Abstract:
According to an aspect of the present invention, there is provided a cartridge detachably mountable to a main assembly of an image forming apparatus, comprising an electric energy receiving member; a frame of resin material; an electrode member which is molded by injecting electroconductive resin material into the frame which provides an electroconductive path between the electric energy receiving member and a main assembly electrical contact provided in the main assembly when the cartridge is mounted to the main assembly, the electrode member having a projected portion projected from a surface of the frame for contacting the main assembly electrical contact, the projected portion being provided by changing a direction of flow of the injected electroconductive resin material by the metal mold or the frame.

Description:
FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to a cartridge removably installable in the main assembly of an electrophotographic image forming apparatus. 
     A cartridge system has been in use for quite sometime. It integrally places a photosensitive drum and one or more means for processing the photosensitive drum, in a cartridge which is removably installable in the main assembly of an electrophotographic image forming apparatus. Thus, as a cartridge is properly situated in the main assembly of an image forming apparatus, the electrodes of the main assembly of the image forming apparatus are in contact with the electrical contacts of the cartridge to provide electrical connection between the photosensitive drum(s), processing means, etc., which need to be supplied with electric power from the main assembly, remain electrically in contact with the main assembly, making it possible to charge the photosensitive drum(s) and developer bearing member(s), keep the photosensitive drum(s) grounded, electrostatically measure the residual amount of toner in the main assembly, and the like processes. 
     One of the patent applications in which such system as the one described above is disclosed is Japanese Laid-open Patent Application 2007-47491. 
     As a method for providing a cartridge with electrical contacts (electrodes), it is possible to form the electrical contacts as integral parts of the processing means supporting portion (frame) of the cartridge, by injecting electrically conductive resin (resin which contains electrically conductive substance) in the space between the processing means supporting portion (frame) and an electrical contact formation mold placed in contact with the processing means supporting portion (frame). It is also possible to form the electrical contacts as integral parts of the processing means supporting portion (frame) of a process cartridge, with the use of such a two color injection molding that injects the resin of the first color, or the material for the processing means supporting portion (frame), into the mold for the supporting portion (frame), and then, injecting the resin of the second color, or the material for the electrical contacts. 
     In a case where the electrical contacts are formed of electrically conductive resin, the resin is desired to be as small as possible in electrical resistance. 
     SUMMARY OF THE INVENTION 
     The present invention was made in consideration of the above-described issues. Thus, the primary object of the present invention is to provide a cartridge, the electrical contacts of which are made of electrically conductive resin, and are significantly smaller in electrical resistance than any electrical contact made for a cartridge, which is in accordance with the prior art. 
     According to an aspect of the present invention, there is provided a cartridge detachably mountable to a main assembly of an image forming apparatus, comprising an electric energy receiving member; a frame of resin material; an electrode member which is molded by injecting electroconductive resin material into said frame which provides an electroconductive path between said electric energy receiving member and a main assembly electrical contact provided in the main assembly when said cartridge is mounted to the main assembly, said electrode member having a projected portion projected from a surface of said frame for contacting said main assembly electrical contact, said projected portion being provided by changing a direction of flow of the injected electroconductive resin material by said metal mold or said frame. 
     These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1(   a )- 1 ( c ) are sectional views of the combination of the drum supporting frame, electrical contact formation mold, and electrically conductive resin (electrical contact) in the first embodiment of the present invention, and shows the sequential steps for forming the electrical contact in such a manner that the electrical contact envelops the rib with which the drum supporting frame is provided. 
         FIGS. 2(   a ) and  2 ( b ) are schematic sectional views of the image forming apparatus and process cartridge, respectively, in the first embodiment of the present invention, at a plane parallel to the recording medium conveyance direction of the apparatus. 
         FIG. 3  is a perspective view of the combination of the drum and drum supporting frame (sub-frame) of the process cartridge in the first embodiment, and shows the general structure of the combination. 
         FIGS. 4(   a )- 4 ( c ) are side views of the electrical contact and its adjacencies of the combination of the drum and drum supporting frame (sub-frame) of the process cartridge in the first embodiment, 
         FIGS. 5(   a )- 5 ( e ) are schematic drawings of the drum supporting frame (sub-frame) of the process cartridge in the first embodiment, prior to the injection of the electrically conductive resin. 
         FIG. 6  is a schematic perspective view of the mold to be placed in contact with the drum supporting frame (sub-frame) of the process cartridge, to form the electrical contact, in the first embodiment, as seen from the inward side of the mold. 
         FIG. 7  is a schematic perspective view of the mold to be placed in contact with the drum supporting frame (sub-frame) of the process cartridge, to form the electrical contact, in the first embodiment, as seen from the outward side of the mold. 
         FIGS. 8(   a )- 8 ( d ) are drawings for showing the sequential steps through which the molds for the formation of the electrical contact are attached to the drum supporting frame (sub-frame) of the process cartridge in the first embodiment. 
         FIGS. 9(   a )- 9 ( d ) are drawings for showing the sequential steps through which the molds for the formation of the electrical contact are separated from the drum supporting frame (sub-frame) of the process cartridge in the first embodiment. 
         FIG. 10  is a drawing for describing the electrical contact for the charge roller in the first embodiment. 
         FIG. 11  is a drawing for describing the area of contact of the electrical contact of the process cartridge, in the first embodiment, by which the main assembly electrode is contacted. 
         FIGS. 12(   a )- 12 ( b ) are perspective views of the electrical contact of the process cartridge in the first embodiment, after the separation of the molds from the contact; and  FIGS. 12(   c )- 12 ( f ) are sectional view of various portions of the contact. 
         FIG. 12  is for describing the functions of various portion of the electrical contact. 
         FIGS. 13(   a ) and  13 ( b ) are perspective views of the combination of the electrode of the main assembly of the image forming apparatus and the compression spring and charge roller terminal of the process cartridge, in the first embodiment. They correspond to  FIGS. 12(   a ) and  12 ( b ). 
         FIG. 14  is a drawing for describing the sequential steps through which the electrically conductive resin is injected into the space formed between the drum supporting frame (sub-frame) of the process cartridge, and the electrical contact formation mold, in the first embodiment. 
         FIG. 15  is a drawing for describing the resin pressure in the first embodiment. 
         FIG. 16  is a drawing for describing the electrical contact formed of electrically conductive resin, as an integral part of the developing means supporting frame (sub-frame) of the process cartridge. 
         FIGS. 17(   a ) and  17 ( b ) are perspective views of the combination of the electrode of the main assembly of the image forming apparatus, and the compression spring and charge roller terminal of the process cartridge, in the second embodiment. 
         FIG. 18  is a drawing for describing the electrical contact formation mold in the second embodiment. 
         FIG. 19  is a perspective view of the lengthwise end of the drum supporting frame (sub-frame) of the process cartridge in the second embodiment, which has the electrical contacts, after the injection of the electrically conductive resin into the electrical contact formation space in the frame. 
         FIG. 20  is a drawing for describing the attachment of the electrical contact formation molds and drum supporting frame (sub-frame) backing member, to the drum supporting frame (sub-frame) of the cartridge in the second embodiment, and their separation of from the drum supporting frame, in the second embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, the embodiments of the present invention are described in detail with reference to the appended drawings. However, the measurement, material, and shape of the structural components of the process cartridges in the following embodiments of the present invention, and the positional relationship among the structural components, etc., are not intended to limit the present invention in scope. That is, the present invention is also applicable to cartridges different in structure and/or various settings from those in the following embodiments. 
     The present invention relates to a cartridge removably installable in the image assembly of an electrophotographic image forming apparatus. Here, an “electrophotographic image forming apparatus” is an apparatus for forming an image on recording medium with the use of an electrophotographic image forming process. Some of the examples of an electrophotographic image forming apparatus are an electrophotographic copying machine, an electrophotographic printer (laser beam printer, LED printer, etc.), a facsimile apparatus, and a word processor. A “cartridge” is a general term for a process cartridge made up of a drum supporting frame for supporting an electrophotographic photosensitive drum (electrophotographic photosensitive member), a development roller supporting frame for supporting a developing means, an electrophotographic photosensitive drum, drum processing means, and a shell (cartridge) in which the preceding components are integrally placed. The processing means are means for processing the electrophotographic photosensitive drum. Some of the examples of the processing means are the charging means, developing means, and cleaning means which act on the electrophotographic drum, and also, a toner supply roller for coating the peripheral surface of the developer bearing member (development roller) with toner, a means for detecting the amount of toner remaining in a cartridge, and the like. 
     [Embodiment 1] 
     First, the electrophotographic image forming apparatus (which will be referred to simply as image forming apparatus, hereafter) in this embodiment is described about its structural components, in particular, the structure of the electrical contacts (which hereafter may be referred to simply as contacts) of the drum supporting frame of the cartridge, and the method for forming the electrical contacts. 
     (1) Image Forming Apparatus 
     To begin with, referring to  FIG. 2 , the image forming apparatus A in this embodiment is described.  FIG. 2(   a ) is a schematic sectional view of the image forming apparatus A (laser beam printer), which includes a process cartridge B. It shows the general structure of the apparatus A. 
     The formation of an image on a sheet  2  of recording medium by the image forming apparatus A shown in  FIG. 2(   a ) is as follows: First, the beam of laser light is projected upon the electrophotographic photosensitive drum  7  (which hereafter will be referred to simply as photosensitive drum) from an optical system  1  while being modulated with the information about the image to be formed, whereby an electrostatic latent image is formed on the photosensitive drum  7 . This latent image is developed by developer (which will be referred to as toner), into a visible image, that is, an image formed of toner. Meanwhile the sheet  2  of recording medium is pulled out of a sheet feeder cassette  3 , and is conveyed to where a transfer roller  4  is located, in synchronism with the progression of the formation of the toner image on the photosensitive drum  7 . Then, the toner image formed on the photosensitive drum  7  is transferred onto the sheet  2  of recording medium. Thereafter, the toner image on the sheet  2  is fixed to the sheet  2  by the heat and pressure applied thereto by a fixing means  5 . Finally, the sheet  2  is discharged into a delivery tray  6 . 
     (2) Process Cartridge 
     Next, referring to  FIGS. 2(   a ) and  2 ( b ), the process cartridge B is described.  FIG. 2(   b ) is a sectional view of the process cartridge B in this embodiment. It shows the general structure of the process cartridge B. 
     The process cartridge B is a combination of a development section C and a latent image forming section D. The two sections C and D are connected to each other so that they are allowed to pivotally move relative to each other. The process cartridge B is removably installable in the main assembly  100  of the image forming apparatus A. The development section C has a developing means and a development roller supporting frame  8 . The developing means is made up of a development roller  12 , a toner supply roller  16 , etc. The development roller supporting frame  8  supports the abovementioned developing means, and also, stores toner. The latent image forming section D is made up of such structural components as the photosensitive drum  7  and a cleaning blade  14 , etc., and a drum supporting frame  13  for supporting these structural components. 
     The toner stored in the toner storage  9  of the development section C is conveyed to a development chamber  10 , in which the development roller  12 , toner supply roller  16 , and development blade are present, which are arranged in such a manner that the peripheral surface of the toner supply roller  16  and the toner layer regulating edge of the development blade  11  are in contact with the peripheral surface of the development roller  12 . Thus, as the toner supply roller  16  is rotated in the direction indicated by an arrow mark E in  FIG. 2(   b ), a layer of toner is formed on the peripheral surface of the development roller  12 . As the toner particles in the toner layer on the peripheral surface of the development roller  12  are transferred onto the peripheral surface of the photosensitive drum  7 , in the pattern of the latent image on the peripheral surface of the photosensitive drum  7 , an image is formed of the toner particles, on the peripheral surface of the photosensitive drum  7 . 
     After the transfer of the toner image on the photosensitive drum  7  onto the sheet  2  of recording medium by the transfer roller  4 , the toner remaining on the peripheral surface of the photosensitive drum  7  is scraped down by the cleaning blade  14 , to be stored in (removed into) a waste toner storage chamber. Thereafter, the peripheral surface of the photosensitive drum  7  is uniformly charged by the charge roller, as charging means (processing means), being readied for the latent image formation by the optical system  1 . 
     (3) Latent Image Forming Section 
     Next, referring to  FIGS. 2(   b ),  3  and  4 , the latent image forming section of the process cartridge B is described about its general structure.  FIG. 3  is a perspective view of the latent image forming section D, in particular, the portions involved in the charging process, of the process cartridge B, when the process cartridge B is in the main assembly  100  of the image forming apparatus A.  FIG. 4(   a ) is a side view (as seen from downstream side of arrow mark N in  FIG. 3)  of the lengthwise end portion of the section D of the process cartridge B, which has the electrical contact for the photosensitive drum  7 .  FIG. 4(   b ) is a sectional view of the portion of the latent image forming section D in  FIG. 4(   a ), at a plane which coincides with a line Y-Y in  FIG. 4(   a ). It shows the electrical contact and its adjacencies. 
     Referring to  FIGS. 3 and 4 , the charge roller  18  for charging the peripheral surface of the photosensitive drum  7  is rotatably supported by the lengthwise end portions of its axle, by a pair of charge roller terminals  23   b  and  23   a  made of an electrically conductive substance (electrically conductive resin, for example). In  FIGS. 3 and 4 , the lengthwise end portions of the axle of the charge roller  18  are designated by referential codes  18   a  and  18   b , one for one. Hereafter, they will be referred to as the metallic core end portions  18   a  and  18   b  of the charge roller  18 . The charge roller terminals  23   a  and  23   b  are provided with a pair of electrically conductive compression springs  22   a  and  23   b , one for one. Further, the charge roller terminals  23   a  and  23   b  are attached to the drum supporting frame  13  in such a manner that the compression springs  22   a  and  22   b  remain compressible. That is, the charge roller  18  is indirectly supported by the drum supporting frame  13 . Next, referring to  FIG. 4(   b ), as the photosensitive drum  7  and charge roller  18  are pressed upon each other, the compression springs  22   a  and  22   b  are compressed, and therefore, the charge roller  18  is kept pressed upon the photosensitive drum  7  by a preset amount of pressure generated by the resiliency of the compression springs  22   a  and  22   b.    
     (4) Structure of Electrical Contact of Latent Image Forming Section of Process Cartridge, and Method for Applying Voltage to Charge Roller 
     Next, referring to  FIGS. 3 ,  4  and  13 , the method for charging the photosensitive drum  7  is described. Referring to  FIGS. 3 and 4 , an electrical contact  19  is an integral part of the drum supporting frame  13 . The method for forming the electrical contact  19  will be concretely described in Section 8 of this document. Roughly speaking, the electrical contact  19  is formed by injecting electrically conductive resin  34  (resin which contains electrically conductive substance) into a space (gap) which is formed between the drum supporting frame  13  and a pair of molds  27  and  28 , as the molds  27  and  28  are attached to the drum supporting frame  13  ( FIG. 14 ). 
     As described above, the electrical contact  19 , which is the electrical contact of the latent image forming section of the process cartridge B, is molded of electrically conductive resin, by the injection of the electrically conductive resin into the space between the drum supporting frame  13 , and the pair of molds  27  and  28  attached to the frame  13 . As the process cartridge B is installed into the main assembly  100  of the image forming apparatus A, the electrical contact  19  becomes an electricity passage which connects between the electrode (electrical contact)  21  of the main assembly  100  and the charge roller  18 . Here, it is the charge roller  18  that is electrically connected to the electrode  21  with which the main assembly  100  of the image forming apparatus A is provided.  FIG. 13  is a drawing of the electrical contact  19 , electrode  21  (as electrical contact of main assembly  100 ), compression spring  22   a , and charge roller electrode  23   a , which will be described in Section (9). The electrical contact  19  has the first and second points of contact (which will be referred to as charge roller contact point  19   b  and contacting surface  19   a  (main assembly contacting point), respectively). 
     As will be described later in Section (9), the electrical contact  19  has a protrusion  19   g , the contacting surface  19   a  (as electrical contact of cartridge), a charge roller contact point  19   b , a runner section  19   c , and a gate  19   d . The charge roller contact point  19   b  branches from the runner section  19   c . The contacting surface  19   a  and charge roller contact point  19   b  are in connection to each other through the runner section  19   c . They are integral parts of the electrical contact  19 . The projection  19   g  is on the outward surface of the downstream side wall of the drum supporting frame  13  (end wall in terms of direction parallel to axle of photosensitive drum  7 ) (with reference to direction of arrow mark N in  FIG. 3 ). The contacting surface  19   a  is at the end of the projection  19   g.    
     As the process cartridge B is installed into the main assembly  100  of the image forming apparatus A, the electrode  21  of the main assembly  100  comes into contact with the contacting surface  19   a  of the electrical contact  19  which is an integral part of the drum supporting frame  13 . As for the point  19   b  of contact for the charge roller  18 , which serves as the seat for the compression spring  22   a  (which is electrically conductive), it is in contact with the compression spring  22   a , providing electrical connection between the compression spring  22   a  and electrical contact  19 . 
     After the installation of the process cartridge B into the main assembly  100  of the image forming apparatus A, voltage is applied to the electrode  21  of the main assembly  100  in response to a command from the controller section (unshown) of the main assembly  100 . Thus, voltage is applied to the peripheral surface of the charge roller  18  (as drum charging member) by way of the contacting surface  19   a , runner section  19   c , charge roller contact point  19   b , compression spring  22   a , charge roller terminal  23   a  (formed of electrically conductive resin), and metallic core  18   a  of the charge roller  18 . Consequently, the peripheral surface of the photosensitive drum  7  is uniformly charged by the charge roller  18 . That is, the electrical contact  19  is for establishing electrical connection between the charge roller  18  and main assembly electrode  21 . 
     In this embodiment, the main assembly electrode  21  is directly connected to the electrical contact  19 . However, they may be indirectly connected to each other, with the placement of an electrically conductive member between the two. Further, the electrical contact  19  and charge roller  18  are electrically in contact with each other through the charge roller terminal  23   a  and compression spring  22   a . However, the process cartridge B may be structured so that the electrical contact  19  is directly in contact with the charge roller  18 . 
     Further, in this embodiment, the electrical contact  19  is for charging the photosensitive drum  7 . However, this embodiment is not intended to limit the present invention in terms of the usage of the electrical contact  19 . That is, the present invention is also applicable to any electrical contact for a process cartridge. For example, it is applicable to an electrical contact for supplying the development roller (as developing means) and toner supply roller  16  with electrical power, an electrical contact for connecting the process cartridge B with the drum ground (unshown), an electrical contact for supplying the circuit (unshown) for detecting the amount of the residual toner in the process cartridge B, and the like. 
     (5) Drum Supporting Frame 
     Next, referring to  FIGS. 4 and 5 , the shape of the drum supporting frame  13  is described.  FIG. 5  shows the shape of the drum supporting frame  13  before the injection of the electrically conductive resin  34 . More specifically,  FIG. 5(   a ) is a side view of the lengthwise end of the drum supporting frame  13 , which is going to have the electrical contact  19  (as seen from the downstream side, in terms of direction indicated by arrow mark N in  FIG. 3 .  FIG. 5(   b ) is an external view of the lengthwise end portion of the drum supporting frame  13 , shown in  FIG. 5(   a ), as seen from its side having the resin injection opening (gate)  13   d  of the drum supporting frame  13  (right side view as seen from same direction as direction from which drum supporting frame  13  is seen in  FIG. 15(   a )).  FIG. 5(   c ) is a sectional view of the drum supporting frame  13  at a plane which coincides with a line Z-Z in  FIG. 5(   b ).  FIG. 5(   d ) is a sectional view of the drum supporting frame  13  at a plane which coincides with a line V-V in  FIG. 5(   a ).  FIG. 5(   e ) is a sectional view of the drum supporting frame  13  at a plane which coincides with a line W-W in  FIG. 5(   a ). 
     Referring to  FIGS. 5(   a ) and  5 ( c ), the drum supporting frame  13  has: a surface  13   a  for forming the contacting surface  19   a ; a surface  13   b  for forming the charge roller contact point  19   b , which functions as the seat for the compression spring  22   a ; and a mold insertion hole  13   g.    
     Further, it has: surfaces  13   e  and  13   f , with which the molds  27  and  28  are placed in contact when the contacting surface  19   a  and charge roller contact point  19   b  are molded. Further, it has: a resin injection hole  13   d , through which the electrically conductive resin  34  is injected; and a rib  13   k , which projects into the electrical contact formation space from the surface  13   a  for forming the contacting surface  19   a  of the electrical contact  19 , on the downstream side in terms of the resin flow. Further, it has a runner  13   c  (through which electrically conductive resin  34  is guided into its destinations), which is in the form of a tunnel. The runner  13   c  (tunnel) branches at a point  13   h , into a passage (runner) which leads to the surface area  13   a  for forming the contacting surface  19   a  of the electrical contact  19 , and the surface area  13   b  for forming the charge roller contact point  19   b.    
     (6) Mold for Forming Contacting Surface of Electrical Contact 
     Next, referring to  FIGS. 5 ,  6 ,  10  and  11 , the mold for forming the contacting surface  19   a  of the electrical contact  19  is described.  FIG. 6  is a drawing of one (mold  27 ) of the two molds which are placed in contact with the drum supporting frame  13  to form the electrical contact  19 .  FIG. 10  is a schematic drawing for describing the sequential steps through which the charge roller contact point  19   b  is formed by the injection of the electrically conductive resin  34  into the space formed by placing the mold  27  in contact with the drum supporting frame  13 . More specifically,  FIG. 10(   a ) is a schematic perspective view of the combination of the drum supporting frame  13  (partially broken), mold  27 , and mold  28  after the formation of a spring seat formation space  20   b , by the placement of the mold  27  in contact with the drum supporting frame  13 .  FIG. 10(   b ) is a schematic perspective view of the combination of the drum supporting frame  13  (partially broken), mold  27 , and mold  28  after the electrically conductive resin  34  has begun to flow into the spring seat formation space  20   b  through the tunnel-like runner  13   c .  FIG. 10(   c ) is a schematic perspective view of the combination of the drum supporting frame  13  (partially broken), mold  27 , and mold  28  after the completion of the injection of the spring seat formation space  20   b , that is, after the completion of the formation of the charge roller contact point  19   b.    
       FIG. 11  is a schematic drawing for describing the contacting surface  19   a , which is formed as the electrically conductive resin  34  is injected into the electrical contact formation space created between the drum supporting frame  13  and mold  27  as the mold  27  is joined with the drum supporting frame  13 . As the electrically conductive resin  34  is injected into the electrical contact formation space, the electrical contact  19  is formed, with the rib  13   k  remaining inserted into the electrical contact formation space  27   c  (which will be referred to simply as recess  27   c ).  FIG. 11(   a ) is a schematic perspective view of the combination of the drum supporting frame  13  (partially broken), mold  27 , and mold  28  after the attachment of the mold  27  to the drum supporting frame  13  in such a manner that the electrical contact formation space  13   a  of the drum supporting frame  13  becomes connected to the recess  27   c  of the mold  27  to create the electrical contact formation space  20   a .  FIG. 11(   b ) is a schematic perspective view of the combination of the drum supporting frame  13  (partially broken), mold  27 , and mold  28  after the electrically conductive resin  34  has begun to flow into contacting surface formation space  20   a  through the tunnel-shaped runner  13   c .  FIG. 11(   c ) is a schematic perspective view of the combination of the drum supporting frame  13  (partially broken), mold  27 , and mold  28  after the envelopment of the rib  13   k  by the electrically conductive resin  34 , and completion of the contacting surface  19   a.    
     Referring to  FIG. 6 , the mold  27 , which is for forming the electrical contact  19 , has a surface  27   a , a recess  27   c , and a projection  27   b  (mold projection). The surface  27   a  meets the mold facing surface  13   e  of the drum supporting frame  13 . The recess  27   c  is such a portion of the mold  27  that becomes a part of the electrical contact formation space  20   a , in particular, the contacting surface  19   a . The projection  27   b  is for forming the charge roller contact point  19   b , which functions as the seat for the compression spring  22   a  inserted into the mold insertion hole  13   g.    
     (7) Resin Injection Gate Mold 
     Next, referring to  FIGS. 4 ,  7  and  14 , the mold  28 , which is the other of the two molds described in Section (6) is described. The mold  28  is the mold, through which the electrically conductive resin  34  is injected into the electrical contact formation space  20   a  to form the electrical contact  19 .  FIGS. 14(   a ),  14 ( b ) and  14 ( c ) are schematic perspective/sectional views of the combination of the drum supporting frame  13  (partially broken), mold  28 , and gate  30 , at a vertical plane which coincides with the axial line of the gate  30 . They sequentially describe the process of forming the electrical contact  19 , from when the mold  28  was joined with the drum supporting frame  13  to when the injection of the electrically conductive resin  34  into the electrical contact formation space  20   a  is completed.  FIG. 7  is a drawing of the other (mold  28 ) of the two molds, described in Section (6), which are placed in contact with the drum supporting frame  13  to form the electrical contact  19 . The mold  28  has: a surface  28   a , which is to be placed in contact with the surface  13   f  of the drum supporting frame  13 ; and a hole  28   b  into which the gate  30  for injecting the electrically conductive resin  34  is to be fitted. 
     (8) Method for Forming Electrical Contact 
     Next, referring to  FIGS. 4 ,  5 ,  6 ,  8 ,  9 ,  10 ,  11  and  14 , the method for forming the contacting surface  19   a  and charge roller contact point  19   b  is described.  FIGS. 8(   a )-( d ) are perspective view of the combination of the drum supporting frame  13 , and molds  27  and  28 , which show the sequential steps through which the molds  27  and  28  are attached to the drum supporting frame  13 .  FIGS. 9(   a )- 9 ( d ) are perspective views of the combination of the drum supporting frame  13  and the molds  27  and  28 , which show the sequential steps through which the molds  27  and  28  are separated from the drum supporting frame  13 . The electrical contact  19  is molded of the electrically conductive resin  34 , as an integral part of the drum supporting frame  13 , by the injection of the electrically conductive resin  34  into the space formed between the drum supporting frame  13  and mold  27 . 
     To begin with, referring to  FIG. 8(   a ), the mold  28  is attached to the drum supporting frame  13  (from direction indicated by arrow mark in  FIG. 8(   a )). During this process, the surface  28   a  of the mold  28  meets the surface of the drum supporting frame  13 , which has the resin inlet  13   d . Next, referring to  FIG. 8(   b ), the mold  27  is attached to the drum supporting frame  13  (from direction indicated by arrow mark in  FIG. 8(   b )). During this process, the surface  27   a  of the mold  27  meets the surface  13   e  of the drum supporting frame  13 , in such a manner that the rib  13   k  enters the recess  27   c  of the mold  27 . Further, a drum supporting frame backing member  37  (which will be referred to simply as backing member, hereafter) is made to meet the opposite side of the drum supporting frame  13  from the resin inlet  13   d  and surface  13   e  of the drum supporting frame  13 , to prevent the deformation of the drum supporting frame  13  and the like problem. The backing member  37  plays also a role of preventing the problem that when the electrically conductive resin  34  is injected, the drum supporting frame  13  is moved by the pressure applied to the drum supporting frame  13  by the electrically conductive resin  34 , in the direction in which the electrically conductive resin  34  is injected (backing of drum supporting frame  13  will be described in detail in Section 10)). 
       FIG. 8(   c ) shows the combination of the drum supporting frame  13 , mold  27 , and mold  28  after the attachment of the molds  27  and  28  to the drum supporting frame  13 . Referring to  FIGS. 5(   a ),  5 ( d ) and  10 ( a ), when the mold  27  is attached to the drum supporting frame  13 , the projection  27   b  of the mold  27  enters the hole (space)  13   g  of the drum supporting frame  13 , leaving a gap between itself and drum supporting frame  13 . This gap is the space  20   b  for forming the spring seat. The hole  13   g  is a through hole in the lengthwise end wall of the drum supporting frame  13  which will have the electrical contact  19 . Next, referring to  FIGS. 6 and 11(   a ), a space which would remain if the rib  13   k  were removed from the space made up of the electrical contact formation space  13   a  of the drum supporting frame  13  and the recess  27   c  of the mold  27  is the space  20   a  for contacting surface  19   a.    
     Next, referring to  FIG. 8(   d ), after the attachment of the molds  27  and  28  to the drum supporting frame  13 , the gate  30  for injecting the electrically conductive resin  34  is inserted into the hole  28   b  of the mold  28 . As the gate  30  is inserted, it comes into contact with the deepest end of the hole  28   b . Incidentally, the gate  30  may be formed as an integral part of the mold  28 . In such a case, the mold  27  is attached to the drum supporting frame  13  before the mold  28 . Moreover, the mold  28  may be eliminated. In such a case, the gate  30  is directly inserted into the resin injection opening  13   d  of the drum supporting frame  13 . Further, the tip of the gate  30  may be provided with a fringe wall (sealing wall) which airtightly meets the surface  13   d  of the drum supporting frame  13 , which has the resin injection opening  13   d  so that the joint between the tip and the resin injecting hole  13   d  will remain airtightly sealed when the electrically conductive resin  34  is injected. 
     Next, referring to  FIG. 14(   b ), the electrically conductive resin  34  is injected into the tunnel-shaped runner  13   c  of the drum supporting frame  13  through the resin injection opening  28   b . Then, the electrically conductive resin  34  advances through the tunnel-shaped runner  13   c  of the drum supporting frame  13 , and reaches a fork  13   h  of the runner  13   c . Then, a part of the body of resin electrically conductive resin  34  flows into the spring seat formation space  13   b  of the drum supporting frame  13 , the rest advances further through the tunnel-shaped runner  13   c , reaching thereby the contact surface formation space  13   a  of the drum supporting frame  13 . Therefore, the contact surface formation space  20   a  and spring seat formation space  20   b  are filled up with the electrically conductive resin  34 . 
       FIG. 14(   c ) is a perspective/sectional view of the combination of the drum supporting frame  13 , backing member  37 , mold  28 , gate  30 , and body of electrically conductive resin  34  after the injection of the electrically conductive resin  34  into the contact surface formation space  20   a  and spring seat formation space  20   b  has just been completed. Next, referring to  FIGS. 4 and 14(   c ), as the injection of the electrically conductive resin  34  is completed, the molds  27  and  28  are separated from the drum supporting frame  13 , there appear the contacting surface  19   a  formed by the body of the electrically conductive resin  34  which entered into the contact surface formation space  20   a , and charge roller contact point  19   b  formed by the body of electrically conductive resin  34 , which entered into the spring seat formation space  20   b . The contacting surface  19   a  and charge roller contact point  19   b  are formed as integral parts of the drum supporting frame  13  by the bodies of electrically conductive resin  34  which enter the two spaces  20   a  and  20   b  through the above described routes (runner  13   c ). As for the aforementioned rib  13   k , it remains within the electrical contact  19 . Further, referring to  FIG. 5 , the tunnel-shaped runner  13   c , which extends between the resin injection opening  13   d  of the drum supporting frame  13  to the contacting surface formation space  13   a  is within the wall of the drum supporting frame  13 . 
     Next, referring to  FIG. 9 , the process for separating the molds  27  and  28  from the drum supporting frame  13  is described. To begin with, referring to  FIG. 9(   a ), the gate  30  is retracted from the resin injection opening  28   b  of the mold  28  (direction indicated by arrow mark in  FIG. 9(   a )). Next, referring to  FIG. 9(   c ), the mold  27  and backing member  37  are separated from the drum supporting frame  13  (direction indicated by arrow mark in  FIG. 9(   c )). Lastly, referring to  FIG. 9(   d ), the mold  28  is separated from the drum supporting frame  13  (direction indicated by arrow mark in  FIG. 9(   d )), exposing the electrical contact  19  (having contacting surface  19   a , charge roller contact point  19   b ) formed as an integral part of the drum supporting frame  13 . 
     In the case where the mold  28  is not used, the gate  30  is retracted from the drum supporting frame  13  after the injection of the electrically conductive resin  34 . Then, the mold  27  and backing member  37  are retracted in the listed order. With the use of the above described method, the electrical contact  19  (having contacting surface  19   a , charge roller contact point  19   b ) can be formed as an integral part of the drum supporting frame  13 . 
     (9) Shape, Function and Electrical Resistance of Each Point (Surface) of Contact 
     Next, referring to  FIGS. 5 ,  12  and  13 , the shape of the electrical contact  19  is described.  FIGS. 12(   a ) and  12 ( b ) are drawings for describing the functions of the electrical contact  19  having appeared as the molds  27  and  28  are separated from the drum supporting frame  13 .  FIGS. 12(   a ) and  12 ( b ) do not show the drum supporting frame  13 .  FIG. 12(   c ) is a sectional view of the electrical contact  19  at a plane which coincides with a line P-P in  FIG. 12(   b ).  FIG. 12(   d ) is a sectional view of the electrical contact  19  at a plane which coincides with a line Q-Q in  FIG. 12(   b ).  FIG. 12(   e ) is a sectional view of the electrical contact  19  at a plane which coincides with a line R-R in  FIG. 12(   b ).  FIG. 12(   f ) is a sectional view of the electrical contact  19  at a plane which coincides with a line S-S in  FIG. 12(   b ).  FIGS. 13(   a ) and  13 ( b ) are similar to  FIGS. 12(   a ) and  12 ( b ), respectively, except that  FIGS. 13(   a ) and  13 ( b ) show the main assembly electrode  21 , compression spring  22   a , and charge roller terminal  23   a.    
     Referring to  FIGS. 12(   a ) and  12 ( b ), the electrical contact  19  has the contacting surface  19   a  and charge roller contact point  19   b . Next, referring to  FIGS. 13(   a ) and  13 ( b ), as the process cartridge B is installed into the main assembly  100  of the image forming apparatus A, the contacting surface  19   a  comes into contact with the main assembly electrode  21 . Then, as the charge roller  18  is attached to the drum supporting frame  13 , the metallic charge roller axle  18   a  comes into contact with the charge roller terminal  23   a , and the charge roller  18  is rotatably supported by the drum supporting frame  13 . 
     Thus, an electricity passage is established between the main assembly electrode  21  and metallic charge roller axle, by the compression spring  22   a  (which is in contact with the charge roller terminal  23   a ), charge roller contact point  19   b  (which is in contact with the compression spring  22   a ), runner section  19   c , and contacting surface  19   a . The surface of the electrical contact  19 , which comes into contact with the main assembly electrode  21  does not need to be the contacting surface  19   a . For example, it may be the surface  19   e.    
     Next, the cross-sectional shape of the portion of the electrical contact  19 , which corresponds in position to the runner  13   c  of the drum supporting frame  13  is described. Referring to  FIGS. 5(   c ),  5 ( d ) and  5 ( e ), and  FIG. 12 , the electrical contact  19  (having contacting surface  19   a  and charge roller contact point  19   b ) is different in cross-sectional shape from the runner section  19   c . Here, the “cross-sectional shape” means the shape of the cross section of the runner section  19   c  at a plane which coincides with the lines P-P, Q-Q, R-R or S-S shown in  FIG. 12(   b ), for example. That is, in this embodiment, the cross sections of the electrical contact  19 , at planes corresponding to lines P-P, Q-Q, R-R and S-S in  FIGS. 12(   c )- 12 ( f ), are different in shape. Further, the direction in which the electrically conductive resin  34  flows in the runner  13   c  from gate  30 , is different from the directions  19   h  and  19   i  in which the electrically conductive resin  34  flows out of the runner  13   c  to form the contacting surface  19   a  and charge roller contact point  19   b.    
     Therefore, the runner section  19   c  becomes different in the distribution of electrically conductive substance in the electrically conductive resin  34  from the contacting surface  19   a  and charge roller contact point  19   b . In other words, in this embodiment, the electrical contact  19  (electrical contact formation mold) is designed to make the electrically conductive resin  34  change in direction as the electrically conductive resin  34  flows through the runner  13   c  and electrical contact formation space (mold), so that the electrically conductive substance in the electrically conductive resin  34  is disturbed (stirred) as it flows through the runner  13   c  and electrical contact formation space. If the electrical contact  19  is formed of the electrically conductive resin  34  when the resin  34  is nonuniform in the distribution of the electrically conductive substance, it is possible that the resultant electrical contact  19  will be higher in electrical resistance (resistance value, hereafter) than intended. In this embodiment, however, the electrically conductive substance in the electrically conductive resin  34  is prevented from being unevenly settling in the electrically conductive resin  34  as described above. Therefore, its electrical resistance remains as intended; it remains at an intended level. Here, the “orientation” of the flow of the electrically conductive resin  34  means the direction in which the electrically conductive resin  34  flows, and also, the directions in which the body of electrically conductive resin  34  expands, as the electrically conductive resin  34  accumulates in the electrical contact formation space. 
     Generally speaking, while a body of electrically conductive resin cools to solidify after its injection into a given space, the electrically conductive particles (carbon black particles, which will be described later) in the resin move into the portion of the resin, which is slower to lose heat than the rest (peripheral portion in terms of cross section). Thus, the surface layer of the body of electrically conductive resin  34  reduces in the amount of electrically conductive particles. For example, in a case where a cylindrical component, which is uniform in terms of the diameter, is formed of resinous compound which contains electrically conductive particles, the particles tend to collect in the center portion of the cylindrical component, regardless of the lengthwise direction of the component (direction parallel to generatrix of cylindrical component). In other words, the surface layer of the cylindrical component tends to reduce in the amount of electrically conductive particles. Thus, the resultant cylindrical component is higher in overall electrical resistance than intended. Further, in terms of the direction of the flow of resinous resin, the contacting surface  19   a  and charge roller contact point  19   b  are on the downstream side of the gate  19   d.    
     In this embodiment, the runner  13   c  of the drum supporting frame  13 , through which the electrically conductive resin  34  is injected into the contacting surface formation space  20   a  and charge roller contact point formation space  20   b , is designed so that as the resin flows through the runner  13   c , it is made to change in direction not only in terms of the primary direction, that is, the direction in which it advances, but also, in the secondary direction, that is, the direction perpendicular to the primary direction, by providing the runner  13   c  with bends and/or portions which are different in size in terms of cross section. Therefore, the electrical contact  19  in this embodiment is significantly more uniform in the distribution of the electrical conductive particles, being therefore better in electrical conductivity, than any of electrical contact made of electrically conductive resin, which is in accordance with the prior art. Further, forcing the electrically conductive resin  34  to change in orientation, in terms of the direction in which it is flows, changes the body of electrically conductive resin  34  in terms of which portions of the body of electrically conductive resin is slow to cool. Thus, forcing the electric conductive resin  34  to change in the direction in which it flows and/or expands can make a greater amount of electrically conductive particles in the electrically conductive resin  34  remain in the surface layer, that is, the functional layer, of the electrical contact  19  while the electrical contact  19  cools after its formation. That is, it can provide an electrical contact, the functional portions of which are as small as possible in electrical resistance. 
     Further, in this embodiment, in order to make the electrical contact  19  even better in electrical conductivity, the drum supporting frame  13  is provided with the rib  13   k . Thus, the benefit of providing the drum supporting frame  13  with the rib  13   k  is described next.  FIG. 1  is a drawing for describing the sequential steps through which the electrical contact  19  is formed in such a manner that the rib  13   k  is enveloped by the electrically conductive resin  34 . In  FIGS. 1(   a )- 1 ( c ), the left drawing is the cross-sectional view of the electrical contact  19  as seen from the front side of the apparatus, and the right drawing is the sectional view of the electrical contact  19  as seen from the direction perpendicular to the axial line of the photosensitive drum  7 . More specifically, the left drawing of  FIG. 1(   a ) is a plan view of the rib  13   k  of the drum supporting frame  13  and its adjacencies, and the right drawing is a sectional view of the combination of the mold  27  and the portion of the drum supporting frame  13 , which has the rib  13   k , at a plane parallel to the axial line of the drum  7  after the attachment of the mold  27  to the drum supporting frame  13 . When the combination is in the state shown in  FIG. 1(   a ), the rib  13   k  is within the recess  27   c  of the mold  27 .  FIG. 1(   b ) shows the body of electrically conductive resin  34  which is flowing in the recess  27   c  of the mold  27  around the rib  13   k . The electrically conductive resin  34  flows in the direction indicated by arrow marks  19   k  and  19   l  in  FIG. 1(   b ), while filling the recess  27   c .  FIG. 1(   c ) is a drawing which shows the recess  27   c  of the mold  27  after the recess  27   c  was filled up with the electrically conductive resin  34 , that is, after the electrical contact  19  was formed in the recess  27   c.    
     As described above, in a case where the drum supporting frame  13  and mold  27  are structured so that as they are joined, the rib  13   k  of the drum supporting frame  13  protrudes into the recess  27   c  (space for forming contacting surface  19   a , which is at the inward end of the runner  13   c , the electrically conductive resin  34  flows in a manner to envelop the rib  13   k  (in directions indicated by arrow marks  19   k  and  19   l ). That is, the directions in which the electrically conductive resin  34  flows in the recess  27   c  are different from the one (indicated by arrow mark  19   i ) in which the electrically conductive resin  34  flows before it enters the recess  27   c . In other words, the electrically conductive resin  34  is stirred even in the recess  27   c , being thereby disturbed in terms of the distribution of the electrically conductive particles. Also in this embodiment, the rib  13   k  causes the body of the electrically conductive resin  34  to branch at the rib  13   k , and then, rejoin at the downstream side of the rib  13   k . Thus, the electrically conductive resin  34  is made even more disturbed (homogenous) in terms of the distribution of its electrical conductive particles. Referring to  FIG. 1(   b ), as a body of electrically conductive resin  34  is flowed into the recess  27   c , it is allowed to flow in various directions different from the direction in which it flowed into the recess  27   c , in such a manner to envelop the rib  13   k : it is made more homogenous in terms of the distribution of the electrically conductive particles. 
     Further, the electrical contact  19  formed with the presence of the rib  13   k  in the recess  27   c  of the mold  27  is different from an electrical contact ( 19 ) formed without the rib  13   k  in the recess  27   c , in the locations which are slower in the speed with which they reduce in temperature while the electrical contact ( 19 ) cools. More specifically, in the case where the rib  13   k  is not present in the recess  27   c , the center portion of the contacting portion  19   a  is slower in cooling speed than the peripheral portion. Therefore, it is possible that the electrically conductive particles will congregate into the center portion (portion which does not come into contact with main assembly electrode), reducing thereby the surface layer of the contacting portion  19   a  in the amount of the electrically conductive particles. In comparison, in the case where the rib  13   k  is present in the recess  27   c , the center portion of the contacting portion  19   a , that is, the portion of the contacting portion  19   a , which is next to the rib  13   k , is faster in cooling speed than the center portion of the contacting portion ( 19   a ) formed without the rib  13   k . Therefore, the contacting portion  19   a  is practically uniform in cooling speed. Therefore, the electrically conductive particles are unlikely to concentrate in the center portion, that is, it is unlikely for the surface layer to become significantly smaller in the amount of the electrically conductive particles. 
     As described above, in this embodiment, the drum supporting frame  13  and mold  27  are structured so that as the drum supporting frame  13  and mold  27  are joined, the rib  13   k  of the drum supporting frame  13  will protrude into the recess  27   c  of the mold  27 , that is, the contacting portion formation space, which is in connection to the inward end of the runner  13   c  of the drum supporting frame  13 . Therefore, the electrical contact  19  in this embodiment is significantly more even in the distribution of the electrical conductive particles, being therefore lower in electrical resistance and therefore, better in conductivity, than any electrical contact ( 19 ) designed and formed in accordance with the prior art. Further, in the case of the electrical contact  19  in this embodiment, the electrical contact  19  envelops the rib  13   k  of the drum supporting frame  13 . Thus, the rib  13   k  reinforces the electrical contact  19 , preventing the problem that it is made to collapse by its contraction which occurs after its formation and/or breaks away with the mold  27  when the mold  27  is separated from the drum supporting frame  13 . Therefore, the electrical contact  19  in this embodiment is significantly higher in positional accuracy than any conventional electrical contact ( 19 ), which protrudes from the drum supporting frame  13  and is formed of electrically conductive resin alone (without rib  13   k ). 
     In the first embodiment described above, the contacting surface  19   a  and charge roller contact point  19   b  are made different in cross-sectional shape from the runner  13   c  of the drum supporting frame  13 , and the drum supporting frame  13  is provided with the rib  13   k , as shown in  FIG. 12 . However, if a sole objective is to produce an electrical contact which is significantly more uniform in the distribution of electrically conductive particles, all that is necessary is to provide the drum supporting frame  13  with the rib  13   k , and for the position the rib  13   k  to protrude into the recess  27   c  of the mold  27 . That is, even if it is impossible to design the drum supporting frame  13  so that its runner  13   c  is nonuniform in the width in terms of the direction of the resin flow, an electrical contact ( 19 ) which is virtually uniform in the distribution of the electrically conductive particles, being therefore lower in electrical resistance and therefore, better in conductivity, can be obtained by providing the drum supporting frame  13  with such a rib as the rib  13   k  in this embodiment which is positioned as described above. Further, in this embodiment, the rib  13   k  is positioned so that it will be at the downstream end of the runner  13   c  in terms of the direction of the resin flow. However, this embodiment is not intended to limit the present invention in terms of the shape and positioning of the rib  13   k . All that is required of the rib  13   k  regarding its shape and positioning is that the rib  13   k  is shaped and positioned so that the electrical contact  19  (electricity passage) formed with the presence of the rib  13   k  is significantly smaller in electrical resistance than an electrical contact ( 19 ) formed without the presence of the rib  13   k . For example, the rib  13   k  may be positioned so that it will be within the runner  13   c  (runner section  19   c : electricity passage between the contacting surface  19   a  and charge roller contact point  19   b ). 
     (10) Mold Clamping and Backing Up 
     Next, referring to  FIGS. 6 ,  7 ,  8 ,  14  and  15 , mold clamping which occurs when the contacting surface  19   a  and charge roller contacting point  19   b  are formed is described.  FIG. 15  is a schematic sectional view of the combination of the backing member  37 , drum supporting frame  13 , electrical contact  19 , mold  28 , gate  30 , and electrically conductive resin  34 , which is for describing the resin pressure. 
     When the electrical contact  19  is formed with the use of the molds  27  and  28 , first, the mold  27  is attached to the drum supporting frame  13  in such an attitude that the surface  27   a  of the mold  27  meets the surface  13   e  of the drum supporting frame  13 , Then, the mold  27  is clamped to the drum supporting frame  13 . Further, the mold  28  is attached to the drum supporting frame  13  in such an attitude that the surface  28   a  of the mold  28  meets the surface  13   f  of the drum supporting frame  13 . Then, the mold  28  is clamped to the drum supporting frame  13 . More specifically, the backing member  37  is placed in contact with the opposite portion of the drum supporting frame  13  from the surfaces  13   e  and  13   f , so that the drum supporting frame  13  is backed up by the backing member  37 , in order to prevent the surfaces  13   e  and  13   f  of the drum supporting frame  13 , being displaced and/or separated from the surfaces  27   a  and  28   a  of the molds  27  and  28 , respectively, by the pressure applied to the molds  27  and  28 , and/or the pressure P (resin pressure) generated in the electrically conductive resin  34  when the electrically conductive resin  34  is injected into the electrical contact formation space (mold), and also, to prevent the drum supporting frame  13  from being deformed by the pressure P. 
     In this embodiment, the drum supporting frame  13  is backed up by the backing member  37 , by its opposite portions from the surfaces  13   e  and  13   f  of the drum supporting frame  13 . However, the portions by which the drum supporting frame  13  is backed up by the backing member  37  do not need to be the portions by which the drum supporting frame  13  is backed up by the backing member  37  in this embodiment. All that is necessary is that the portions of the drum supporting frame  13  by which the drum supporting frame  13  is backed up by the backing member  37  are such portions that can prevent the drum supporting frame  13  from being displaced or deformed. Also in this embodiment, the electrical contact  19  is for providing electrical connection between the charge roller  18  in the latent image forming section D of the process cartridge B, and the main assembly electrode  21 . However, this embodiment is not intended to limit the present invention in terms of the role (function) of the electrical contact  19 . That is, the present invention is also applicable to an electrical contact which provides electrical connection between the photosensitive drum  7  and the main assembly  100  of the image forming apparatus A, and also, between the charge roller  13  and the main assembly  100 . That is, the present invention is also applicable to an electrical contact having a point of contact which provides electrically connection between the charge roller  18  and main assembly  100 , and a point of contact which provide electrical connection between the photosensitive drum  7  and main assembly  100 . Further, not only is the present invention applicable to the process cartridge (B) structured so that the charge roller  18  and/or photosensitive drum  7  is in electrical connection with the electrical contact  19  through the compression spring  22 , or in direct electrical connection to each other. Further, in this embodiment, the electrical contact  19  is a part of the latent image forming section D. However, the present invention is also applicable to the electrical contact ( 19 ) of the development section C. 
     In this embodiment, the material for the electrical contact  19  is polyacetal compound which contains carbon black by 10%. The reason why carbon black is used as electrically conductive material is to minimize the damage (frictional wear and the like) to production apparatuses. However, the substance to be used as the electrical conductive material may be carbon fiber, metallic additive, etc. 
       FIG. 16  is a drawing for describing a case in which an electrical contact  26  is formed as an integral part of the frame  8  of the development cartridge. Electrically conductive resin  34  is injected into the electrical contact formation space through a runner  8   a  (gate). The runner  8   a  branches at a fork  26   bc , into a resin passage which leads into the space for forming a surface  26   ba  which comes into contact with the main assembly electrode  21  of the main assembly  100  of the image forming apparatus A, and a resin passage which leads into a development roller supporting portion  26   bb . The main assembly contacting portion  26   ba  is at the tip of the projection  26   bg  which projects from the surface of the development cartridge frame  8 . The development roller supporting portion  26   bb  is in contact with the metallic core  12   a  of the development roller  12 , and rotatably supports the metallic core  12   a  (development roller  12 ). Thus, electrical connection is provided between the main assembly  100  of the image forming apparatus A and development roller  12  through the main assembly contacting surface  26   ba , developer supporting portion  26   bb , and metallic core  12   a  of the development roller  12 . 
     In the case of the electrical contact  26  structured as shown in  FIG. 16 , as the electrically conductive resin  34  is injected into the electrical contact formation space through the runner  8   a  (gate), the electrically conductive resin  34  is changed in the direction (directions indicated by arrow marks  26   bd  and  26   be  in  FIG. 16(   b )) by multiple (two) ribs  8   b  and  8   c  with which the development cartridge frame  8  is provided. Therefore, it is made to remain as uniform in the distribution of electrical conductive particles as possible. Further, in the case of the electrical contact  26  structured as shown in  FIG. 16 , the electrical contact  26  is formed as an integral part of the frame  8  of the development cartridge. However, the present invention is also applicable to an electrical contact which is an integral part of a component which supports the development roller  12  or toner supply roller  16 . The electrical connection between the development roller  12  and electrical contact  26  may be through the compression spring  22  as that between the electrical contact  19  and the main assembly electrode  21 , as described above. 
     As described above, in this embodiment, the drum supporting frame  13  is provided with the rib  13   k , and the mold  27  is structured so that the electrically conductive resin  34  will flow in a manner to envelop the rib  13   k . Therefore, the electrically conductive particles in the electrical contact  19  in this embodiment remain more randomly (uniformly) distributed in the electrical conductive resin  34  than in any electrical conductive contact in accordance with the prior art, which is formed of electrically conductive resin. Therefore, the electrical contact  19  in this embodiment is significantly lower and stable in electrical resistance, and therefore, better in electrical conductivity, than any electrical contact in accordance with the prior art, which is formed of electrically conductive resin and is an integral part of the drum supporting frame  13 . 
     In a case of an electrical contact which projects from the drum supporting frame  13 , or development roller supporting frame, in the same direction as the direction in which the mold is removed, if the mold therefor is separated from the drum supporting frame  13  or the like before it sufficiently cools after its formation, it is possible for the electrical contact, or a part of it, to remain adhered to the mold and break off from the mold. Therefore, the electrical contact has to be allowed to cool for a substantial length of time, which adds to production cost. Further, it is possible for the electrical contact to be deformed by its shrinking which occurs when the electrical contact is allowed to naturally cool after its formation. It is also possible that as the process cartridge B is subjected to a substantial amount of impact during its shipment, the electrical contact will break off or separate from the frame to which it belongs. 
     In comparison, the electrical contact  19  in this embodiment is formed so that it envelops the rib  13   k  of the drum supporting frame  13 . Therefore, the rib  13   k  reinforces the electrical contact  19 , making it unlikely for the electrical contact  19  to be felled by its contraction which occurs to the electrical contact  19  after its formation, or to be deformed and/or partially separated from the frame  13  when the mold therefor is separated from the drum supporting frame  13 , or the like. 
     That is, this embodiment of the present invention can substantially reduces the length of time necessary to cool the electrical contact, and therefore, can reduce the manufacturing cost for the electrical contact (process cartridge). Further, it can prevent the problem that as a process cartridge is subjected to impact during its shipment, its electrical contact falls off or becomes separated from its base. Further, the electrical contact in this embodiment is, and remains, more accurately positioned than an electrical contact in accordance with the prior art, which is made of the electrically conductive resin  34  alone, that is, without the presence of a projection ( 13   k ) which projects from the side wall of the drum supporting frame  13 . 
     [Embodiment 2] 
     Next, referring to  FIGS. 17 ,  18 ,  19  and  20 , the second embodiment of the present invention is described. In the first embodiment described above, the rib which functions as a reinforcement for the electrical contact  19  was an integral part of the drum supporting frame  13 . However, in a case where a rib which is made to protrude into the recess  27   c  of the mold  27  is intended only to keep the electrically conductive resin  34  as homogenous as possible in terms of the distribution of the electrically conductive particles, it does not need to be formed as an integral part of the drum supporting frame  13 ; it may be formed as an integral part of the mold  27 . 
     In this embodiment, the rib is formed as an integral part of the mold  27 . In the following description of the second embodiment, only the structural components of the process cartridge B, which are different in structure from the counterparts in the first embodiment, are described; the structural components in the second embodiment which are similar to the counterparts in the first embodiment are not going to be described. 
       FIGS. 17(   a ) and  17 ( b ) are schematic perspective view of the combination of the main assembly electrode  21 , compression spring  22   a , and charge roller terminal  23   a , in addition of the electrical contact  19  in this embodiment, as seen from the top and bottom sides, respectively, of the combination.  FIG. 18  is a perspective view of the mold  27  (electrical contact formation mold) in this embodiment.  FIG. 19  is a perspective/sectional view of the combination of the lengthwise end of the drum supporting frame  13 , mold  28  (resin injection gate), backing member  37 , and electrically conductive resin  34 , in the second embodiment, after the injection of the electrically conductive resin into the electrical contact formation space formed between the drum supporting frame  13  and mold  27 .  FIG. 20(   b ) is a schematic perspective view of the combination of the drum supporting frame  13 , mold  27 , mold  28 , and backing member  37 , after the separation of the molds  27  and  28  and backing member  37  from the drum supporting frame  13 , which occurred after the injection of the electrically conductive resin  34  (formation of the electrical contact  19 ). 
     Referring to  FIG. 18 , the mold  27  is provided with a rib  27   d , which protrudes into the recess  27   c  of the mold  27 . Next, referring to  FIG. 20(   a ), when the electrical contact  19  is formed, the molds  27  and  28 , and backing member  37  are placed airtightly in contact with the drum supporting frame  13 . Then, the electrically conductive resin  34  is injected into the electrical contact formation space which is formed by the drum supporting frame  13  and mold  27 , and into which the rib  27   d  is protruding, as shown in  FIG. 19 . Then, the molds  27  and  28  and backing member  37  are separated from the drum supporting frame  13 , to expose the electrical contact  19  which became an integral part of the drum supporting frame  13   f , as shown in  FIG. 20(   b ). 
     Referring to  FIG. 17 , as the process cartridge B is installed into the main assembly  100  of the image forming apparatus A, the contacting surface  19   a , that is, the end surface of the portion  19   g  of the electrical contact  19 , which is protruding from the surface of the drum supporting frame  13 , comes into contact with the main assembly electrode  21 . Here, the surface of the electrical contact  19 , by which the electrical contact  19  comes into contact with the main assembly electrode  21 , does not have to be the surface  19   a . That is, it may be any surface of the electrical contact  19 . For example, it may be the surface  19   e  of the electrical contact  19 . 
     As described above, in this embodiment, the electrically conductive resin  34  is changed in the direction in which it flows, by providing the mold  27  with the rib  27   d . Thus, the electrical contact  19  in this embodiment is significantly more homogenous in the distribution of the electrically conductive particles, being therefore significantly lower in electrical resistance, and therefore, being better in electrical conductivity, than any electrical contact ( 19 ) in accordance with the prior art, which are formed of a resinous compound which contains electrically conductive substance (particles). Further, in the preceding embodiment described above, the portion of the electrical contact  19 , which contacts the main assembly electrode  21 , projects from the surface of the drum supporting frame  13 . However, the drum supporting frame  13  and electrical contact  19  may be designed so that the electrical contact  19  projects from the bottom surface of the recess with which the surface of the drum supporting frame  13  is provided. 
     According to the present invention, it is possible to provide a process cartridge, the electrical contact of which is formed of electrically conductive resin, and is significantly lower in electrical resistance than any electrical contact in accordance with the prior art, which is formed of electrically conductive resin. 
     While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims. 
     This application claims priority from Japanese Patent Application No. 277467/2011 filed Dec. 19, 2011, which is hereby incorporated by reference.