft  22   a  slides along rearmost parts  37   a  (in  FIG. 3 ) of the guide grooves  37 , and the developing roller  22  is made to contact with and press against the photosensitive drum  13 . The projection  66   a  of the conductive member  66  is pressed by the power supply member  70  in a direction parallel to a rearmost part guiding direction Z in which the rearmost part  37   a  of the guide grooves  37  guides the developing roller shaft  22   a . Therefore, influences of the pressing of the projection  66  by the power supply member  70  over the contact of the developing roller  22  to the photosensitive drum  13  at the developing position  72   a  may be reliably reduced. Thus, the contact between the developing roller  22  and the photosensitive drum  13  at the developing position  72   a  may be reliably stabilized while rattling of the developing cartridge  4  is reduced or minimized. Accordingly, high image quality may be maintained.  
         [0060]     The power supply member  70  is connected to the lid  1   b . As shown in  FIG. 10A , when the lid  1   b  is closed after the process cartridge  2  is installed in the body housing  1 , the power supply member  70  contacts the projection  66   a  from a side opposite to the developing roller  22  and presses the projection  66   a . As shown in  FIG. 10B , when the lid  1   b  is open to remove/install the process cartridge  2  from/in the body housing  1 , the power supply member  70  is moved to a position outside a process cartridge removal/installation area or a process cartridge removal/installation path, such that the power supply member  70  does not get in the way when the process cartridge  2  is removed from or installed in the body housing  1 . Therefore, damage to the power supply member  70  and/or the projection  66   a  by colliding with each other during the installation or removal of the process cartridge  2  from the body housing  1  may be prevented. Thus, the electrical connection between the power supply member  70  and the projection  66   a  may be stably made.  
         [0061]     In this example embodiment, the power supply member  70  is formed by bending a conductive wire to have a flat portion that presses the projection  66   a . However, the power supply member  70  may be formed in any shape and/or in any desired manner as long as the power supply member  70  can stably press against and/or otherwise make reliable electrical connection with the projection  66   a.    
         [0062]     As shown in  FIG. 8 , it is preferable that the projection  66   a  of the conductive member  66  be pressed by the power supply member  70  on the line connecting the developing cartridge push position  71   a  and the developing position  72   a . However, as shown by a projection  66   a ′ and a power supply member  70 ′ in  FIG. 8 , the projection  66   a  ( 66   a ′) may be pressed by the power supply member  70  ( 70 ′) at a position out of the line connecting the developing cartridge push position  71   a  and the developing position  72   a  if the projection  66   a  ( 66   a ′) is pressed by the power supply member  70  ( 70 ′) in a direction parallel to the developing cartridge pushing direction X by the urging device  42  and parallel to the direction Y extending from the developing cartridge push position  71   a  to the developing position  72   a . In addition, the projection  66   a  may be pressed in a direction parallel to the developing cartridge pushing direction X or the direction Y extending from the developing cartridge push position  71   a  to the developing position  72   a . In this case also, it is unlikely that rattling of the developing cartridge  4  will be caused by pressing the conductive member  66  by the power supply member  70 . Thus, the contact between the developing roller  22  and the photosensitive drum  13  at the developing position  72   a  may be reliably stabilized, thereby maintaining high image quality.  
         [0063]     In this example embodiment, the urging device  42 , as a developing cartridge pushing member, is provided in the photosensitive member cartridge  3 . While the motion acting portion  43  of each urging device  42  is guided by the guide surface formed on the inner surface of the right and left side portions of the body housing  1  during insertion of the photosensitive member cartridge  3  into the body housing  1 , the distal end portion of the slide support member  40  pushes the action-receiving portion  61  of the developing cartridge  4 . Thus, the developing roller  22  is pressed against the photosensitive drum  13 , via the developing cartridge  4 . However, structures for pressing the developing cartridge  4  are not limited to the above-described structures. For example, the developing cartridge  4  may be directly pressed by a developing cartridge pressing member disposed in the body housing  1  to press the developing roller  22  against the photosensitive drum  13 .  
         [0064]     Further, the power supply member  70  for applying the developing bias to the developing roller  22  may be provided in the body housing  1 , like in this example embodiment, or a relay electrode configured to contact a power feeding member disposed in the body housing  1  may be provided in the photosensitive member cartridge  3 . In this case, the relay electrode may correspond to the power supply member.  
         [0065]     While the invention has been described in connection with various example structures and illustrative aspects, it will be understood by those skilled in the art that other variations and modifications of the structures and aspects described above may be made without departing from the scope of the invention. Other structures and aspects will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples only are illustrative with the true scope of the invention being defined by the following claims.