Abstract:
A cartridge detachably mountable to a main assembly of an image forming apparatus, the main assembly including a main assembly electrical contact, includes a roller including an electroconductive shaft, the roller being rotatable with the shaft; and a supporting member rotatably supporting the shaft and provided with a hole portion for exposing a part of a surface of a longitudinal end of the shaft to directly contact the part to the main assembly electrical contact and an end surface positioning portion for determining a position of the end surface with respect to a longitudinal direction of the shaft by contacting another part of the end surface.

Description:
FIELD OF THE INVENTION AND RELATED ART 
       [0001]    The present invention relates to a process cartridge removably mountable in the main assembly of an electrophotographic image forming apparatus. 
         [0002]    In the field of an electrophotographic image forming apparatus, it is common practice to employ a cartridge system, which integrally places an electrophotographic photosensitive member, and one or more means for processing the electrophotographic photosensitive member, in a cartridge, so that the electrophotographic photosensitive member and processing means can be removably mountable in the main assembly of an electrophotographic image forming apparatus. 
         [0003]    A cartridge system makes it possible for users to maintain an electrophotographic image forming apparatus by themselves, that is, without relying on a service person. Thus, the employment of a cartridge system can drastically improve an electrophotographic image forming apparatus in terms of operational efficiency. This is why a cartridge system has come to be widely used in the field of electrophotographic image forming apparatus. 
         [0004]    A process cartridge has rotational rollers, such as a charge roller for uniformly charging the peripheral surface of a photosensitive member, and a development roller for developing an electrostatic latent image formed on the photosensitive member. A process cartridge has also input electrical contacts, which are connected to the electrical contacts, with which the main assembly of an electrophotographic image forming apparatus is provided. The input electrical contacts are in connection with the abovementioned rollers. Thus, as a process cartridge is mounted into the main assembly of the image forming apparatus, electrical connection is made between the process cartridge and main assembly, enabling the rollers to be supplied with the electric voltage from the main assembly. 
         [0005]    For example, in the case of the image forming apparatus structure disclosed in Japanese Laid-open Patent Application 2004-126030, the input electrical contacts, which are to be in contact with the rotational rollers, are solidly attached to the cartridge. Thus, it becomes possible for voltages to be supplied from the main assembly of the image forming apparatus to the cartridge, by placing these input electrical contacts in contact with the electrical contacts, with which the main assembly of the image forming apparatus are provided. 
         [0006]    Further, in the case of the image forming apparatus structure disclosed in Japanese Laid-open Patent Application 2005-258145, the cartridge is provided with guiding portions for guiding the electrical contacts, which the main assembly of the image forming apparatus has, to the input electrical contacts, which the cartridge has. 
         [0007]    In the case of the conventional technologies described above, it is made possible to reliably supply a cartridge with the voltages from the main assembly of an image forming apparatus, by connecting the electrical contacts solidly attached to the cartridge so that they remain in contact with the rollers in the cartridge even when the rollers are rotating, with the electrical contacts which the main assembly has. 
       SUMMARY OF INVENTION 
       [0008]    The object of the present invention is to simplify an electrophotographic image forming apparatus in structure, and also, to reduce an electrophotographic image forming apparatus in cost, by reducing the number of components related to the electrical connection between the main assembly of the image forming apparatus and the cartridges therefor, without interfering with the reliable supply of voltage from the main assembly of the image forming apparatus to the cartridge. 
         [0009]    According to an aspect of the present invention, there is provided a cartridge detachably mountable to a main assembly of an image forming apparatus, the main assembly including a main assembly electrical contact, said cartridge comprising a roller including an electroconductive shaft, said roller being rotatable with said shaft; and a supporting member rotatably supporting said shaft and provided with a hole portion for exposing a part of a surface of a longitudinal end of said shaft to directly contact the part to the main assembly electrical contact and an end surface positioning portion for determining a position of the end surface with respect to a longitudinal direction of said shaft by contacting another part of said end surface. 
         [0010]    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 DRAWINGS 
         [0011]      FIGS. 1(   a ) and  1 ( b ) are perspective views of the supporting member for supporting the toner supply roller and development roller. 
           [0012]      FIGS. 2(   a ) and  2 ( b ) are enlarged sectional views of the essential portions of the development cartridge and rotary. 
           [0013]      FIGS. 3(   a ) and  3 ( b ) are also enlarged sectional views of the essential portions of the development cartridge and rotary. 
           [0014]      FIGS. 4(   a ) and  4 ( b ) are sectional views of the development cartridge. 
           [0015]      FIG. 5  is a sectional view of the main assembly, development cartridge, and process cartridge of the image forming apparatus. 
           [0016]      FIG. 6  is a sectional view of the main assembly, development cartridge, and process cartridge of the image forming apparatus. 
           [0017]      FIG. 7  is a sectional view of the main assembly, development cartridge, and process cartridge of the image forming apparatus. 
           [0018]      FIGS. 8(   a ) and  8 ( b ) are perspective views of the toner supply roller and development roller, respectively, and  FIG. 8(   c ) is an exploded perspective view of the development cartridge, which shows the structure thereof. 
           [0019]      FIG. 9  is a sectional view of the electrophotographic image forming apparatus, and shows the general structure of the apparatus. 
           [0020]      FIG. 10  is a sectional view of the electrophotographic image forming apparatus, and shows the general structure of the apparatus. 
           [0021]      FIG. 11  is a sectional view of the electrophotographic image forming apparatus, and shows the general structure of the apparatus. 
           [0022]      FIG. 12  is a sectional view of the electrophotographic image forming apparatus, and shows the general structure of the apparatus. 
           [0023]      FIG. 13  is a perspective view of the combination of the rotary and one of the development cartridges. 
           [0024]      FIG. 14  is an enlarged schematic sectional view of the essential portions, inclusive of the electrical contacts of the main assembly, of the rotary, as seen from the direction from which the development cartridge is mounted, prior to the mounting of the development cartridge. 
           [0025]      FIG. 15  is an enlarged schematic sectional view of the essential portions, inclusive of the electrical contacts of the main assembly, of the rotary and development cartridge, as seen from the direction from which the development cartridge is mounted, when the development cartridge is in the main assembly. 
           [0026]      FIG. 16  is an enlarged schematic sectional view of the essential portions, inclusive of the electrical contacts of the main assembly, of the rotary and development cartridge, as seen from the direction from which the development cartridge is mounted, when the development cartridge is in the main assembly. 
           [0027]      FIG. 17  is an enlarged schematic sectional view of the end of the development roller of the development cartridge, as seen from the direction from which the development cartridge is mounted. 
           [0028]      FIG. 18  is an enlarged schematic sectional view of the essential portions, inclusive of the electrical contacts of the main assembly, of the development cartridge, as seen from the direction perpendicular to the direction from which the development cartridge is mounted, prior to the mounting of the development cartridge. 
           [0029]      FIG. 19  is a sectional view of the process cartridge  39 . 
           [0030]      FIG. 20(   a ) is a perspective view of the charge roller, and  FIG. 20(   b ) is an exploded perspective view of the process cartridge, which shows how the roller is supported. 
           [0031]      FIG. 21  is a sectional view of the electrophotographic image forming apparatus, and shows the general structure thereof. 
           [0032]      FIGS. 22(   a ),  22 ( b ), and  22 ( c ) are schematic enlarged sectional views of the electrical contacts of the main assembly, as seen from the direction from which the process cartridge is mounted, prior to, during, and after the proper mounting of the process cartridge, respectively. 
           [0033]      FIG. 23  is a perspective view of the charge roller supporting member of the process cartridge. 
           [0034]      FIGS. 24(   a ),  24 ( b ), and  24 ( c ) are enlarged sectional views of the lengthwise end of the charge roller of the process cartridge, as seen from the direction from which the process cartridge is mounted. 
           [0035]      FIG. 25  is a schematic side view of the charge roller and its adjacencies, which shows one of the examples of the structural arrangement for applying force to the charge roller in the direction parallel to the axial line of the charge roller. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0036]    Hereinafter, the cartridge in this embodiment of the present invention, which is removably mountable in the main assembly of an electrophotographic image forming apparatus, will be described along with the main assembly, in which the cartridge is removably mountable, with reference to the appended drawings. 
         [0037]    Here, a “cartridge” means a development cartridge for developing an electrostatic latent image on an electrophotographic photosensitive member. It includes a process cartridge, that is, a cartridge which has an electrophotographic photosensitive member as well as processing means, such as a developing means, for processing the electrophotographic photosensitive member. These cartridges are removably mounted in the main assembly of an electrophotographic image forming apparatus by a user. 
         [0038]    Further, an “electrophotographic image forming apparatus” means an apparatus which forms an image on recording medium with the use of an electrophotographic image forming method. As examples of an electrophotographic image forming apparatus, an electrophotographic copying machine, an electrophotographic printer (LED printer, a laser beam printer, etc.), a facsimile apparatus, a word processor, etc., can be included. 
         [0039]    The abovementioned “recording medium” means a sheet of medium, on which an image can be formed. It includes a sheet of paper, an OHP sheet, etc. 
         [0040]    Further, the “main assembly” of an electrophotographic image forming apparatus means what remains after the removal of a cartridge (cartridges) from an electrophotographic image forming apparatus. 
       Embodiment 1 
       [0041]    Hereafter, referring to  FIGS. 1-18 , the development cartridge, in this embodiment, which is removably mountable in the main assembly of an electrophotographic image forming apparatus, will be described. 
       (Overall Structure of Electrophotographic Image Forming Apparatus) 
       [0042]    First, referring to  FIGS. 5 ,  6 , and  7 , the overall structure and image forming operation of the electrophotographic image forming apparatus (which hereafter will be referred to simply as image forming apparatus) in this embodiment will be described.  FIGS. 5 ,  6 , and  7  are sectional views of the combination of the main assembly  38  of the image forming apparatus (which hereafter may be referred to as apparatus main assembly  38 ), development cartridge  5 , and process cartridge  39 . 
         [0043]    The image forming apparatus shown in  FIG. 5  is a full-color laser beam printer, which is based on four primary colors, and, the main assembly  38  of which is structured so that four development cartridges  5  ( 5   a ,  5   b ,  5   c , and  5   d ) and one process cartridge  39  are removably mountable in the main assembly  38 .  FIG. 5  shows the image forming apparatus after the proper mounting of the process cartridge  39  and development cartridges  5  into the apparatus main assembly  38 . The image forming apparatus has an exposing means (laser scanner unit)  4 , which is on the top side of the process cartridge  39 . Disposed on the bottom side of the cartridges  39  and  5  is a sheet feeder cassette  11  in which sheets of recording medium (which hereafter may be referred to simply as sheets) are stored. Further, the apparatus main assembly  38  is provided with a feed roller  12 , a pair of conveyance rollers  13 , a secondary transfer roller  9 , a fixing device  14 , a pair of discharge rollers  43 , a delivery area  15   a , etc., which are positioned in the listed order, starting from the upstream side in terms of the direction in which the sheet  40  is conveyed. Incidentally, the feed roller  12 , conveyance rollers  13 , discharge rollers,  43  etc., make up the conveying means for conveying the sheet  40 . An intermediary transfer belt  7  is an intermediary transferring member for temporarily bearing and conveying the developer image formed on an electrophotographic photosensitive drum  2 , as an image bearing member, (which hereafter will be referred to simply as photosensitive drum). Further, a primary transfer roller  8  is a transfer roller for transferring (primary transfer) the developer image formed on the photosensitive drum  2 , onto the intermediary transfer belt  7 . A cleaning unit  10  is a unit for removing the developer (which hereafter may be referred to as toner) remaining on the intermediary transfer belt  7  after the primary transfer. 
         [0044]    The process cartridge  39  is a process cartridge made by integrally placing the photosensitive drum  2  and the photosensitive drum processing means, more specifically, a charging means  3  and a cleaning means  6 , in a cartridge. It is removably mountable in the apparatus main assembly  38 . The charging means  3  is for uniformly charging the photosensitive drum  2 . The cleaning means  6  is for removing the toner remaining on the photosensitive drum  2  after the primary transfer. Incidentally, the photosensitive drum  2 , charging means  3 , and cleaning means  3  may be independently placed in their own cartridges. 
         [0045]    The development cartridge  5  is a developing apparatus (developing means) for developing an electrostatic latent image formed on the photosensitive drum  2 , into a visible image with the use of color toners, the color of which corresponds to the monochromatic components of a color image, one for one. The image forming apparatus in this embodiment employs four development cartridges, more specifically, a yellow development cartridge  5   a , a magenta development cartridge  5   b , a cyan development cartridge  5   c , and a black development cartridge  5   d , as described above. The yellow development cartridge  5   a , magenta development cartridge  5   b , cyan development cartridge  5   c , and black development cartridge  5   d  are held by a rotary  1  attached to the apparatus main assembly  38  so that it is rotatable about its rotational shaft  1   a . The yellow development cartridge  5   a , magenta development cartridge  5   b , cyan development cartridge  5   c , and black development cartridge  5   d  are removably mounted in the rotary  1 . Each development cartridge has: a development roller  21  for developing the electrostatic latent image formed on the photosensitive drum  2 ; and a toner supply roller  22  (developer supply roller) for supplying the development roller  21  with toner, as will be described later in detail. Referring to  FIG. 5 , the yellow development cartridge  5   a  has a development roller  21   a  and a toner supply roller  22   a . The magenta development cartridge  5   b  has a development roller  21   b  and a toner supply roller  22   b . The cyan development cartridge  5   c  has a development roller  21   c  and a toner supply roller  22   c . The black development cartridge  5   d  has a development roller  21   d  and a toner supply roller  22   d.    
         [0046]    The structural arrangements for the rotary  1  to support the yellow, magenta, cyan, and black development cartridges  5   a ,  5   b ,  5   c , and  5   d , respectively, are the same. Thus, the structural arrangements will be described with reference to the structural arrangement for the rotary  1  to support the yellow development cartridge  5   a.    
         [0047]    As the yellow development cartridge  5   a  is mounted into the rotary  1 , the rotary engaging portion  17   a  of the yellow development cartridge  5   a  engages with the development cartridge engaging member  18   a , with which the rotary  1  is provided, being thereby prevented from popping out of the rotary  1 . The development cartridge engaging member  18   a  is under the pressure generated by a spring (unshown) in the direction indicated by an arrow mark A in  FIG. 5 , that is, the direction in which it should be pressed to be engaged with the cartridge  5   a . The other cartridges  5   b ,  5   c , and  5   d  are also in engagement with the development cartridge engaging members  18   b ,  18   c , and  18   d , respectively, with which the rotary  1  is provided, being thereby prevented from popping out of the rotary  1 . 
         [0048]    First, the photosensitive drum  2  is rotated in the direction indicated by an arrow mark C in  FIG. 5 , and the intermediary transfer belt  7  is rotated in the direction indicated by an arrow mark B in synchronism with the rotation of the photosensitive drum  2 . As the photosensitive drum  2  is rotated, the peripheral surface of the photosensitive drum  2  is uniformly charged by the charging means  3 . Then, the charged portion of the peripheral surface of the photosensitive drum  2  is scanned with a beam of laser light projected by the exposing means  4 , while being modulated with the information regarding the monochromatic yellow component of the image to be formed. As a result, the electrostatic latent image corresponding to the yellow component of the image to be formed is effected on the photosensitive drum  2 . 
         [0049]    At the same time as the formation of this electrostatic latent image, the rotary  1 , which is holding the development cartridges  5   a ,  5   b ,  5   c , and  5   d , is rotated about its rotational shaft  1   a  by the driving force transmitting mechanism of the main assembly  38 , in the direction indicated by an arrow mark D in  FIG. 5 , so that the yellow development cartridge  5   a  is positioned in the development position ( FIG. 6 ), in which it opposes the photosensitive drum  2  (as shown in  FIG. 6 ). 
         [0050]    Then, a difference in potential level is provided between the photosensitive drum  2  and development roller  21   a  to make the yellow toner adhere to the latent image formed on the photosensitive drum  2 . As a result, the yellow toner is adhered to the latent image on the photosensitive drum  2 ; the latent image is developed. That is, a visible image is formed of the yellow toner on the photosensitive drum  2 . Hereafter, the toner image formed of the yellow toner will be referred to as yellow toner image. 
         [0051]    Thereafter, the yellow toner image on the photosensitive drum  2  is transferred (primary transfer) onto the intermediary transfer belt  7  by applying a voltage, which is opposite in polarity to the toner, to the primary transfer roller  8 , which is on the inward side of the loop which the intermediary transfer belt  7  forms. 
         [0052]    As the primary transfer of the yellow toner image is completed as described above, the rotary  1  rotates in the direction indicated by the arrow mark D in  FIG. 6 , by being driven by the driving force transmitting mechanism of the apparatus main assembly  38 ; the magenta, cyan, and black development cartridges  5   b ,  5   c , and  5   d , respectively, are sequentially placed in the development position, in which each development cartridge opposes the photosensitive drum  2 , so that the electrostatic latent image formation process, development process, and primary transfer process are sequentially carried out to sequentially form monochromatic magenta, cyan, and black toner images on the intermediary transfer belt  7 . As a result, four monochromatic toner images, different in color, are placed in layers on the intermediary transfer belt  7 . 
         [0053]    Next, referring to  FIGS. 5 and 6 , while the above described processes are carried out, the secondary transfer roller  9  remains separated from the intermediary transfer belt  7 , and so does the cleaning unit  10  for cleaning the intermediary transfer belt  7 . 
         [0054]    Meanwhile, the sheets  40  stored in layers in the sheet feeder cassette  11  are fed one by one into the apparatus main assembly  38  while being separated from the rest, and conveyed toward the conveyance rollers  13 . As each sheet  40  reaches the conveyance rollers  13 , the conveyance rollers  13  send the sheet  40  to the interface between the intermediary transfer belt  7  and secondary transfer roller  9 . Incidentally, the secondary transfer roller  9  is kept pressed upon the intermediary transfer belt  7 , as shown in  FIG. 7 . 
         [0055]    To the secondary transfer roller  9 , a voltage which is opposite in polarity to the toner is being applied. Thus, the four layers of monochromatic toner images, different in color, on the intermediary transfer belt  7  are transferred (secondary transfer) onto the surface of the sheet  40  as the sheet  40  is conveyed through the interface between the secondary transfer roller  9  and intermediary transfer belt  7 . 
         [0056]    After the transfer of the toner images onto the sheet  40 , the sheet  40  is sent to the fixing device  14 . In the fixing device  14 , the sheet  40  and the toner images thereon are subjected to heat and pressure. As a result, the toner images are fixed to the sheet  40 ; a multicolor (full-color) image is formed on the sheet  40 . Thereafter, the sheet  40  is discharged by the pair of discharge rollers  43  into the delivery portion  15   a , which is a part of the top portion of the external shell of the apparatus main assembly  38 . 
       (Description of Development Cartridge) 
       [0057]    The yellow, magenta, cyan, and black development cartridges  5   a ,  5   b ,  5   c , and  5   d , respectively, are the same in structure. Thus, the structure of the yellow development cartridge  5   a  will be described as an example of the development cartridge structure. Next, referring to  FIGS. 3-8 , the development cartridge structure will be described. 
         [0058]      FIGS. 4(   a ) and  4 ( b ) are sectional views of the yellow development cartridge  5   a .  FIGS. 8(   a ) and  8 ( b ) are perspective views of the toner supply roller and development roller, respectively.  FIG. 8(   c ) is a partially exploded view of the development cartridge, which is for describing the development roller supporting structure of the cartridge. 
         [0059]    The developing means container  23 , which is the framework of the yellow development cartridge  5   a , has a toner storage chamber  23   a  and a development chamber  23   b . The development chamber  23   b  has the development roller  21   a  and toner supply roller  22   a . The toner chamber  23   a  is on top of the development chamber  23   b . The two chambers  23   a  and  23   b  are separated by a toner delivery opening  23   c . Until the yellow development cartridge  5   a  reaches a user, more specifically, until it is used for the first time, the toner delivery opening  23   c  remains sealed with a toner seal  41 , which is a piece of film attached between the toner storage chamber  23   a  and development chamber  23   b  to keep the two chambers  23   a  and  23   b  separated from each other; the toner seal  41  is tightly attached to the developing means container  23  by thermal welding or the like method in a manner to block the toner delivery opening  23   c . The toner seal  41  is to be removed before the yellow development cartridge  5   a  is used for the first time. As the toner seal  41  is removed, the toner  42  in the toner storage chamber  23   a  naturally falls into the adjacencies of the development position, shown in  FIG. 6 , where the development roller  21   a  opposes the photosensitive drum  2 , as shown in  FIG. 4(   b ). 
         [0060]    The toner supply roller  22   a  is the roller for supplying the development roller  21   a  with the toner, and is made up of a sponge roller portion  22   a   1 , and an electrically conductive shaft  22   a   2 , as shown in  FIG. 8(   a ). The toner supply roller  22   a  is structured so that the sponge roller portion  22   a   1  rotates with the shaft  22   a   2 . In this embodiment, a shaft which is made of free-cutting steel (SUM24L), and is KN-plated, is used as the shaft  22   a   2 . The shaft  22   a   2  is put through the sponge roller portion  22   a   1  in the direction parallel to the lengthwise direction of the rotational axis of the toner supply roller  22   a , in such a manner that its lengthwise ends  22   a   2 L and  22   a   2 R extend from the left and right lengthwise ends of the sponge roller portion  22   a   1 , respectively. 
         [0061]    The development roller  21   a  is the roller for developing an electrostatic latent image formed on the photosensitive drum  2 . It is made up of a rubber roller portion  21   a    1  and an electrically conductive shaft  21   a   2 , as shown in  FIG. 8(   b ). The development roller  21   a  is structured so that the rubber roller portion  21   a    1  rotates with the shaft  21   a   2 . The shaft  21   a   2  is put through the rubber roller portion  21   a    1  in the direction parallel to the lengthwise direction of the rotational axis of the development roller  21   a , in such a manner that its lengthwise ends  21   a   2 L and  21   a   2 R extend from the left and right lengthwise ends of the rubber roller portion  21   a    1 , respectively. 
         [0062]    The structural arrangement for the yellow development cartridge  5   a  to support the toner supply roller  22   a , and the structural arrangement for the yellow development cartridge  5   a  to support the development roller  21   a , are the identical. Thus, the structural arrangement for the yellow development cartridge  5   a  to support the development roller  21   a  is described as an example of the structural arrangement for which the yellow development cartridge  5   a  to support its rollers. Referring to  FIG. 8(   c ), the yellow development cartridge  5   a  is rotatably supported; the lengthwise end portions  21   a   2 L and  21   a   2 R are rotatably supported by a pair of supporting members  19 L and  19 R, respectively. 
         [0063]    The toner  42  in the development chamber  23   b  is picked up by the toner supply roller  22   a . Then, as the toner supply roller  22   a  is rotated in the direction indicated by an arrow mark E in  FIG. 4(   b ), it supplies the development roller  21   a  with the toner  42 . The development roller  21   a  is rotated in the direction indicated by an arrow mark F in  FIG. 4(   b ). As the development roller  21   a  is rotated in the direction F, the toner  42  on the development roller  21  is regulated by a development blade  16 , and then, is transferred onto the photosensitive drum  2 ; the latent image on the photosensitive drum  2  is developed by the toner  42  from the development roller  21   a . After the development, the toner  42  remaining on the development roller  21   a  is removed by the toner supply roller  22   a . Then, the development roller  21   a  is supplied again with the toner  42  by the toner supply roller  22   a . In order to develop the latent image on the photosensitive drum  2 , the development roller  21   a  is supplied with the voltage from the apparatus main assembly  38 . Further, the toner supply roller  22   a  is also supplied with the voltage from the apparatus main assembly  38 . 
         [0064]    In order to ensure that the state of contact between the development roller  21   a  and photosensitive drum  2  in the development position remains stable, the rotary  1 , by which the yellow development cartridge  5   a  is held, is kept pressed toward the photosensitive drum  2 . Thus, the development roller  21   a  of the yellow development cartridge  5   a  is kept pressed upon the photosensitive drum  2  in such a manner that a preset amount of contact pressure is maintained between the development roller  21   a  and photosensitive drum  2 . 
         [0000]    (Method for Mounting Development Cartridge into Image Forming Apparatus Main Assembly, and Method for Removing Development Cartridge from Image Forming Apparatus Main Assembly) 
         [0065]    Next, referring to  FIG. 9 , the operation for mounting the yellow, magenta, cyan, and black development cartridges  5   a ,  5   b ,  5   c , and  5   d , respectively, into the apparatus main assembly  38 , and the operation for removing them from the apparatus main assembly  38 , will be described. 
         [0066]    Referring to  FIG. 9 , except during a development operation, the rotary  1  is kept on standby in one of the preset positions, into which it is rotated to keep the development roller  21  separated from the photosensitive drum  2 . For example, the position in which the black development cartridge  5   d  is kept on standby, is 40° away in the direction indicated by an arrow mark G in  FIG. 9  from the development position. As for the movement of each development cartridge into its standby position, each development cartridge is automatically moved into its standby position by the driving force transmitting mechanism after the completion of the formation of a monochromatic image for which each development cartridge is used. The position, shown in  FIG. 9 , in which the black development cartridge  5   d  is kept on standby, is the development cartridge position, into which each development cartridge is mounted, or from which each development cartridge is removed. 
         [0067]    Referring to  FIG. 10 , as a cover  20  is opened, the development cartridge engaging member  18   d  retracts in the direction indicated by an arrow mark H in  FIG. 10 , disengaging from the rotary engaging portion  17   d  of the black development cartridge  5   d . As a result, it becomes possible for the black development cartridge  5   d  to be removed from the apparatus main assembly  38  (rotary  1 ) in the direction indicated by an arrow mark I in  FIG. 10 , or mounted into the apparatus main assembly  38  (rotary  1 ) in the direction indicated by an arrow mark K in  FIG. 10 . 
         [0068]    The yellow, magenta, cyan, and black development cartridges  5   a ,  5   b ,  5   c , and  5   d , respectively, are the same in the operation for mounting them and the operation for dismounting them. Thus, the operation for mounting the yellow development cartridge  5   a  and the operation for dismounting the yellow development cartridge  5   a  will be described as an example of mounting each development cartridge and an example of dismounting each development cartridge, respectively. 
         [0069]    The yellow development cartridge  5   a  can be mounted into, or removed from, the apparatus main assembly  38  (rotary  1 ), only when the yellow development cartridge chamber is in the abovementioned mounting-and-dismounting position. As for the means for moving the yellow development cartridge chamber into the mounting-and-dismounting position, the driving force transmitting mechanism of the apparatus main assembly  38  can be used, or the rotary  1  may be manually moved into the mounting-and-dismounting position. Referring to  FIG. 11 , as the cover  20  is opened when the yellow development cartridge  5   a  (yellow development cartridge chamber) is in the mounting-and-dismounting position, the development cartridge engaging member  18   a  is made to retract in the direction indicated by the arrow mark H in  FIG. 11  by the opening movement of the cover  20 . As a result, it becomes possible for the yellow development cartridge  5   a  to be removed in the direction indicated by the arrow mark I in  FIG. 11 , or mounted in the direction indicated by the arrow mark K in  FIG. 11 . 
         [0070]    Referring to  FIG. 12 , as a user closes the cover  20 , the development cartridge engaging member  18   a  is moved in the direction indicated by an arrow mark A in  FIG. 12  by the closing movement of the cover  20 , engaging thereby the rotary engaging portion  17   a  of the yellow development cartridge  5   a . As a result, the yellow development cartridge  5   a  is prevented from popping out of the rotary  1 . 
         [0000]    (Description of Structural Arrangement for Supplying Rollers of Development Cartridge with Voltage from Image Forming Apparatus Main Assembly) 
         [0071]    Next, referring to  FIGS. 1 , and  8 ( c )- 17 , the structural arrangement for supplying the toner supply roller  22  and development roller  21  of each development cartridge  5  with the voltage from the apparatus main assembly  38  will be described. The structural arrangements for supplying the developer supply rollers  22   a ,  22   b ,  22   c , and  22   d  and development rollers  21   a ,  21   b ,  21   c , and  21   d  of the development cartridges  5   a ,  5   b ,  5   c , and  5   d , respectively, with the voltage from the apparatus main assembly  38  are the same. Thus, the structural arrangement for supplying the development roller  21   a  of the yellow development cartridge  5   a  with the voltage from the apparatus main assembly  38  will be described as an example of the structural arrangement. 
         [0072]      FIG. 1(   a ) is a perspective view of the supporting member for the toner supply roller and development roller.  FIG. 1(   b ) is a perspective view of the development cartridge.  FIGS. 9-12  are sectional views of the electrophotographic image forming apparatus, and show the general structure of the apparatus.  FIG. 13  is a perspective view of the combination of one ( 5   a ) of the development cartridges and the rotary  1 .  FIG. 14  is an enlarged schematic sectional view of the essential portions, inclusive of the electrical contacts of the main assembly, of the rotary, as seen from the direction from which the development cartridge is mounted, prior to the mounting of the development cartridge.  FIGS. 15 and 16  are enlarged schematic sectional views of the essential portions, inclusive of the electrical contacts of the main assembly, of the rotary and development cartridge, as seen from the direction from which the development cartridge is mounted, when the development cartridge is in the main assembly.  FIG. 17  is an enlarged schematic sectional view of the end of the development roller of the development cartridge, as seen from the direction from which the development cartridge is mounted. 
         [0073]    Referring to  FIG. 13 , the apparatus main assembly  38  is provided with an electrical contact  24   a  for supplying the development roller  21   a  with voltage. In this embodiment, it is the rotary  1  of the apparatus main assembly  38  that is provided with the electrical contact  24   a . The electrical contact  24   a  is positioned so that immediately after the mounting of the yellow development cartridge  5   a  into the apparatus main assembly  38 , its position coincides with that of the rotational axis J of the development roller  21   a . Incidentally, in this embodiment, an electrical contact formed of free-cutting steel (SUM24L) and KN-plated is used as the electrical contact  24   a.    
         [0074]    Next, referring to  FIG. 14 , the rotary  1  is provided with an engagement hole  1   b  in which the electrical contact  24   a  is fitted, and a regulating wall  1   c  for preventing the electrical contact  24   a  from popping out of the rotary  1  in the direction indicated by an arrow mark L in  FIG. 14 . The electrical contact  24   a  is held to the rotary  1  by a spring  24 , which is for keeping the electrical contact  24   a  pressed in the direction indicated by an arrow mark L in  FIG. 14 , and a spring cover  26 , while being allowed to move in the direction parallel to the rotational axis J of the development roller  21   a . Further, the electrical contact  24   a  is provided with a flange portion  24   a   1  for preventing the accident that as the electrical contact  24   a  is pressed against the regulating wall  1   c  of the rotary  1 , it pops out of the rotary  1  in the direction indicated by the arrow mark L in  FIG. 14 . Thus, the electrical contact  24   a  is prevented from popping out of the rotary  1  in the direction indicated by the arrow mark L in  FIG. 14 , when the yellow development cartridge  5   a  is not in the rotary  1 . 
         [0075]    Referring to  FIG. 15 , on the other hand, the supporting member  19 R of the yellow development cartridge  5   a  is provided with a regulating portion  19 R 2  for regulating the movement of the development roller  21   a  in the direction parallel to the rotational axis J of the development roller  21   a . This regulating portion  19 R 2  is the positioning portion for precisely positioning the lengthwise end surface  21   a   3  of the development roller  21   a ; as a part of the lengthwise end surface  21   a   3  of the development roller  21   a  comes into contact with the regulating portion  19 R 2 , the lengthwise end surface  21   a   3  becomes precisely positioned. The regulating member  19 R (regulating portion  19 R 2 ) is provided with a through hole  19 R 6 , through which the lengthwise end surface  21   a   3  of the development roller  21   a  is partially exposed to allow the end surface  21   a   3  to directly contact the aforementioned electrical contact  24   a  of the apparatus main assembly  38 . In other words, the supporting member  19 R has the through hole  19 R 6  for partially exposing the end surface  21   a   3 , and the regulating portion  19 R 2  (as the lengthwise end surface positioning portion) for precisely positioning the lengthwise end surface  21   a   3  by the other portion of the end surface  21   a   3 . In this embodiment, the end surface  21   a   3 , through which the development roller  21   a  is provided with electric power, is precisely positioned by the electrical contact  24   a  of the apparatus main assembly  38 , by which the development roller  21   a  is directly provided with electric power. Therefore, not only is the end surface  21   a   3  more precisely positioned, but also, it is less exposed, providing thereby a special effect (it is possible to prevent electrically conductive grease adhered to end surface  21   a   3 , from coming into contact with user). The regulating member  19 R is structured so that the regulating portion  19 R 2  surrounds the through hole  19 R 6 . However, the regulating portion  19 R 2  does not extends into the downstream side of the through hole  19 R 6  (part of end surface  21   a   3 ) in terms of the direction in which the yellow development cartridge  5   a  is mounted into the apparatus main assembly  38 , in order to allow the electrical contact  24   a  to smoothly pass, as will be described later in detail. Incidentally, in this embodiment, the direction in which the cartridge  5  is mounted into, or dismounted from, the apparatus main assembly  38  (rotary  1 ), is intersectional (roughly perpendicular) to the rotational axis J (lengthwise direction) of the development roller  21   a.    
         [0076]    Therefore, as the yellow development cartridge  5   a  is mounted into the apparatus main assembly  38 , the electrical contact  24   a  of the apparatus main assembly  38  comes into contact with the end surface  21   a   3  of the development roller  21   a  through the abovementioned through hole  19 R 6 , and retracts in the direction indicated by an arrow mark M in  FIG. 15 . As a result, it becomes possible for the development roller  21   a  to be supplied with voltage. Since the main assembly electrical contact  24   a  is kept pressed upon the end surface  21   a   3  of the development roller  21   a  by a spring  25 , it is ensured that the main assembly electrical contact  24   a  remains in contact with the end surface  21   a   3 . Further, referring to  FIG. 8(   c ), as driving force is transmitted to the yellow development cartridge  5   a  from the apparatus main assembly  38 , the development roller  21   a  comes under the thrust generated in the direction indicated by the arrow mark M in  FIG. 8(   c ) by a helical gear with which the development roller  21   a  is provided. Thus, the end surface  21   a   3  of the development roller  21   a , in terms of the direction parallel to the rotational axis J of the development roller  21   a , comes into contact with the regulating portion  19 R 2 , being thereby controlled in position in terms of its axial direction (lengthwise direction). Therefore, it is possible to keep stable the state of contact between the main assembly electrical contact  24   a  and the end surface  21   a   3  of the development roller  21   a  when the driving force is transmitted from the apparatus main assembly  38  to the yellow development cartridge  5   a . Incidentally, the choice of the structural arrangement for causing the end surface  21   a   3  of the development roller  21   a , in terms of the direction parallel to the axial line J of the development roller  21   a , to come into contact with the regulating portion  19 R 2  does not need to the above described one, which utilizes the thrust generated by the helical gear  27  as the driving force is transmitted to the development roller  21   a . For example, a spring or the like may be used instead. In this embodiment, the supporting member  19 R side, that is, one of the lengthwise end portions of the yellow development cartridge  5   a , is structured, as described above, to ensure that the development roller  21   a  comes into, and remains in contact with, the main assembly electrical contact  24   a ; the supporting member  19 L side, that is, the other lengthwise end portions of the yellow development cartridge  5   a , is not structured to place the development roller  21   a  in contact with the main assembly electrical contact  24   a . Instead, the supporting member  19 L side is provided with the helical gear  28 , and the driving force is transmitted from the helical gear  27  to the helical gear  28  through an idler gear  271 . 
         [0077]    Next, referring to  FIGS. 13 and 15 , the rotary  1  of the apparatus main assembly  38  is provided with four cartridge positioning portions  1   d  for precisely positioning the cartridges  5 , one for one. The four cartridge positioning portions  1   d  are positioned with equal intervals, and next to the four electrical contacts  24   a , one for one. The supporting member  19 R of the yellow development cartridge  5   a  is provided with a supporting portion  19 R 1  for rotatably supporting one of the lengthwise end portions of the development roller  21   a . The supporting portion  19 R 1  extends from the main portion of the supporting member  19 R in the direction parallel to the axial line J (lengthwise direction) of the development roller  21   a . Further, the supporting portion  19 R 1  functions as a positioning portion for precisely positioning the yellow development cartridge  5   a  relative to the apparatus main assembly  38  by engaging with the abovementioned positioning portion  1   d . Thus, as the yellow development cartridge  5   a  is mounted into the rotary  1  of the apparatus main assembly  38 , the peripheral surface of the supporting portion  19 R 1  engages with the inward surface of the positioning portion  1   d . As a result, the yellow development cartridge  5   a  is supported by the rotary  1  in such a manner that the axial line J of the development roller  21   a  of the yellow development cartridge  5   a  coincides with the axial line of the main assembly electrical contact  24   a ; the main assembly electrical contact  24   a  is precisely positioned relative to the axial line J of the development roller  21   a . Further, the contact point of the main assembly electrical contact  24   a  is made semispherical. Therefore, not only is the main assembly electrical contact  24   a  precisely positioned relative to the axial line of the development roller  21   a , but also, the area of contact between the contact point of the main assembly electrical contact  24   a  and the end surface  21   a   3  of the development roller  21   a  is significantly smaller in size than the counterpart in accordance with the prior art, and therefore, the amount by which the end surface  21   a   3  and electrical contact  24   a  are shaved by each other is significantly smaller than the conventional amount. 
         [0078]    Next, referring to  FIGS. 15 and 16 , in order to prevent the problem that the main assembly electrical contact  24   a  and the end surface  21   a   3  are shaved by each other as they rub each other in the area of contact, and also, to ensure that the development roller  21  is reliably supplied with voltage, the end surface  21   a   3  of the development roller  21   a  is coated with electrically conductive grease or the like. Coating the end surface  21   a   3  of the development roller  21   a , which the main assembly electrical contact  24   a  contacts, with electrical conductive grease or the like makes it possible for a user to directly touch the electrical conductive grease, or for the electrically conductive grease to come into direct contact with the objects on a desk when the cartridge  21   a  is placed on the desk. Next, referring to  FIGS. 1 and 15 , in order to prevent these problems, the supporting member  19 R is provided with a protective portion  19 R 3  for protecting the end surface  21   a   3 , which functions as the input electrical contact of the development roller  21   a . The protective portion  19 R 3  extends beyond the end surface  21   a   3  of the development roller  21   a , which is under the regulation from the supporting portion  19 R 1 , in the direction parallel to the axial line J (lengthwise direction) of the development roller  21   a.    
         [0079]    Next, referring to  FIG. 1 , the supporting member  19 R has a passage  19 R 5  for allowing the main assembly electrical contact  24   a  to pass. In terms of the direction in which the yellow development cartridge  5   a  is mounted into the apparatus main assembly  38 , the passage  19 R 5  is on the downstream side of the through hole  19 R 6 . In this embodiment, the passage  19 R 5  is made by removing the downstream side of the protective portion  19 R 3  and supporting portion  19 R 1 . The width W of the passage  19 R 5 , which is shown in  FIG. 17 , is greater than the diameter P of the main assembly electrical contact  24   a , which is shown in  FIG. 14 . The provision of the passage  19 R 5  prevents the protective portion  19 R 3  interfering with the main assembly electrical contact  24   a  when the yellow development cartridge  5   a  is mounted into the apparatus main assembly  38 . The supporting portion  19 R is structured so that as the end surface  21   a   3  (portions other than electrical contact) comes into contact with the regulating portion  19 R 2 , it becomes virtually level with the bottom surface of the passage  19 R 5 . Thus, this structural arrangement makes it easier to mount the cartridge  5  into, or remove the cartridge  5  from, the apparatus main assembly  38 . Further, this structural arrangement makes it unnecessary to form a slanted surface for guiding the main assembly electrical contact  24   a  to the passage  19 RT, making it possible to reducing the cartridge  5  in size. Incidentally, in this embodiment, when molding the supporting member  19 R, the mold for forming the regulating portion  19 R 2 , and the mold for forming the passage portion  19 R 5 , are placed in contact with each other from the opposite directions from each other, in terms of the abovementioned lengthwise direction. Therefore, it is easier to make the end surface  21   a   3  virtually level with the passage portion  19 R 5 . Further, referring to  FIG. 1(   b ), the cartridge  5  is provided with a support portion  41 , which makes contact with the surface on which it is placed outside the apparatus main assembly  38 . The cartridge  5  is also provided with a handle  40 , which is a top portion of the cartridge  5 . When the cartridge  5  is in the above described state, and is seen from its lengthwise direction, the passage portion  19 R 5  is below the protective portion  19 R 3  (between protective portion  19 R 3  and support portion  41 ). The above described structural arrangement makes it difficult for a user to contact the end surface  21   a   3  through the passage  19 R 5 . 
         [0080]    What was described above is the structural arrangement for providing the development roller  21   a  of the yellow development cartridge  5   a  with the voltage from the apparatus main assembly  38 . The structural arrangement for supplying the toner supply roller  22   a  with voltage is the same as that for supplying the development roller  21   a  with voltage. 
         [0000]    (Method for Connecting Electrical Contacts of Development Cartridge with Electrical Contacts of Image Forming Apparatus Main Assembly When Mounting Development Cartridge into Image Forming Apparatus Main Assembly) 
         [0081]    Next, referring to  FIGS. 1 ,  2 ,  15 , and  18 , how the electrical contacts of the yellow development cartridge  5   a  become connected to the electrical contacts of the apparatus main assembly  38  will be described. 
         [0082]      FIG. 18  is an enlarged schematic sectional view of the essential portions of the yellow development cartridge  21   a , as seen from the direction (direction indicated by arrow mark N in  FIG. 13 ) perpendicular to the direction from which the yellow development cartridge  5   a  is mounted, prior to the mounting of the yellow development cartridge  5   a . The supporting member  19 R of the yellow development cartridge  5   a  has a guiding portion  19 R 4  for guiding the main assembly electrical contact  24   a  of the apparatus main assembly  38  to the passage  19 R 5  (end surface  21   a   3  of development roller  21   a ) when the development cartridge  5   a  is mounted into the apparatus main assembly  38 . The guiding portion  19 R 4  is provided next to the passage  19 R 5 , on the downstream side in terms of the cartridge mounting direction (indicated by arrow mark K in  FIG. 18 ). The guiding portion  19 R 4  is a slanted surface, the upstream end of which is lower than its downstream end. 
         [0083]    Next, referring to  FIG. 15 , when the main assembly electrical contact  24   a  of the apparatus main assembly  38  becomes connected to the end surface  21   a   3  of the development roller  21   a , it compresses the spring  25  in the direction indicated by the arrow mark M by a distance t1. That is, before the main assembly electrical contact  24   a  comes into contact with the end surface  21   a   3  of the development roller  21   a  when the development cartridge  5   a  is mounted, the main assembly electrical contact  24   a  and supporting portion  19 R 1  overlap with each other in terms of the cartridge mounting direction (they are located so that they interfere with each other). 
         [0084]    Thus, in order to allow the main assembly electrical contact  24   a  of the apparatus main assembly  38  to smoothly enter the through hole  19 R 6  through the passage  19 R 5 , the supporting member  19 R is provided with the guiding portion  19 R 4  ( FIG. 2(   a )), which is on the downstream side of the supporting portion  19 R 1  of the supporting member  19 R. Thus, while the yellow development cartridge  5   a  is mounted into the rotary  1  of the apparatus main assembly  38 , the main assembly electrical contact  24   a  comes into contact with the guiding portion  19 R 4  as shown in  FIG. 2(   b ). Then, as the yellow development cartridge  5   a  is advanced in the direction indicated by an arrow mark K in  FIG. 3(   a ), the main assembly electrical contact  24   a  is guided by the guiding portion  19 R 4 , being thereby made to gradually retract in the direction indicated by the arrow mark M in  FIG. 3(   a ). Then, the main assembly electrical contact  24   a  enters the through hole  19 R 6  through the passage  19 R 5 , being thereby guided to the end surface  21   a   3  of the development roller  21   a , and comes into contact with the end surface  21   a   3 . Therefore, the yellow development cartridge  5   a  is smoothly mountable in the apparatus main assembly  38 , making it possible to reliably supply the development roller  21   a  with the voltage, without reducing the image forming apparatus in usability. 
         [0085]    As described above, in this embodiment, the image forming apparatus is structured so that the end surface of one of the lengthwise ends of the development roller  21  in terms of the axial direction of the development roller  21  makes direction contact with the electrical contact of the apparatus main assembly  38 . The employment of this structural arrangement can reduce, in count and cost, the components involved in the electrical connection between the apparatus main assembly  38  and development cartridge  5 , and simplify in structure the components, without interfering with the reliability with which voltage is supplied from the apparatus main assembly  38  to the development cartridge  5 . 
         [0086]    Further, the supporting member  19 R is provided with the protective portion  19 R 3  which extends from the main portion of the supporting member  19 R in the abovementioned lengthwise direction of the development roller  21 , beyond the end surface  21   a   3  of the development roller  21   a , to protect the end surface  213 . Thus, such a problem that a user touches the electrically conductive grease coated on the end surface  21   a   3  of the development roller  21  is prevented. Further, the supporting member  19 R is provided with the passage  19 R 5 , which is on the downstream side, in terms of the direction in which the development cartridge  5  is mounted into the apparatus main assembly, to allow the main assembly electrical contact  24   a  of the apparatus main assembly  38  to pass. Therefore, the protective portion  19 R 3  is prevented from interfering with the main assembly electrical contact  24   a  when the development cartridge  5  is mounted into the apparatus main assembly. In terms of the abovementioned lengthwise direction, at least a part of the protective portion  19 R 3  overlaps with at least a part of the regulating portion  19 R 2 . Further, in terms of the lengthwise direction, the passage  19 R 5  is on the inward side of the protective portion  19 R 3 . Moreover, the supporting portion  19 R 1  is structured so that after the proper mounting of the development cartridge  5 , the bottom surface of the passage  19 R 5  is level with the end surface  21   a   3 . 
         [0087]    Further, the supporting member  19 R has the supporting portion  19 R 1 , as an engaging portion, which engages with the positioning portion  1   d , which is located in the adjacency of the main assembly electrical contact  24   a  of the apparatus main assembly  38 , with the presence of a preset amount of distance from the main assembly electrical contact  24   a . Therefore, as the development cartridge  5  is mounted into the rotary  1  of the apparatus main assembly  38 , the peripheral surface of the supporting portion  19 R 1  engages with the inward circumferential surface of the positioning portion  1   d . As a result, the rotary  1  supports the development cartridge  5  so that the axial line of the development roller  21  of the development cartridge  5  coincides with the axial line of the main assembly electrical contact  24   a . That is, the supporting portion  19 R 1  is virtually cylindrical. Therefore, the main assembly electrical contact  24   a  of the apparatus main assembly  38  is precisely positioned on the rotational axis J of the development roller  21 . 
         [0088]    Further, the supporting member  19 R has the guiding portion  19 R 4  which is on the downstream side of the through hole  19 R 6  in terms of the direction in which the development cartridge is mounted into the apparatus main assembly  38 , and which guides the main assembly electrical contact  24   a  to the end surface  21   a   3  (one of end surfaces) of the development roller  21   a  in terms of the axial direction, when mounting the development cartridge into the apparatus main assembly. Therefore, when the development cartridge is mounted into the apparatus main assembly  38 , the main assembly electrical contact  24   a  is guided to the end surface  21   a   3  of the development roller  21   a  along the guiding portion  19 R 4 . Therefore, the development cartridge  5   a  is smoothly mountable into the apparatus main assembly  38 , making it possible to reliably supply the development roller  21   a  with the voltage, without reducing in usability the image forming apparatus and the development cartridge therefor. 
         [0089]    Here, this embodiment has been described with reference to the relationship between the development roller and the electrical contact on the apparatus main assembly. However, the structural arrangement for providing the toner supply roller for supplying the development roller with toner, with the voltage is the same as that for providing the development roller with voltage. Thus, the same effects as the effects described above regarding the development roller, can be obtained for the toner supply roller. Therefore, this embodiment can further simplify the development cartridge in structure and cost by reducing the component count. 
       Embodiment 2 
       [0090]    Next, referring to  FIGS. 19-23 , the process cartridge removably mountable in the main assembly of an electrophotographic image forming apparatus will be described. The structural arrangement, in the second preferred embodiment, for supplying the process cartridge with electric power is roughly the same as that in the first preferred embodiment. Thus, the components, portions, etc., of the image forming apparatus in the second embodiment, which are the same in description, will be given the same referential codes as those given to their counterparts in the first embodiment, and will not be described here. 
       (Description of Process Cartridge) 
       [0091]    First, referring to  FIGS. 5-7 , and  19 - 20 , a process cartridge  39  will be described.  FIG. 19  is a sectional view of the process cartridge  39 .  FIG. 20(   a ) is a perspective view of the charge roller, and  FIG. 20(   b ) is a perspective view of the process cartridge, shows the structural arrangement for supporting the rollers of the process cartridge. 
         [0092]    The process cartridge  39  is a process cartridge made by integrally placing the photosensitive drum  2 , and process means, more specifically, the charging means  3  and cleaning means  6  for processing the photosensitive drum  2 , in a cartridge. It is removably mountable in the apparatus main assembly  38 . The charging mean  3  uniformly charges the photosensitive drum  2  prior to the formation of a latent image. The cleaning means  6  removes the toner particles remaining on the photosensitive drum  2  after the transfer of a toner image from the photosensitive drum  2 . It stores the removed toner particles in the cleaning means container  29 . 
         [0093]    First, the structure of the charging means  3  will be described. The charging means  3  in this embodiment is in the form of a roller. Thus, the charging means  3  will be referred to as a charge roller  3  hereafter. The charge roller  3  is for charging the photosensitive drum  2 . Referring to  FIG. 20(   a ), the charge roller  3  is made up of a rubber roller  3   a  and a shaft  3   b . The shaft  3   b  is put through the rubber roller  3   a  in the direction parallel to the rotational axis of the charge roller  2 . The lengthwise ends of the shaft  3   b  extend from the lengthwise ends of the rubber roller  3   a , one for one, and will be referred to as end portions  3   b L and  3   b R, respectively, hereafter. Next, referring to  FIG. 20(   b ), the charge roller  3  is rotatably supported by a pair of supporting members  30 L and  30 R; the end portions  3   b L and  3   b R are rotatably supported by the supporting members  30 L and  30 R, respectively. The charge roller  3  is supplied with the voltage for charging the photosensitive drum  2 , by the apparatus main assembly  38 . 
         [0000]    (Method for Mounting Process Cartridge into Main Assembly of Image Forming Apparatus, and Method for Removing Process Cartridge from Main Assembly of Image Forming Apparatus) 
         [0094]    Next, referring to  FIG. 21 , the operation for mounting the process cartridge  39  into the apparatus main assembly  38 , and the operation for dismounting the process cartridge  39  from the apparatus main assembly  38 , will be described. 
         [0095]    Referring to  FIG. 21 , first, a cover  31  is to be opened. As the cover  31  is opened, it becomes possible for the process cartridge  39  to be dismounted from, or mounted into, the apparatus main assembly  38  in the directions indicated by arrow marks N and O, respectively. The direction indicated by the arrow mark N is the direction in which the process cartridge  39  is to be dismounted, and the direction indicated by the arrow mark O is the direction in which the process cartridge  39  is to be mounted. 
         [0000]    (Description of Structural Arrangement for Supplying Charge Roller with Voltage from Main Assembly of Image Forming Apparatus) 
         [0096]    Next, referring to  FIGS. 22-24(   a ), the structural arrangement for supplying the charge roller  3  of the process cartridge  39  with the voltage from the main assembly  38  of the image forming apparatus will be described. 
         [0097]      FIG. 22  is an enlarged sectional view of the main assembly electrical contacts, as seen from the direction in which the process cartridge  39  is mounted, prior to the mounting of the process cartridge  39 .  FIGS. 22(   b ) and  22 ( c ) are enlarged sectional views of the main assembly electrical contact, and the essential portions of the process cartridge  39 , when the process cartridge  39  is in the apparatus main assembly  38 .  FIG. 23  is a perspective view of one of the charge roller supporting members of the process cartridge  39 .  FIG. 24(   a ) is an enlarged sectional view of the one of the end portions of the charge roller  3  of the process cartridge  39 , as seen from the direction in which the process cartridge  39  is mounted into the apparatus main assembly  38 . 
         [0098]    Referring to  FIG. 22 , the apparatus main assembly  38  is provided with an electrical contact  32  for supplying the charge roller  3  with voltage. This electrical contact  32  is positioned so that when the process cartridge  39  is in its image forming position in the apparatus main assembly  38 , it will be on the rotational axis Q of the charge roller  3 . 
         [0099]    Also referring to  FIG. 22 , the right side plate  33 R of the main assembly  38  of the image forming apparatus is provided with an electrical contact engagement hole  33 Ra in which the main assembly electrical contact  32  engages, and a regulating wall  33 Rb for preventing the main assembly electrical contact  32  from popping out of the side plate  33 R in the direction indicated by an arrow mark S in  FIG. 22 . The main assembly electrical contact  32  is held to the side plate  33 R by a spring  34 , which is for keeping the electrical contact  32  pressed in the direction indicated by an arrow mark S in  FIG. 22 , and a spring cover  35 , while being allowed to move, relative to the side plate  33 R, in the direction parallel to the rotational axis Q of the charge roller  3 . Further, the electrical contact  32  is provided with a flange portion  32   a  for preventing the accident that as the electrical contact  32  is pressed against the regulating wall  33 Rb of the side plate  33 R, it pops out of the side plate  33 R in the direction indicated by the arrow mark S in  FIG. 22 . Thus, the electrical contact  32  is prevented from popping out of the side plate  33 R in the direction indicated by the arrow mark S in  FIG. 22 , when the process cartridge  39  is not in the apparatus main assembly  38 . 
         [0100]    Referring to  FIG. 22(   b ), on the other hand, the supporting member  30 R of the process cartridge  39  is provided with a regulating portion  30 R 2  for regulating the movement of the charge roller  3  in the direction parallel to the rotational axis Q of the charge roller  3 . This regulating portion  30 R 2  is the positioning portion for precisely positioning the lengthwise end surface  3   c  of the charge roller  3 ; as the lengthwise end surface  3   c  of the charge roller  3  comes into contact with the regulating portion  30 R 2 , the lengthwise end surface  3   c  becomes precisely positioned. The regulating portion  30 R 2  is provided with a through hole  30 R 6 , through which the lengthwise end surface  3   c  of the charge roller is allowed to directly contact the aforementioned electrical contact  32  of the apparatus main assembly  38 . The structures and functions of the through holes  30 R 6  and regulating portion  30 R 2 , and the direction in which the process cartridge  39  is mounted into, or dismounted from, the apparatus main assembly  38 , are the same as those in the first preferred embodiment. 
         [0101]    Thus, as the process cartridge  39  is mounted into the apparatus main assembly  38 , the main assembly electrical contact  32  comes into contact with the end surface  3   c  of the charge roller  3  through the through hole  30 R 6 , being thereby enabled to supply the charge roller  3  with voltage, and retracts in the direction indicated by an arrow mark U in  FIG. 22(   b ). The main assembly electrical contact  32  is under the pressure applied to the end surface  3   c  of the charge roller  3  by the spring  34 , being ensured to remain in contact with the end surface  3   c . Next, referring to  FIG. 22(   c ), as driving force is transmitted to the process cartridge  39  from the apparatus main assembly  38 , the end surface  3   c  of the charge roller  3 , that is, one of the end surfaces of the charge roller  3  in terms of the direction parallel to the axial line Q of the charge roller  3 , is subjected to a force directed as indicated by an arrow mark U in  FIG. 22  ( c ). Thus, the end surface  3   c  of the charge roller  3  in terms of the direction parallel to the axial line Q of the charge roller  3  comes into contact with the regulating portion  30 R 2 , being thereby precisely positioned in terms of its axial direction (lengthwise direction). Therefore, it is possible to reliably keep the main assembly electrical contact  32  in contact with the end surface  3   c  of the charge roller  3  when the driving force is transmitted to the process cartridge  39  from the apparatus main assembly  38 . Next, referring to  FIG. 29 , as for the structural arrangement for subjecting the charge roller  3  to the force, the direction of which is indicated by the arrow mark U in  FIG. 22(   c ), the charge roller  3  is supported by the supporting members  30 L and  30 R in such a manner that the rotational axis W of the charge roller  3  intersects with the rotational axis Y of the photosensitive drum  2  at an angle of Z. Thus, as the photosensitive drum  2  is rotated in the direction indicated by an arrow mark C in  FIG. 21 , the charge roller  3  is subjected to the force from the photosensitive drum  2 , the direction of which is indicated by the arrow mark U in  FIG. 22(   c ). Incidentally, the structural arrangement for causing the end surface  3   c  of the charge roller  3  in terms of the direction parallel to the axial line Q of the charge roller  3 , to come into contact with the regulating portion  30 R 2 , may be replaced with a pair of helical gears or a spring designed to thrust the charge roller  3  in the direction indicated by the arrow mark U in  FIG. 22(   c ). 
         [0102]    Further, the side plate  33 R of the apparatus main assembly  38  is provided with four positioning portions (unshown), one for each of the four main assembly electrical contacts  32  (unshown). Each positioning portion is in the adjacency of the corresponding main assembly electrical contact  32 , with the presence of a preset amount of distance from the main assembly electrical contact  32 . These positioning portions are the same in structure as those in the first preferred embodiment. Further, the supporting member  30 R of the process cartridge  39  is provided with a supporting portion  30 R 1 , which rotatably supports one of the lengthwise ends of the charge roller  3 . The supporting portion  30 R 1  of the supporting member  30 R extends from the main portion of the supporting member  30 R in the direction (lengthwise direction) parallel to the axial line Q of the charge roller  3 . Further, the supporting portion  30 R 1  functions as a positioning portion for precisely positioning the process cartridge  39  relative to the apparatus main assembly  38  by engaging with the abovementioned positioning portion (unshown) of the apparatus main assembly  38 . Thus, as the process cartridge  39  is mounted into the apparatus main assembly  38 , the abovementioned supporting portion  30 R 1  engages with the positioning portion (unshown). As a result, the process cartridge  39  is supported by the apparatus main assembly  38  in such a manner that the axial line Q of the charge roller  3  of the process cartridge  39  coincides with the axial line of the main assembly electrical contact  32 ; the main assembly electrical contact  32  is precisely positioned relative to the axial line Q of the charge roller  3 . Further, the contact point portion of the main assembly electrical contact  32  is made semispherical. Thus, not only is the main assembly electrical contact  32  precisely positioned relative to the axial line Q of the charge roller  3 , but also, the area of contact between the contact point of the main assembly electrical contact  32  and the end surface  3   c  of the charge roller  3  is significantly smaller is size than the counterpart in accordance with the prior art, and therefore, the amount by which the end surface  3   c  and main assembly electrical contact  32  are shaved by each other is significantly smaller than the conventional amount. 
         [0103]    Next, referring to  FIGS. 15 and 16 , in order to prevent the problem that the main assembly electrical contact  32  and the end surface  3   c  are shaved by each other as they rub against each other in the area of contact, and also, to ensure that the charge roller  3  is reliably supplied with voltage, the end surface  3   c  of the charge roller  3  is coated with electrically conductive grease or the like. Coating the end surface  3   c  of the charge roller  3 , which the main assembly electrical contact  32  contacts, with electrical conductive grease or the like makes it possible for a user to directly touch the electrical conductive grease, or for the electrically conductive grease to come into direct contact with the objects on a desk when the cartridge  21   a  is placed on the desk. Thus, in order to prevent these problems, the supporting member  30 R is provided with a protective portion  30 R 3  (protrusive portion) for protecting the end surface  3   c , which functions as the input electrical contact of the charge roller  3 , as shown in  FIGS. 22(   c ) and  23 . The protective portion  30 R 3  extends beyond the end surface  3   c  of the charge roller  3 , which is under the regulation from the regulating portion  30 R 2  in the direction parallel to the axial line Q (lengthwise direction) of the charge roller  3 . 
         [0104]    Next, referring to  FIG. 23 , the supporting member  30 R 3  and supporting portion  30 R 1  are provided with a passage  30 R 5  for allowing the main assembly electrical contact  32  to pass. In terms of the direction in which the process cartridge  39  is mounted into the apparatus main assembly  38 , the passage  30 R 5  is on the downstream side of the through hole  30 R 6 . The width V of the passage  30 R 5 , which is shown in  FIG. 24(   a ), is greater than the diameter T of the main assembly electrical contact  32 , which is shown in  FIG. 22 . The provision of the passage  30 R 5  prevents the protective portion  30 R 3  interfering with the main assembly electrical contact  32  when the process cartridge  39  is mounted into the apparatus main assembly  38 . The structures and functions of the protective portion  30 R 3  and passage  30 R 5  are the same as the counterparts in the first preferred embodiment. 
         [0000]    (Method for Connecting Electrical Contacts of Process Cartridge with Electrical Contacts of Image Forming Apparatus Main Assembly When Mounting Process Cartridge into Image Forming Apparatus Main Assembly) 
         [0105]    Next, referring to  FIGS. 23 ,  24 ( b ), and  24 ( c ), how the electrical contact of the process cartridge  39  becomes connected with the main assembly electrical contact  32  when the process cartridge  39  is mounted into the apparatus main assembly  38  will be described. 
         [0106]      FIG. 24(   b ) is an enlarged schematic sectional view of the essential portions of the process cartridge  39 , as seen from the direction (direction indicated by arrow mark X in  FIG. 23)  perpendicular to the direction from which the process cartridge  39  is mounted, prior to the mounting of the process cartridge  39 . The supporting member  30 R of the process cartridge  39  has a guiding portion  30 R 4  for guiding the main assembly electrical contact  32  of the apparatus main assembly  38  to the end surface  3   c  of the charge roller  3  when the process cartridge  39  is mounted into the apparatus main assembly  38 . The guiding portion  30 R 4  is provided on the downstream side of the through hole  30 R 6  in terms of the direction in which the process cartridge is mounted into the apparatus main assembly  38  (indicated by arrow mark O in  FIG. 23 ). The guiding portion  30 R 4  is a slanted surface, the upstream end of which is lower than its downstream end. 
         [0107]    Next, referring to  FIG. 22(   b ), as the main assembly electrical contact  32  becomes connected to the end surface  3   c  of the charge roller  3 , it compresses the spring  34  in the direction indicated by the arrow mark U by a distance t 2 . That is, before the main assembly electrical contact  32  comes into contact with the end surface  3   c  of the charge roller  3  when the process cartridge  39  is mounted, the main assembly electrical contact  32  and supporting portion  30 R 1  overlap with each other in terms of the cartridge mounting direction (they are located so that they interfere with each other). 
         [0108]    Thus, in order to allow the main assembly electrical contact  32  to smoothly enter the through hole  30 R 6  through the passage  30 R 5 , the supporting member  30 R is provided with the guiding portion  30 R 4 , which is on the downstream side of the supporting portion  30 R 1  of the supporting member  30 R in terms of the cartridge mounting direction. Thus, while the process cartridge  39  is mounted into the apparatus main assembly  38 , the main assembly electrical contact  32  comes into contact with the guiding portion  30 R 4 . Then, as the process cartridge  39  is advanced further in the direction indicated by an arrow mark O in  FIG. 23 , the main assembly electrical contact  32  is guided by the guiding portion  30 R 4 , being thereby made to gradually retract in the direction indicated by the arrow mark U in  FIG. 24(   c ). Then, the main assembly electrical contact  32  enters the through hole  30 R 6  by way of the passage  30 R 5 , being thereby guided to the end surface  3   c  of the charge roller  3 , and comes into contact with the end surface  3   c . Therefore, the process cartridge  39  is smoothly mountable in the apparatus main assembly  38 , making it possible to reliably supply the charge roller  3  with voltage, without reducing the image forming apparatus in usability. The structure and function of this guiding portion  30 R 4  are the same as those of the guiding portion  19 R 4  in the first preferred embodiment. 
         [0109]    As described above, in this embodiment, the image forming apparatus is structured so that the end surface of one of the lengthwise ends of the charge roller  3  in terms of the axial direction of the charge roller  3  makes direction contact with the main assembly electrical contact  32 . The employment of this structural arrangement can reduce, in count and cost, the components involved in the electrical connection between the main assembly of an image forming apparatus and a process cartridge, and can simplify an image forming apparatus in structure, without interfering with the reliability with which voltage is supplied from the apparatus main assembly to the process cartridge. 
         [0110]    Further, the supporting member  30 R is provided with the protective portion  30 R 3  which extends from the main portion of the supporting member  30 R in the abovementioned lengthwise direction of the charge roller  3 , beyond the end surface  3   c  of the charge roller  3 , to protect the end surface  3   c . Thus, such a problem that a user touches the electrically conductive grease coated on the end surface  3   c  of the charge roller  3  is prevented. Further, the supporting member  30 R is provided with the passage  30 R 5 , which is on the downstream side, in terms of the direction in which the process cartridge  39  is mounted into the apparatus main assembly  38 , to allow the main assembly electrical contact  32  of the apparatus main assembly  38  to pass. Therefore, the protective portion  30 R 3  is prevented from interfering with the main assembly electrical contact  32  when the process cartridge  39  is mounted into the apparatus main assembly  38 . 
         [0111]    Further, the supporting member  30 R has the supporting portion  30 R 1 , as an engaging portion, which engages with the positioning portion (unshown), with which the apparatus main assembly  38  is provided. Therefore, as the process cartridge  39  is mounted into the apparatus main assembly  38 , the supporting portion  30 R 1  engages with the abovementioned positioning portion (unshown). As a result, the main assembly electrical contact  32  is precisely positioned on the axial line of the charge roller  3 . 
         [0112]    Further, the supporting member  30 R has the guiding portion  30 R 4  which is on the downstream side of the through hole  30 R 6  in terms of the direction in which the process cartridge  39  is mounted into the apparatus main assembly  38 , and which guides the main assembly electrical contact  32  to the end surface  3   c  (one of end surfaces) of the charge roller in terms of the axial direction, when the process cartridge  39  is mounted into the apparatus main assembly. Therefore, when the process cartridge  39  is mounted into the apparatus main assembly  38 , the main assembly electrical contact  32  is guided to the end surface  3   c  of the charge roller  3  along the guiding portion  30 R 4 . Therefore, the process cartridge  39  is smoothly mountable into the apparatus main assembly  38 , making it possible to reliably supply the charge roller  3  with voltage, without reducing in usability the image forming apparatus and the development cartridge therefor. 
       Miscellaneous Embodiments 
       [0113]    In the preceding preferred embodiments of the present invention, the process cartridge  39 , which has the photosensitive drum  2  and charge roller  3 , was independent from the development cartridge  5 , which has the development roller  21 . However, these embodiments are not intended to limit the present invention in terms of process cartridge type. For example, the present invention is also compatible with a process cartridge made up by integrating the process cartridge  39  and development cartridge  5 . In the case of integrating the process cartridge  39  and development cartridge  5 , they should be integrated so that the development roller supporting member and charge roller supporting member of the resulting process cartridge will be the same in structure, because such an integration can offer the same effects as those described above regarding the preceding embodiments, that is, it can further reduce in component count the resulting process cartridge, and therefore, can simplify in structure, and can reduce in cost, the resulting process cartridge. 
         [0114]    Also in the second preferred embodiment, the process cartridge was removably mountable in the main assembly of the image forming apparatus, and had a photosensitive drum and a charge roller. However, the second embodiment is not intended to limit the application of the present invention to a process cartridge of the above described type. That is, the present invention is compatible with any process cartridge having at least an electrophotographic photosensitive member and one or more processing means for processing the photosensitive member. By structuring the main assembly of an electrophotographic image forming apparatus and a process cartridge therefor so that the roller (or rollers), which the process cartridge has, directly contacts the electrical contact (contacts), which the main assembly of the apparatus has, it is possible to reduce the image forming apparatus and process cartridge therefor in component count, simplify them in structure, and reduce them in cost. 
         [0115]    Further, in the first preferred embodiment, the image forming apparatus used four development cartridges. However, the first embodiment is not intended to limit the present invention in terms of the development cartridge count. That is, the present invention is applicably to any electrophotographic image forming apparatus regardless of the development cartridge count. Further, the present invention is applicable to any electrophotographic image forming apparatus regardless of the process cartridge count. 
         [0116]    Further, in the preceding preferred embodiments, the electrophotographic image forming apparatuses were printers. However, the preceding embodiments are not intended to limit the application of the present invention to a printer. That is, not only is the present invention applicable to a printer, but also, other image forming apparatuses, such as a facsimile apparatus. Further, the present invention is applicable to a multifunction apparatus, that is, an apparatus made up of a printer, a facsimile, etc., and capable of functioning as various image forming apparatuses. 
         [0117]    The application of the present invention is not limited to an image forming apparatus, which has an intermediary transfer member, transfers in layers toner images, different in color, onto the intermediary transfer member, and transfers all at once the toner images on the intermediary transfer member, onto recording medium. The present invention is also applicable to an image forming apparatus, which has a recording medium bearing member, and sequentially transfers in layers, toner images, different in color, onto the recording medium on the recording medium bearing member. 
         [0118]    That is, the application of the present invention to the cartridge, which is removably mountable in any of the abovementioned electrophotographic image forming apparatuses can provide the same effects as those achieved by the image forming apparatuses in the preceding preferred embodiments. 
         [0119]    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. 
         [0120]    This application claims priority from Japanese Patent Applications Nos. 223043/2008 and 160763/2009 filed Sep. 1, 2008 and Jul. 7, 2009, respectively, which are hereby incorporated by reference.