Abstract:
An image forming apparatus includes a cartridge including an electrophotographic photosensitive member, a developing roller, a spacer movable between spacing and contacting positions for spacing apart and contacting the roller and member, and a receiver receiving a force spacing the roller from the member. The apparatus includes a mounter detachably mounting the cartridge, an abuter retracting the spacer from the spaced position when the mounter mounts the cartridge with the spacer at the spaced position, and a function member movable between a first position spacing the roller from the member by abutting the receiver with the cartridge mounted to the mounter and a second position contacting the roller to the member. When the mounter mounts the cartridge with the spacer at the spaced position, the abuter abuts the spacer retracting it from the spaced position after insertion so that the function member taking the first position abuts the receiver.

Description:
FIELD OF THE INVENTION AND RELATED ART 
       [0001]    The present invention is related to a process cartridge, and an image forming apparatus which employs a process cartridge. 
         [0002]    Here, an electrophotographic image forming apparatus is an apparatus which forms an image on recording medium with the use of an electrophotographic image forming apparatus. As examples of an electrophotographic image forming apparatus, there are an electrophotographic copying machine, an electrophotographic printer (for example, laser beam printer, LED printer, etc.), a facsimile machine, a wordprocessor, etc. 
         [0003]    A process cartridge is a cartridge in which at least a developing means and an electrophotographic photosensitive drum are integrally disposed. Some process cartridges are removably mountable in the main assembly of an electrophotographic image forming apparatus. 
         [0004]    Further, some electrophotographic color image forming apparatuses in accordance with the prior art employ multiple process cartridges, which are arranged side by side in parallel in a straight row (which henceforth is referred to as inline type) in the main assembly of the image forming apparatus. As one of the methods used by a developing means in a process cartridge, a developing method of the so-called contact type has been known, according to which a latent image on the photosensitive member in a process cartridge is developed with the development roller placed in contact with the photosensitive drum. In the case of a process cartridge employing this developing method, the development roller is kept pressured toward the photosensitive drum, in order to keep the development roller in contact with the photosensitive drum, and maintain a preset amount of pressure between the development roller and photosensitive drum. 
         [0005]    Generally, a development roller used for a developing method of the contact type is provided with an elastic layer. Thus, if a cartridge used for the developing method of the contact type is left unused for a substantial length of time in the main assembly of an image forming apparatus, the portion of the elastic layer, which is in contact with the photosensitive drum, sometimes deforms, which results in the formation of an image which is nonuniform in density or the like. In order to prevent this problem, not only must the materials for a development roller be very strictly selected, but also, the conditions under which a development roller is manufactured must be strictly controlled. In other words, this deformation of the elastic layer of a development roller has been a serious concern with the manufacturing of a development roller. 
         [0006]    Thus, there has been proposed a process cartridge and an image forming apparatus, which are provided with a mechanism for keeping the development roller separated from the photosensitive drum while the image forming apparatus is not used for image formation (Japanese Laid-open Patent Application 2001-337511 (p. 5-p. 6, FIG. 2). 
         [0007]    There has also been proposed a process cartridge and an image forming apparatus, which are structured to keep the development roller separated from the photosensitive drum with the use of a separating member while the process cartridge is not in use (Japanese Laid-open Patent Application 2002-6722). 
         [0008]    Moreover, there has been a process cartridge provided with a member for keeping the development roller separated from the photosensitive member, in the process cartridge during the shipment of the process cartridge (this member hereafter may be referred to simply as separating member). In the case of this process cartridge, as the process cartridge is inserted (mounted) into an image forming apparatus compatible with the process cartridge, the separating member comes into contact with the separating member disengaging portion of the main assembly of the image forming apparatus, and is disengaged by the further insertion of the process cartridge. 
         [0009]    In the case of a process cartridge and an image forming apparatus, which are in accordance with the prior art described above, while the process cartridge is mounted into the image forming apparatus, first, the separating member comes into contact with the separating member disengaging portion of the main assembly of the image forming apparatus, and then, is disengaged by the further insertion of the process cartridge, allowing the development unit to move from the position in which it keeps the development roller separated from the photosensitive drum, to the position in which it keeps the development roller in contact with the photosensitive drum. Further, the development unit is always under the pressure from the pressure applying members. Therefore, as the separating member becomes disengaged, the development roller virtually collides with the photosensitive member, generating thereby a substantial amount of shock, and this shock is transmitted to the user who is mounting the process cartridge. Therefore, the process cartridge and image forming apparatus which are in accordance with the prior art do not offer a feel of smoothness to the user when the user is mounting the process cartridge into the image forming apparatus. 
         [0010]    Also in the case of the process cartridge and image forming apparatus, which are in accordance with the prior art, after the separating member is moved out of the position in which it keeps the development roller separated from the photosensitive drum, the process cartridge must be inserted further in order to finish the operation for mounting the process cartridge. Further, before the end of the operation for mounting the process cartridge, the force bearing portion of the development unit must be moved onto the development roller separating means of the main assembly of the image forming apparatus, in order to move the development unit into the position in which it keeps the development roller separated from the photosensitive drum. 
         [0011]    Therefore, in the case of the above described process cartridge and image forming apparatus, which are in accordance with the prior art, the process cartridge is subjected to two different kinds of load, that is, the load to which it is subjected to disengage the separating member, and the load to which it is subjected at the end of the operation for mounting the process cartridge. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention is one of the results of the further development of the prior art described above, and its primary object is to improve a process cartridge and an image forming apparatus, in terms of the operability regarding the mounting of the process cartridge into the main assembly of the image forming apparatus. 
         [0013]    According to an aspect of the present invention, there is provided an electrophotographic image forming apparatus capable of capable of forming an image on a recording material, comprising a process cartridge including an electrophotographic photosensitive member, a developing roller contactable to said electrophotographic photosensitive member, a spacer member movable between a spacing position for spacing said developing roller from said electrophotographic photosensitive member and a contacting position for contacting said developing roller to said electrophotographic photosensitive member, and a force receiving portion for receiving a force for spacing said developing roller from said electrophotographic photosensitive member; a mounting portion for detachably mounting said process cartridge; an abutting member for retracting said spacer member from the spaced position by abutting said spacer member when said process cartridge is inserted into said mounting portion with said spacer member at the spaced position; a function member movable between a first position for spacing said developing roller from said electrophotographic photosensitive member by abutting to said force receiving portion with said process cartridge mounted to said mounting portion and a second position for contacting said developing roller to said electrophotographic photosensitive member, wherein when said process cartridge is inserted into said mounting portion with said spacer member at the spaced position, said abutting member is abutted to said spacer member to retract said spacer member from said spaced position after said process cartridge is inserted into said mounting portion to such a position where said function member taking the first position is abuttable to said force receiving portion. 
         [0014]    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 
         [0015]      FIG. 1  is a sectional view of the image forming apparatus in the first embodiment of the present invention, showing the overall structure of the apparatus. 
           [0016]      FIG. 2  is a cross-sectional view of the process cartridge in the first embodiment of the present invention. 
           [0017]      FIG. 3  is a cross-sectional view of the process cartridge in which the development roller is in contact with the photosensitive drum. 
           [0018]      FIG. 4  is a cross-sectional view of the process cartridge in which a gap is present between the development roller and the photosensitive drum. 
           [0019]      FIG. 5  is a perspective view of the image forming apparatus in the first embodiment, in which one of the process cartridges is at the entrance of the corresponding cartridge bay in the image forming apparatus, being ready to be mounted into the apparatus. 
           [0020]      FIG. 6  is a cross-sectional view of the image forming apparatus in the first embodiment, in which one of the process cartridges is being inserted into the corresponding cartridge bay in the image forming apparatus, being ready to be mounted into the apparatus. 
           [0021]      FIG. 7  is an external perspective view of the process cartridge, as seen from the downstream side in terms of the direction in which the cartridge is mounted into the main assembly of the image forming apparatus. 
           [0022]      FIG. 8  is a perspective view of the separating member of the process cartridge, which is at the downstream end in terms of the direction in which the process cartridge is mounted into the main assembly of the image forming apparatus. 
           [0023]      FIG. 9  is a side view of the separating member of the process cartridge, which is at the downstream end, in terms of the direction in which the process cartridge is mounted into the main assembly of the image forming apparatus,  FIG. 9(   a ) showing the engaged separating member, and  FIG. 9(   b ) showing the disengaged separating member. 
           [0024]      FIG. 10  is an external perspective view of the process cartridge, as seen from the upstream side, in terms of the direction in which the process cartridge is mounted into the main assembly of the image forming apparatus. 
           [0025]      FIG. 11  is a perspective view of the separating member on the upstream side in terms of the direction in which the process cartridge is mounted into the main assembly of the image forming apparatus. 
           [0026]      FIG. 12  is a side view of the separating member on the upstream side,  FIG. 12(   a ) showing the engaged separating member, and  12 ( b ) showing the disengaged separating member. 
           [0027]      FIG. 13  is a front view of one of the process cartridge bays of the image forming apparatus, and the process cartridge which is being mounted into the bay. 
           [0028]      FIG. 14  is a sectional view of one of the process cartridge bays of the image forming apparatus, and the process cartridge which is being mounted into the bay. 
           [0029]      FIG. 15  is a sectional view of one of the process cartridge bays of the image forming apparatus, and the process cartridge which has just been completely mounted into the bay. 
           [0030]      FIG. 16  is a front view of one of the process cartridge bays of the image forming apparatus in the second embodiment of the present invention, and the process cartridge in the second embodiment, which is being mounted into the bay. 
           [0031]      FIG. 17  is a perspective view of one of the process cartridge bays of the main assembly of the image forming apparatus in the second embodiment, as seen from the opening side of the bay. 
           [0032]      FIG. 18  is a sectional view of one of the process cartridge bays of the image forming apparatus in the second embodiment, and the process cartridge in the second embodiment, which is being mounted into the bay. 
           [0033]      FIG. 19  is a sectional view of one of the process cartridge bays of the image forming apparatus in the second embodiment, and the process cartridge in the second embodiment, which is being mounted into the bay. 
           [0034]      FIG. 20  is a sectional view of one of the process cartridge bays of the image forming apparatus in the second embodiment, and the process cartridge in the second embodiment, which has just been completely mounted into the bay. 
           [0035]      FIG. 21  is an external perspective view of the process cartridge, and its protective cover, in the third embodiment of the present invention. 
           [0036]      FIG. 22  is a perspective view of the process cartridge in the third embodiment of the present invention, and the main assembly of the image forming apparatus in the third embodiment, into which the process cartridge is being mounted. 
           [0037]      FIG. 23  is a cross-sectional view of the process cartridge in the third embodiment of the present invention, and the main assembly of the image forming apparatus in the third embodiment, into which the process cartridge is being mounted. 
           [0038]      FIG. 24  is a sectional view of one of the process cartridge bays of the image forming apparatus in the third embodiment, and the process cartridge in the third embodiment, which has just been completely mounted into the bay. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 1 
       [0039]    Next, the process cartridge and image forming apparatus in the first of the preferred embodiments of the present invention will be described with reference to the appended drawings.  FIG. 1  is a sectional view of the image forming apparatus in the first embodiment, showing the overall structure of the apparatus. 
       (Overall Structure of Image Forming Apparatus) 
       [0040]    First, the overall structure of the image forming apparatus will be described. The image forming apparatus  100  shown in  FIG. 1  has four process cartridge bays (unshown).  FIG. 5  is a perspective view of the image forming apparatus in the first embodiment, in which one of the process cartridges is at the entrance of the corresponding cartridge bay in the image forming apparatus, being ready to be mounted into the apparatus. 
         [0041]    Referring to  FIG. 5 , the process cartridges  7  ( 7   a - 7   d ) are removably mountable in the process cartridge bays  90  of the main assembly of the image forming apparatus  100 , respectively. In order to mount the cartridge  7  in the image forming apparatus  100 , first, the front cover  8  with which the main assembly of the image forming apparatus  100  is provided must be opened, and then, the process cartridge  7  must be inserted into the main assembly in the preset direction (indicated by arrow mark E). That is, the process cartridge  7  is structured so that it can be removably mountable in the process cartridge bay  90 . Each cartridge  7  has a photosensitive member unit  26  ( 26   a - 26   d ), and a development unit  4  ( 4   a - 4   d ) (second unit). The development unit  4  has a development roller  40 . The photosensitive member unit  26  has a charge roller  2  ( 2   a - 2   d ), a cleaning member  6  ( 6   a - 6   d ), and a photosensitive drum  1  ( 1   a - 1   d ) as an electrophotographic photosensitive member. 
         [0042]    The image forming operation of the image forming apparatus is as follows: Each photosensitive member is rotated, it is uniformly charged by the charge roller  2 . Then, the numerous points of the uniformly charged peripheral surface of the photosensitive drum  1  are selectively exposed by a scanner unit  3 . As a result, an electrostatic latent image is formed on the photosensitive drum  1 . Then, the electrostatic latent image is developed by the development roller  40  as a developing member. As a result, four visible images, different in color, are formed on the photosensitive drums, one for one; four images are formed of developer (toner), different in color, on the photosensitive drums, one for one. 
         [0043]    Meanwhile, recording sheets S in a cassette  17  in the bottom portion of the main assembly of the image forming apparatus  100  are sent one by one by a feed roller  18 , and a pair of conveyance roller  19 , to the nip formed by a transfer belt  11  and a secondly transfer roller  15 . In this nip, the four toner images, different in color, on the transfer belt  11  are transferred onto the recording sheet S. 
         [0044]    After the transfer of the toner images, the recording sheet S is subjected to heat and pressure in a fixing portion  20 . As a result, the toner images are fixed. Thereafter, the recording sheet S is discharged from the image forming apparatus  100  by a pair of discharge rollers  23 . 
       (Process Cartridge) 
       [0045]    Next, the process cartridges  7  will be described.  FIG. 2  is a cross-sectional view of the cartridge  7  in which developer (toner) is stored. In this embodiment, the cartridges  7   a - 7   d  are the same in structure. The cartridge  7   a - 7   d  store yellow, magenta, cyan, and black toners, respectively. 
         [0046]    Referring to  FIG. 2 , the cartridges  7  ( 7   a - 7   d ) are made up of the photosensitive member unit  26  ( 26   a - 26   d ) (first unit), and the development unit  4  ( 4   a - 4   d ), which are in connection to each other. 
         [0047]    The photosensitive member units  26  ( 26   a - 26   d ) have the photosensitive drums  1  ( 1   a - 1   d ), charge rollers  2  ( 2   a - 2   d ), cleaning members  6  ( 6   a - 6   d ), and cleaning means frames  27  ( 27   a - 27   d ), respectively. The photosensitive drum  1  is rotatably supported by the cleaning means frame  27 . The charge roller  2  and cleaning member are in the adjacencies of the peripheral surface of the photosensitive drum  1 . The residual toner on the peripheral surface of the photosensitive drum  1  is removed by the cleaning member  6 . As it is removed, it falls into a chamber  27   a  for the removed residual toner. The charge roller  2  is kept pressed toward the photosensitive drum  1 . 
         [0048]    The development roller  40  is supported by the development unit  4 , and rotates in contact with the photosensitive drum  1 , in the direction indicated by an arrow mark B. The development unit  4  is connected to the photosensitive member unit  26  with the use of a pair of connective pins  37 , being thereby enabled to rotationally move (pivotally move) relative to the photosensitive member unit  26 , about the pair of pins  37 . 
         [0049]    The development unit  4  can be pivotally moved into a position in which it keeps the development roller  40  in contact with the photosensitive drum  1 , and a position in which it keeps a preset amount of distance between the development roller  40  and photosensitive drum  1 . The development unit  4  is under the pressure applied by compression springs  53  (pressure applying members) in the direction to make the development unit  4  pivot into the abovementioned position in which it keeps the development roller  40  in contact with the photosensitive drum  1 . Therefore, as the cartridge  7  begins to be used for an image forming operation, the development unit  4  rotates about the pair of connective pins  37 , causing thereby the development roller  40  to come into contact with the photosensitive drum  1 , because the development unit  4  is always under the abovementioned pressure. 
       (Mechanism for Keeping Development Roller  40  Separated from Photosensitive Drum When Process Cartridge  7  is in Apparatus Main Assembly) 
       [0050]    Next, the mechanism for keeping the development roller  40  separated from the photosensitive drum  1  after the completion of the operation for mounting the process cartridge  7  will be described.  FIG. 3  is a cross-sectional view of the cartridge  7  which is in the cartridge bay  90  of the image forming apparatus, and a separation cam  111  with which the main assembly of the image forming apparatus  100  (which hereafter may be referred to simply as apparatus main assembly  100 ) is provided. When the cartridge  7  is in the state shown in  FIG. 3 , the development roller  40  is in contact with the photosensitive drum  1 .  FIG. 4  is also a cross-sectional view of the cartridge  7 , and the separation cam  111  of the apparatus main assembly  100 , when the cartridge  7  is in the cartridge bay  90  of the apparatus main assembly  100 . When the cartridge  7  and separation cam  111  is in the state shown in  FIG. 4 , there is a gap between the development roller  40  and photosensitive drum  1 . 
         [0051]    The apparatus main assembly  100  is provided with the separation cam  111  as a rotatable member, the position of which corresponds to the lengthwise center portion of the cartridge  7 . The separation cam  111  is a means for causing the development roller  40  to separate from the photosensitive drum  1  against the pressure from the compression springs  53 . The separation cam  111  is solidly attached to its shaft  80 . Therefore, it rotates as the shaft  80  rotates. The separation cam  111  has a small radius portion  111   b  and a large radius portion  111   c.    
         [0052]    Referring to  FIG. 3 , the radius of the small radius portion  111   b  is such that when the development roller  40  is in contact with the photosensitive drum  1 , a gap T is present between the small radius portion  111   b  and the load bearing portion  4   e , with which the development unit  4  is provided. Referring to  FIG. 4 , the radius of the large diameter portion  111   c  is large enough for the separation cam  111  to come into contact with the load bearing portion  4   e  and make the development unit  4  pivot by an angle large enough to move the development  4  into the position (first separation position) in which it to keep the development roller  40  separated by a distance of L 1  from the photosensitive drum  1 . 
         [0053]    Referring to  FIG. 4 , when the apparatus main assembly  100  is not operating, the separation cam  111  is in a position (which hereafter will be referred to as first separation cam position) in which its large radius portion  111   a  is in contact with the load bearing portion  4   e . More specifically, as the separation cam  111  is rotated into the first position, the load bearing portion  4   e  is pressed by the large radius portion  111   a . Thus, the development unit  4  is made to rotate about the connective pins  37  in the direction to separate the development roller  40  from the development roller  40 . Thus, when the separation cam  111  is in the first position, the development roller  40  remains separated from the photosensitive drum  1  by a distance of L 1 . With the development roller  40  remaining separated from the photosensitive drum, even if the cartridge  7  is left unused for a long time in the cartridge bay  90 , the elastic layer of the development roller  40  is not deformed. Therefore, it does not occur that if the cartridge  7  is left unused for a long time in the cartridge bay  90 , an image which is nonuniform in density is formed. 
         [0054]    As an image forming operation is started by a print signal, the separation cam  111  is moved (rotated) into a position (which hereafter will be referred to as second separation cam position, shown in  FIG. 3 ) in which its small radius portion opposes the load bearing portion  4   e  of the development unit  4 . When the separation cam  111  is in this position, there is a gap T between the load bearing portion  4   e  and the small radius portion  111   b , allowing the resiliency of the compression springs  53  to press the development roller  40  on the photosensitive drum  1  so that a preset amount of contact pressure is provided between the development roller  40  and photosensitive drum  1 . Therefore, when the separation cam  111  is in the second separation cam position, the image forming apparatus is actually ready for image formation. 
       (Separating Members  50  and  51  of Process Cartridge) 
       [0055]    Next, the mechanism for keeping the separating members  50  and  51  of the cartridge  7  engaged, or disengaging the separating members  50  and  51 , will be described. 
         [0056]      FIG. 6  is a perspective view of the apparatus main assembly  100 , and one of the process cartridges  7  which is being mounted into the main assembly  100 .  FIGS. 7 and 10  are external perspective views of the cartridge  7 , as seen from the downstream and upstream sides, respectively, in terms of the cartridge mounting direction. 
         [0057]    The cartridge  7  has a pair of separating members  50  ( FIG. 7) and 51  ( FIG. 10 ), which are at the downstream end (rear end) and upstream end (front end), respectively, in terms of the cartridge mounting direction (direction indicated by arrow mark E in  FIG. 5 ). That is, the separating members  50  and  51  are at the lengthwise ends of the process cartridge  7 , one for one. On the other hand, each of the cartridge bays of the apparatus main assembly  100  is provided with a pair of disengaging portions  57  and  58  for disengaging the separating members  50  and  51 , respectively. 
       (Structure of Mechanism for Keeping Engaged, or Disengaging, Separating Member  50 ) 
       [0058]    First, the structure of the mechanism for keeping engaged, or disengaging the separating member  50  will be described.  FIG. 8  is a perspective view of the separating member  50  held by the development unit  4 , showing how the separating member  50  is held by the development unit  4 .  FIG. 9  is a side view of the separating member  50 , and the separating member engaging portion (hole) of the photosensitive member unit  26 .  FIG. 9(   a ) shows the separation member  50  and separating member engaging portion of the photosensitive member unit  26 , which are in engagement, whereas  FIG. 9(   b ) shows them which are in separation. For the purpose of showing the portion of the separating member, which is on the inward side of a cover  62  for the separating member  50 , the cover  62  is outlined with a broken line. 
         [0059]    Referring to  FIGS. 7-9 , the separating member  50  is supported by the supporting portion  4   f  of the development unit  4 . More specifically, the shaft  50   a  of the separating member  50  is rotatably supported by the supporting portion  4   f  of the development unit  4 , and is prevented from disengaging from the supporting portion  4   f , by the cover  62 . 
         [0060]    When the separating member  50  is in the state shown in  FIG. 9(   a ), the engaging portion  50   b  of the separating member  50  is in the hole  26   e  of the photosensitive member unit  26  (this position of separating member  50 , shown in  FIG. 9(   a ), will be referred to as separation position). That is, when the separating member  50  is in the separation position, the development unit  4  is in its second position, in which it keeps the development roller  40  separated from the photosensitive drum  1 . 
         [0061]    Prior to the mounting of the cartridge  7  into the apparatus main assembly  100 , the separating member  50  is in the state shown in  FIG. 9(   a ). Then, as the cartridge  7  is mounted into the apparatus main assembly  100 , the separating member  50  is disengaged as shown in  FIG. 9(   b ). 
         [0062]    More specifically, as the cartridge  7  is inserted into the cartridge bay  90 , in the direction indicated by an arrow mark E, with the separating member  50  being in the above described separation position, the inward movement of the cartridge  7  causes the engaging portion  50   c  of the separating member  50  to come into contact with the separating member disengaging portion  57  of the apparatus main assembly  100 . Then, as the cartridge  7  is inserted further into the cartridge bay  90 , the engaging portion  50   b  of the separating member  50  is pushed by the separating member disengaging portion  57 , being thereby moved out of the hole  26   e . Thus, the separating member  50  is made to rotate about the shaft  50   a  in the direction indicated by an arrow mark F, by the separating member disengaging portion  57 . In other words, as the cartridge  7  is inserted into the apparatus main assembly  100 , the separating member  50  comes into contact with the separating member disengaging portion  57  of the apparatus main assembly  100 , and then, is moved out of the abovementioned separation position; the engaging portion  50   b  is moved out of the hole  26   e . As a result, the development roller  40  comes into contact with the photosensitive drum  1 . In other words, as the cartridge  7  is mounted into the cartridge bay  90 , the separating members  50  and  51  are moved out of the abovementioned separation positions, and then are moved into their retreats. 
         [0063]    As the development unit  4  is freed from the restraint imposed by the separating member  50 , it is ready to be pivoted by the force generated by the compression springs  53 , into the second position, that is, the position in which it keeps the development roller  40  in contact with the photosensitive drum  1 . 
       (Structure of Mechanism for Keeping Engaged, or Separating, Separating Member  51 ) 
       [0064]    Next, the structure of the mechanism for keeping engaged, or separating, the separating member  51  will be described. 
         [0065]      FIG. 10  is an external perspective view of the cartridge  7  as seen from the upstream side in terms of the cartridge mounting direction. The separating member  51  is rotatably supported by the shaft  26   f  of the photosensitive member unit  26 , and is prevented from disengaging from the shaft  26   f , by the cover  63 . 
         [0066]      FIG. 11  is a perspective view of the separating member  51 , and the portion of the development unit  4  which is in engagement with the separating member  51 .  FIG. 11  does not show the photosensitive member unit  26 . Referring to  FIG. 11 , when the separating member  51  is kept in the position in which it keeps the development roller  40  separated from the photosensitive drum  1 , the hook-shaped portion  4   i  of the development unit  4  is latched with the regulating portion  51   a  of the separating member  51 . 
         [0067]      FIG. 12  is a side view of the separating member  51  as seen from the direction of cover  63 . In order to show the portion of the separating member  51 , which is on the inward side of the cover  63 , the cover  63  is not shown in  FIG. 12 .  FIG. 12(   a ) shows the separating member  51  when it is in the separation position, and  FIG. 12(   b ) shows the separating member  51  when it is in its retreat. 
         [0068]    When the separating member  51  is in engagement with the hook-shaped portion  4   i  of the development unit  4  as shown in  FIG. 12   a , the end portion of the hook-shaped portion  4   i  of the development unit  4  is in the cleaning means frame  27 , through the hole  27   b  of the cleaning means frame  27 , and the regulating portion  51   a  of the separating member  51  is sandwiched by the end portion of the hook-shaped portion  4   i  of the development unit  4 , and the wall  26   g  of the photosensitive member unit  26 . Thus, the development unit  4  is retained in its second position in which it keeps development roller  40  separated from the photosensitive drum  1 . 
         [0069]    As the cartridge  7  is mounted into the apparatus main assembly  100  as shown in  FIG. 12(   b ), the engaging portion  51   b  of the separating member  51  comes into contact with the separating member disengaging portion  58  of the apparatus main assembly  100 . Then, as the cartridge  7  is inserted further into the apparatus main assembly  100 , the separating member  51  is rotated by the separating member disengaging portion  58  in the direction indicated by an arrow mark G, and therefore, the regulating portion  51   a  of the separating member  51  rotates about the shaft  26   f  in the direction indicated by the arrow mark G, moving therefore away from the hook-shaped portion  4   i . As a result, the hook-shaped portion  4   i  loses its support; in other words, the development unit  4  is freed from the separating member  51 . 
         [0070]    As the development unit  4  is freed from the separating member  51 , it is allowed to be rotated by the force generated by the compression springs  53 , into the position (contact position) in which it keeps the development roller  40  in contact with the photosensitive drum  1 . 
       (Mounting of Process Cartridge  7  into Apparatus Main Assembly  100  (Cartridge Bay  90 )) 
       [0071]    Next, the operation for mounting the cartridge  7  into the apparatus main assembly  100  will be described. 
         [0072]      FIG. 13  is a front view of one of the cartridge bays  90  of the apparatus main assembly  100 , and the cartridge  7  which is being mounted into the cartridge bay  90 . When the cartridge bay  90  and cartridge  7  are in the state shown in  FIG. 13 , that is, in the state in which the mounting of the cartridge  7  has not been completed, the separating members  50  and  51  are yet to be disengaged. Thus, there is a gap L 2  (distance), which is provided by the separating members  50  and  51 , between the development roller  40  and photosensitive drum  1 . This distance L 2  is greater than the distance L 1  provided by the separation cam  111  (L 1 &lt;L 2 ). Therefore, while the cartridge  7  is mounted into the apparatus main assembly  100 , there is a gap T 2  between the load bearing portion  4   e  of the development unit  4  and the large radius portion  111   c  of the separation cam  111 . 
         [0073]      FIG. 14  is a side view (as seen from development unit side) of one of the cartridge bays  90  of the apparatus main assembly  100 , and the cartridge  7  which is being mounted into the cartridge bay  90 .  FIG. 15  is a side view (as seen from development unit side) of one of the cartridge bays  90  of the apparatus main assembly  100 , and the cartridge  7  which has just been completely mounted into the cartridge bay  90 . 
         [0074]    As the cartridge  7  is inserted into the cartridge bay  90  far enough to reach the position shown in  FIG. 14 , the load bearing portion  4   e  of the development unit  4  overlaps with the separation cam  111  (cross-hatched portion R in  FIG. 14 ). As described above, there is the gap T 2  between the load bearing portion  4   e  and the functional surface of the separation cam  111  (large radius portion  111   c ). Therefore, the cartridge  7  is not subjected to an additional amount of load; the amount of force necessary to mount the cartridge  7  into the cartridge bay  90  does not increase. 
         [0075]    Then, as the cartridge  7  is inserted deep enough to reach the position shown in  FIG. 15 , the separating members  50  and  51  come into contact with the separating member disengaging portions  57  and  58  of the apparatus main assembly  100 . Then, as the cartridge  7  is inserted further, the separating members  50  and  51  are disengaged by the separating member disengaging portions  57  and  58 , respectively. While the separating members  50  and  51  are disengaged, the load bearing portion  4   e  and the functional surface of the separation cam  111  (large radius portion  111   c ) remain opposed to each other, without contacting with each other (with presence of gap T 2 ). In other words, before the separating members  50  and  51  are disengaged, at least a part of the load bearing portion  4   e  overlaps with at least a part of the separation cam  111 , in terms of the direction perpendicular to the cartridge mounting direction (indicated by arrow mark E) (direction in which load bearing portion  4   e  is moved to be placed in contact with, or separated from, separation cam  111  (direction indicated by arrow mark M)). In other words, as the cartridge  7  is inserted deep enough into the cartridge bay  90  to make it possible for the load bearing portion  4   e  to be placed in contact with the large radius portion  111   c , the large radius portion  111   c  opposes the load bearing portion  4   e  without coming in contact with the load bearing portion  4   e . Here, the direction in which the load bearing portion  4   e  is moved to be placed in contact with, or to be separated from, the separation cam  111  is the same direction in which the load bearing portion  4   e  is moved when the development roller  40  is placed in contact with, or separated from, the photosensitive drum  1 . Further, it is after the cartridge  7  is inserted far enough to make it possible for the load bearing portion  4   e  to be placed in contact with the large radius portion  111   c  that the separating member disengaging portions  57  and  58  of the apparatus main assembly  100  come into contact with the separating members  50  and  51  to move the separating members  50  and  51  out of the abovementioned separation positions, respectively. 
         [0076]    As the separating members  50  and  51  are moved out of their separation positions, the load bearing portion  4   e  of the development unit  4  comes into contact with the large radius portion  111   c  of the separation cam  111 , in the cross-hatched portion H in  FIG. 15 , keeping the development roller  40  separated from the photosensitive drum  1 , in the apparatus main assembly  100 . That is, as the separating member disengaging portions  57  and  58  move the separating members  50  and  51  out of the abovementioned separation position, by coming into contact with the separating members  50  and  51 , the load bearing portion  4   e  comes into contact with the large radius portion  111   c , keeping thereby the development roller  40  separated from the photosensitive drum  1 . 
         [0077]    As described above, in this embodiment, while the cartridge  7  is mounted into the apparatus main assembly  100 , the development roller  40  is prevented from coming into contact with the photosensitive drum  1 . Therefore, it does not occur that the shock which occurs as the development roller  40  comes into contact with the photosensitive drum  1  is transmitted to the hand of a user. In other words, the cartridge  7  in this embodiment is superior in operability to a process cartridge in accordance with the prior art. Also in this embodiment, when the cartridge  7  is mounted into the apparatus main assembly  100  (cartridge bay  90 ), the load to which a process cartridge in accordance with the prior art is subjected when it is mounted into the main assembly of an image forming apparatus in accordance with the prior art is not present. That is, it is only when the separating members  50  and  51  are disengaged that the cartridge  7  in this embodiment is subjected to a certain amount of load. Therefore, the cartridge  7  in this embodiment is significantly smaller in the amount of force necessary to mount it into the apparatus main assembly  100  than a process cartridge in accordance with the prior art. 
       Embodiment 2 
       [0078]    Next, the process cartridge and image forming apparatus in the second embodiment of the present invention will be described with reference to the appended drawings.  FIG. 16  is a front view of one of the process cartridge bays  90  of the main assembly  100  of the image forming apparatus in this embodiment, and the process cartridge  7  in the cartridge bay  90 .  FIG. 17  is a perspective view of one of the process cartridge bays  90  of the apparatus main assembly  100 , as seen from the front side of the apparatus main assembly  100 . The portions of the apparatus main assembly  100  in this embodiment, the descriptions of which are duplicates of those of the counterparts in the first embodiment, will be given the same referential symbols as those given for the description of the first embodiment, and will not be described. 
         [0079]    Referring to  FIGS. 16 and 17 , the cartridge  7  and image forming apparatus in this embodiment are the same in structure as those in the first embodiment, except that each of the process cartridge bays  90  in this embodiment is provided with a portion having a slanted surface  61 , which is on the upstream side of the separation cam  111  in terms of the cartridge mounting direction. 
         [0080]    As the cartridge  7  is mounted into the apparatus main assembly  100  in the direction indicated by an arrow mark E, the slanted surface  61  comes into contact with the load bearing portion  4   e  and reactively pushes the load bearing portion  4   e . As a result, the development unit  4  is moved into the second separation position. The portion having the slanted surface  61  is shaped so that the slanted surface  61  is slanted reward, and also, so that as the cartridge  7  is mounted into the apparatus main assembly  100 , the slanted surface  61  makes the load bearing portion  4   e  retreat by the same distance as, or more distance than the large radius portion  111   c.    
         [0081]    When the cartridge  7  is in the position shown in  FIG. 16 , the operation for mounting the cartridge  7  has not been completed, and the separating members  50  and  51  have not been disengaged. Thus, a gap L 3  (distance) between the development roller  40  and photosensitive drum  1  shown in  FIG. 16 , is the gap provided by the separating members  50  and  51 . This gap L 3  is smaller than the gap L 1  provided between the development roller  40  and photosensitive drum  1  by the separation cam  111  (L 1 &gt;L 3 ). Thus, during the operation for mounting the cartridge  7 , the load bearing portion  4   e  and large radius portion overlap with each other across the cross-hatched area K in  FIG. 16 . Therefore, before the completion of the operation for mounting the cartridge  7 , the load bearing portion  4   e  of the development unit  4  must be moved in the rightward in  FIG. 15 , by a distance equivalent to the size of the cross-hatched portion in  FIG. 15 , to be placed in contact with the functional surface of the separation cam  111 . 
         [0082]    Referring to  FIG. 17 , in this embodiment, however, the cartridge bay  90  is provided with the portion having the slanted surface  61 , which is on the upstream side of the separation cam  111  in terms of the cartridge mounting direction. Therefore, as the cartridge  7  is inserted into the cartridge bay  90 , the load bearing portion  4   e  comes into contact with the slanted surface  61 . Thus, as the cartridge  7  is inserted further, it is smoothly (easily) displaced rightward in the drawing, being enabled to smoothly come into contact with the functional surface of the large radius portion  111   c.    
         [0083]    Incidentally, in this embodiment, the apparatus main assembly  100  is provided with the slanted surface  61 . However, it may be the cartridge  7  that is provided with the slanted surface  61 . In the case where the cartridge  7  is provided with the slanted surface  61 , the slanted surface  61  must be positioned on the downstream side of the load bearing portion  4   e  in terms of the cartridge mounting direction. 
         [0084]    Next, the operation for mounting the process cartridge will be described. 
       (Operation for Mounting of Process Cartridge) 
       [0085]      FIGS. 18 and 19  are side views (as seen from development unit side) of one of the cartridge bays  90  of the apparatus main assembly  100 , and the cartridge  7  which is being mounted into the cartridge bay  90 .  FIG. 20  is a side view (as seen from development unit side) of one of the cartridge bays  90  of the apparatus main assembly  100 , and the cartridge  7  which has just been completely mounted into the cartridge bay  90 . First, the cartridge  7  is inserted into the cartridge bay  90  in the cartridge mounting direction (indicated by arrow mark E). As the cartridge  7  reaches the position shown in  FIG. 18 , the load bearing portion  4   e  begins to slide on the slanted surface  61 . Then, as the cartridge  7  is inserted further, it slides onto the separation cam  111 . 
         [0086]    Thereafter, as the cartridge  7  is inserted deeper so that it moves into the position shown in  FIG. 19 , the force bearing portion  4   e  becomes separated from the slanted surface  61 , and comes into contact with only the separation cam  111  (large radius portion  111   c ), only in the cross-hatched area H. The cartridge  7  is to be inserted further thereafter. As the cartridge  7  is inserted deep enough for the cartridge  7  to be moved into the position shown in  FIG. 20 , the separating members  50  and  51  come into contact with the separating member disengaging portions  57  and  58  of the apparatus main assembly  100 , and are prevented by the separating member disengaging portions  57  and  58  from moving further into the cartridge bay  90 . Thus, as the cartridge  7  is moved further into the apparatus main assembly  100  (cartridge bay  90 ), the separating members  50  and  51  are disengaged (separating members  50  and  51  are made to retreat from the abovementioned separation position). That is, when the separating members  50  and  51  begin to be disengaged, the force bearing portion  4   e  and separation cam  111  (large radius portion  111   c ) are opposing each other, being ready to be placed in contact with each other. In other words, in terms of the direction perpendicular to the cartridge mounting direction (in terms of the direction (indicated by arrow mark M) in which the force bearing portion  4   e  is moved to be placed in contact with, or separated from, the separation cam  111 , at least a part of the force bearing portion  4   e  overlaps with a part of the separation cam  111 , before the separating members  50  and  51  are disengaged. Here, the direction in which the load bearing portion  4   e  is moved to be placed in contact with, or separated from, the functional surface of the separation cam  111  is the same as the direction in which the load bearing portion  4   e  moved to place the development roller  40  in contact with the photosensitive drum  1 , or separate the development roller  40  from the photosensitive member unit  26 . 
         [0087]    As described above, in this embodiment, during the operation for mounting the cartridge  7 , the development roller  40  is prevented from coming into contact with the photosensitive drum  1 . Therefore, in the case of the process cartridge  7  and image forming apparatus in this embodiment, the shock which occurs when a process cartridge in accordance with the prior art is mounted, and which is attributable to the abrupt contact between the development roller  40  and photosensitive drum  1 , does not occur. Therefore, in the case of the process cartridge and image forming apparatus in this embodiment, a shock is not transmitted to the hand of a user during the operation for mounting the process cartridge. In other words, the process cartridge and image forming apparatus in this embodiment are superior in operability to a process cartridge and an image forming apparatus, which are in accordance with the prior art. 
         [0088]    Further, in this embodiment, a part of the force necessary to mount the process cartridge  7  into the apparatus main assembly  100  (cartridge bay  90 ) is the load to which the load bearing surface  4   e  is subjected as it made to slide on the slanted surface  61 . In this embodiment, however, the portion having the slanted surface  61  is shaped so that the slanted surface  61  is long enough (in terms of cartridge mounting direction) for the slanted surface  61  to displace the load bearing surface  4   e  only very gradually. Therefore, as the cartridge  7  is inserted into the apparatus main assembly  100  (cartridge bay  90 ), the amount of force necessary for mounting the cartridge  7  increases only very gradually. 
         [0089]    Also in this embodiment, as the cartridge  7  is inserted into the apparatus main assembly  100  (cartridge bay  90 ), the gap provided between the development roller  40  and photosensitive drum  1  by the separation members  50  and  51  is increased by the slanted surface  61  of the apparatus main assembly  100 . Thus, before the separating members  50  and  51  are disengaged toward the end of the operation for mounting the cartridge  7 , the load to which the engaging portion of the separating member  50  and the engaging portion of the separating member  51 , are subjected up to when the gap between the development roller  40  and photosensitive drum  1  is increased by the slanted surface  61 , are eliminated. Therefore, in this embodiment, the amount of force necessary to disengage the separating members  50  and  51  toward the end of the operation for mounting the cartridge  7  is virtually nil. 
       Embodiment 3 
       [0090]    Next, the process cartridge and image forming apparatus in the third embodiment of the present invention will be described with reference to the appended drawings. The portions of the apparatus main assembly  100  in this embodiment, the descriptions of which are duplicates of those of the counterparts in the first embodiment, will be given the same referential symbols as those given for the description of the first embodiment, and will not be described. 
         [0091]    Referring to  FIGS. 21-24 , the cartridge  7  and image forming apparatus in this embodiment are the same in structure as those in the first embodiment, except that the cartridge  7  in this embodiment is provided with a protective cover  60  (protective member), which functions as a separating member, instead of the separating member  51 . 
         [0092]    That is, both ends of the cartridge  7  (in terms of cartridge mounting direction) are provided with a protective cover  60  for the photosensitive drum  1 . The protective cover  60  on the downstream side is utilized as the separating member ( 50 ), and the protective cover  60  on the upstream side is utilized as the separating member ( 51 ). Next, the protective cover  60  for the photosensitive drum  1  will be described. 
       (Protective Cover  60 ) 
       [0093]    The protective cover  60  is a component formed independently from the cartridge  7 . It is attached to the cartridge  7  to protect the photosensitive drum  1 . 
         [0094]      FIG. 21  is an external perspective view of the cartridge  7  with the protective cover  60 . As will be evident from  FIG. 21 , the protective cover  60  has a pair of ribs  60   a  and  60   b  (slider ribs) which are fitted into the pair of grooves with which the cartridge  7  is provided, and a portion  60   c  for keeping the development roller  40  separated from the photosensitive drum  1  (this portion  60   c  hereafter will be referred to as separating portion  60   c ). 
         [0095]    The protective cover  60  is attached to the cartridge  7  by sliding the sliding ribs  60   a  and  60   b  into the grooves  26   h  and  26   i , with which the photosensitive member unit  26  of the cartridge  7  is provided. Thus, the protective cover  60  is slidable relative to the cartridge  7  in the lengthwise direction of the cartridge  7 . 
         [0096]    The separating portion  60   c  is at the upstream end in terms of the cartridge mounting direction, and extends perpendicularly downward from the main portion of the protective cover  60 . The separating portion  60   c  remains sandwiched between the contact area  4   h  of the development unit  4  and the contact area  26   k  of the photosensitive drum  1  to keep the development unit  4  in the second separation position. 
         [0097]    On the other hand, to the downstream end of the cartridge  7 , a separating member  50  is attached to keep the development unit  4  in the position in which it keeps the development roller  40  separated from the photosensitive drum  1 . 
       (Operation for Mounting Process Cartridge) 
       [0098]      FIG. 22  is a perspective view of the cartridge  7  which is being mounted into one of the cartridge bays  90 .  FIG. 23  is a side view (as seen from development unit side) of one of the cartridge bays  90  of the apparatus main assembly  100 , and the cartridge  7  which is being mounted into the cartridge bay  90 .  FIG. 24  is a side view (as seen from development unit side) of one of the cartridge bays  90  of the apparatus main assembly  100 , and the cartridge  7  which has just been completely mounted into the cartridge bay  90 . 
         [0099]    As will be evident from  FIGS. 22 and 23 , in order to properly mount the cartridge  7  into the apparatus main assembly  100 , a user is to hold the cartridge  7  by the handle portion  60   d  of the protective cover  60 , and to insert the cartridge  7  into the apparatus main assembly  100  (cartridge bay  90 ) so that the protective cover  60  slides into the protective cover slot portion  100   b  of the apparatus main assembly  100  (cartridge bay  90 ). Then, the cartridge  7  is to be inserted further into the apparatus main assembly  100  (cartridge bay  90 ) by sliding the cartridge  7  relative to the protective cover  60 . 
         [0100]    Referring to  FIG. 23 , as the cartridge  7  is inserted further into the apparatus main assembly  100  by sliding the cartridge  7  along the protective cover  60 , the separating portion  60   c  is disengaged from the contact area  4   h  of the development unit  4  and the contact area  26   k  of the cleaning unit  26 . In other words, the upstream end of the development unit  4 , in terms of the cartridge mounting direction, is freed from the separating portion  60   c.    
         [0101]    Then, the cartridge  7  is to be slid further into the apparatus main assembly  100  after the development unit  4  is freed from the separating portion  60   c . As the cartridge  7  is slid further into the apparatus main assembly  100 , the protective cover  60  is disengaged from the cartridge  7 . 
         [0102]    During the above described movement of the cartridge  7 , the separating member  50 , that is, the separating member at the upstream end, in terms of the cartridge mounting direction, remains engaged. Therefore, the development unit  4  remains restricted in movement (being thereby kept in the position in which it keeps the development roller  40  separated from the photosensitive drum  1 ), at the upstream end. Then, as the cartridge  7  is inserted further into the position shown in  FIG. 23 , the separating member  50  comes into contact with the separating member disengaging portion  57  of the apparatus main assembly  100 , and then, the separating member  50  is disengaged by the further insertion of the cartridge  7 . 
         [0103]    Incidentally, the disengagement of the separating member  50  occurs immediately before the completion of the operation for mounting the cartridge  7 . Therefore, it is possible that immediately before and after the disengagement of the separating member  50 , the positional relationship between the force bearing portion  4   e  of the development unit  4  and the separation cam  111  will be the same as that in the first embodiment or second embodiment. That is, in this embodiment, the force bearing portion  4   e  may come into contact with the separation cam  111  after the disengagement of the separating member  50 , as in the case of the first embodiment, or before the disengagement of the separating member  50 , as in the case of the second embodiment. 
         [0104]    Thus, the relationship between the force bearing  4   e  and separation cam  111  in this embodiment can provide the same effects as those provided in the first and second embodiment. That is, the process cartridge  7  and image forming apparatus in this embodiment is significantly smaller in the amount of force required to mount the process cartridge  7  into the image forming apparatus, than a process cartridge and an image forming apparatus, which are in accordance with the prior art. That is, the process cartridge  7  and image forming apparatus in this embodiment is significantly superior to a process cartridge and an image forming apparatus, which are in accordance with the prior art, in terms of the operability which concerns the operation which a user has to perform to mount the cartridge  7  into the image forming apparatus. 
         [0105]    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. 
         [0106]    This application claims priority from Japanese Patent Applications Nos. 333026/2006 and 277091/2007 filed Dec. 11, 2006 and Oct. 25, 2007, respectively, which are hereby incorporated by reference.