Patent Publication Number: US-8526851-B2

Title: Process cartridge and electrophotographic image forming apparatus

Description:
This application is a divisional of U.S. patent application Ser. No. 12/699,438, filed Feb. 3, 2010. 
    
    
     FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to a process cartridge and an electrophotographic image forming apparatus using the process cartridge. 
     Here, an electrophotographic image forming apparatus refers to an apparatus which forms an image on recording material (medium) with the use of electrophotographic image forming method. As the example of an electrophotographic image forming apparatus, an electrophotographic copying machine, an electrophotographic printer (for example, laser beam printer, LED printer, etc.), a facsimile machine, a word processor, etc., may be included. 
     Further, the process cartridge refers to a cartridge in which at least a developing means as a process means and an electrophotographic photosensitive member are integrally supported, and which is detachably mountable to a main assembly of an electrophotographic image forming apparatus. 
     In the electrophotographic image forming apparatus using an electrophotographic image forming process, a process cartridge system, in which an electrophotographic photosensitive drum and processing means acting on the electrophotographic photosensitive drum are integrally supported in a cartridge which is detachably mountable to the main assembly of the electrophotographic image forming apparatus, has been conventionally employed. According to this process cartridge system, it is possible for a user to perform maintenance of the apparatus by himself (herself) without relying on a service person, so that operativity can be significantly improved. Therefore, the process cartridge system is widely in used in the electrophotographic image forming apparatus. 
     An apparatus constitution in which such a process cartridge is mounted to the image forming apparatus along an axial direction of the photosensitive drum has been known. 
     Further, after the process cartridge was mounted to the image forming apparatus, the electrophotographic photosensitive drum and a developing roller which was the process means acting on the photosensitive drum were left standing in a contact state, so that the developing roller was deformed by a contact pressure thereof with respect to the photosensitive drum in some cases. With respect to this deformation, a measure has been taken by optimizing a material of the developing roller. However, in order to further stabilize an image quality, it is desirable that the photosensitive drum and the developing roller are kept in a mutually separated state. 
     Therefore, in such a mounting constitution that the process cartridge is mounted to the image forming apparatus along the axial direction of the photosensitive drum, a contact and separation constitution for moving the developing roller toward and away from the photosensitive drum has been known (U.S. Patent Application Publication No. US2008/0138107). 
     A constitution which is under further development of the above-described constitution and is unknown is shown in  FIGS. 9 and 10 . First, a process cartridge  1  through shafts  27 R and  27 L. Then, a portion to be urged  30  ( 30   a ,  30   b ) for separating a developing roller  21  from a photosensitive drum  11  by receiving an acting force from the image forming apparatus is provided at a part of the developing unit  20 . When the process cartridge  1  is mounted, the portion to be urged  30  ( 30   a ,  30   b ) is urged (pressed) by a guide member  102  provided to the image forming apparatus, so that the developing roller  21  is moved away from the photosensitive drum  11 . 
     In this constitution, a hole  103  ( 103   a ,  103   b ) is formed at a part of a guide surface  102   b  of the guide member  102  along which the portion to be urged  30  ( 30   a ,  30   b ) slides, and an urging portion  104  ( 104   a ,  104   b ) actable on the portion to be urged  30  ( 30   a ,  30   b ) is provided at the bottom of the hole  103  ( 103   a ,  103   b ). As a result, in a state in which the process cartridge  1  is mounted to the image forming apparatus, the photosensitive drum  11  and the developing roller  21  are kept in a separated state. Further, the guide surface  102   b  of the guide member  102  is made higher than the urging portion  104 , whereby the urging portion  104  is prevented from being abraded by friction during the mounting of the process cartridge  1  to stabilize an amount of separation (spacing) of the developing roller  21 . 
     The mounting operation of the process cartridge  1  in the above-described constitution will be described with reference to  FIGS. 10(   a ) to  10 ( d ). The process cartridge  1  is mounted to the image forming apparatus with respect to an arrow Z direction indicated in  FIG. 10(   a ). At this time, the portion to be urged  30   b  is moved in an arrow Y direction along a tapered portion  102   a  provided to the guide member  102  ( FIGS. 10(   a ) and  10 ( b )). 
     However, in the above-described constitution, when the mounting operation is further continued, the portion to be urged  30   b  of the process cartridge  1  engages into the hole  103   a  provided to the guide member  102  as shown in  FIG. 10(   c ). Thereafter, by continuing the mounting, as shown in  FIG. 10(   d ), the portion to be urged  30   b  runs from the hole  103   a  onto a guide surface  102   b  as shown in  FIG. 10(   d ) (arrow X). At this time, there was a possibility of an increase in mounting load of the process cartridge  1 . 
     The present invention further develops the above-described constitution. 
     As described above, in the constitution shown in  FIGS. 10(   a ) to  10 ( d ), in the mounting process of the process cartridge  1 , the mounting load was temporarily increased, so that a feeding of smooth mounting was not obtained in some cases. 
     SUMMARY OF THE INVENTION 
     A principal object of the present invention is to provide a process cartridge improved in operativity when the process cartridge is mounted to an apparatus main assembly. 
     Another object of the present invention is to provide an electrophotographic image forming apparatus using the process cartridge. 
     According to an aspect of the present invention, there is provided an electrophotographic image forming apparatus comprising: 
     a process cartridge comprising a photosensitive member unit which includes an electrophotographic photosensitive member and comprising a developing unit which includes a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive member and which is movable toward and away from the photosensitive member unit in order that the electrophotographic photosensitive member and the developing roller can be moved toward and away from each other; and 
     a main assembly of the electrophotographic image forming apparatus to which the process cartridge is mountable along a longitudinal direction of the electrophotographic photosensitive member, 
     wherein (a) the developing unit includes a first portion to be urged provided on an upstream side with respect to a mounting direction of the process cartridge and includes a second portion to be urged provided on a downstream side with respect to the mounting direction, 
     wherein (b) the main assembly comprises: 
     a guide portion for guiding the first portion to be urged and the second portion to be urged during mounting of the process cartridge in the main assembly, wherein the guide portion includes, in a state in which the process cartridge is mounted in the main assembly, a first hole for permitting thereinto entry of the first portion to be urged and a second hole for permitting thereinto entry of the second portion to be urged; 
     a first urging portion for urging the first portion to be urged, in a state in which the first member to be urged enters the first hole, so as to move the developing unit with respect to the photosensitive member unit; and 
     a second urging portion for urging the second portion to be urged, in a state in which the second member to be urged enters the second hole, so as to move the developing unit with respect to the photosensitive member unit, and 
     wherein (c) the second portion to be urged is non-enterable into the first hole. 
     According to another aspect of the present invention, there is provided an electrophotographic image forming apparatus comprising: 
     a process cartridge comprising a photosensitive member unit which includes an electrophotographic photosensitive member and comprising a developing unit which includes a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive member and which is movable toward and away from the photosensitive member unit in order that the electrophotographic photosensitive member and the developing roller can be moved toward and away from each other; and 
     a main assembly of the electrophotographic image forming apparatus to which the process cartridge is mountable along a longitudinal direction of the electrophotographic photosensitive member, 
     wherein (a) the main assembly includes a first urging portion provided on an upstream side with respect to a mounting direction of the process cartridge and includes a second urging portion provided on a downstream side with respect to the mounting direction, 
     wherein (b) the developing unit comprises: 
     a portion to be guided for being guided by the first urging portion and the second urging portion during mounting of the process cartridge in the main assembly, wherein the portion to be guided includes, in a state in which the process cartridge is mounted in the main assembly, a first hole for permitting thereinto entry of the first urging portion and a second hole for permitting thereinto entry of the second urging portion; 
     a first portion to be urged for being urged by the first urging portion, in a state in which the first member to be urged enters the first hole, so as to move the developing unit with respect to the photosensitive member unit; and 
     a second portion to be urged for being urged by the second urging portion, in a state in which the second member to be urged enters the second hole, so as to move the developing unit with respect to the photosensitive member unit, and 
     wherein (c) the first urging portion is non-enterable into the second hole. 
     According to a further aspect of the present invention, there is provided a process cartridge mountable to a main assembly of an electrophotographic image forming apparatus, along a longitudinal direction of the image forming apparatus, which includes a guide portion including a first hole and a second hole, a first urging portion provided to the first hole, and a second urging portion provided to the second hole, the process cartridge comprising: 
     a photosensitive member unit which includes an electrophotographic photosensitive member; 
     a developing unit which includes a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive member and which is movable toward and away from the photosensitive member unit in order that the electrophotographic photosensitive member and the developing roller can be moved toward and away from each other; 
     a first portion to be urged provided on an upstream side with respect to a mounting direction of the process cartridge: and 
     a second portion to be urged provided on a downstream side with respect to the mounting direction, 
     wherein the first portion to be urged and the second portion to be urged are guided by the guide portion during mounting of the process cartridge in the main assembly, 
     wherein in a state in which the process cartridge is mounted in the main assembly, the first portion to be urged enters the first hole and the second portion to be urged enters the second hole, 
     wherein the first portion to be urged is urged by the first urging portion, in a state in which the first member to be urged enters the first hole, so as to move the developing unit with respect to the photosensitive member unit; and 
     wherein the second portion to be urged is urged by the second urging portion, in a state in which the second member to be urged enters the second hole, so as to move the developing unit with respect to the photosensitive member unit, and 
     wherein the second portion to be urged is non-enterable into the first hole. 
     According to a still further aspect of the present invention, there is provided a process cartridge mountable to a main assembly of an electrophotographic image forming apparatus, along a longitudinal direction of the image forming apparatus, which includes a first urging portion and a second urging portion, the process cartridge comprising: 
     a photosensitive member unit which includes an electrophotographic photosensitive member; and 
     a developing unit which includes a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive member and which is movable toward and away from the photosensitive member unit in order that the electrophotographic photosensitive member and the developing roller can be moved toward and away from each other; 
     wherein the developing unit comprises: 
     a portion to be guided for being guided by the first urging portion and the second urging portion during mounting of the process cartridge in the main assembly, wherein the portion to be guided includes a first hole, provided on an upstream side with respect to a mounting direction of the process cartridge, for permitting thereinto entry of the first urging portion in a state in which the process cartridge is mounted in the main assembly, and includes a second hole, provided on a downstream side with respect to the mounting direction, for permitting thereinto entry of the second urging portion in the state in which the process cartridge is mounted in the main assembly; 
     a first portion to be urged for being urged by the first urging portion, in a state in which the first member to be urged enters the first hole, so as to move the developing unit with respect to the photosensitive member unit; and 
     a second portion to be urged for being urged by the second urging portion, in a state in which the second member to be urged enters the second hole, so as to move the developing unit with respect to the photosensitive member unit, and 
     wherein the second hole is configured so that the first urging portion is non-enterable into the second hole. 
     These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of an image forming apparatus. 
         FIG. 2  is a sectional view of a principal portion of a process cartridge. 
         FIG. 3  is a schematic view of a developing device contact and separation mechanism and its peripheral portion. 
         FIGS. 4(   a ) to  4 ( c ) are schematic views for illustrating an operation for separating a developing device. 
         FIG. 5  is a schematic view for illustrating mounting of the process cartridge to the image forming apparatus. 
         FIGS. 6(   a ) to  6 ( d ) are detailed views showing a portion to be urged in a mounting process. 
         FIG. 7  is a schematic view showing a developing device contact and separation mechanism and its peripheral portion in Embodiment 2. 
         FIGS. 8(   a ) to  8 ( d ) are detailed views showing a portion to be urged in a mounting process in Embodiment 2. 
         FIG. 9  is a schematic view showing a constitution of a conventional developing device separation portion. 
         FIGS. 10(   a ) to  10 ( d ) are detailed views showing the developing device separation portion in a conventional mounting process. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     The process cartridge and an electrophotographic color image forming apparatus (hereinafter referred to as an image forming apparatus) in Embodiment 1 of the present invention will be described with reference to the drawings. 
     (General Structure of Image Forming Apparatus) 
     First, the general structure of the image forming apparatus will be described with reference to  FIG. 1 . An image forming apparatus  100  shown in  FIG. 1  has four mounting portions  101  ( 101   a - 101   d ) ( FIG. 5 ), as mounting means for four process cartridges, which are arranged and inclined with respect to a horizontal direction. The process cartridges  1  ( 1   a - 1   d ), which are mounted into the mounting portions  101 , are provided with electrophotographic photosensitive drums  11  ( 11   a ,  11   b ,  11   c  and  11   d ), respectively. 
     The above-mentioned electrophotographic photosensitive drum (hereinafter referred to as photosensitive drum)  11  is rotationally driven in a direction indicated by an arrow Q in the figure by a driving member (unshown). Around each of the photosensitive drum  11 , the following process means acting on the photosensitive drum  11  are disposed along its rotational direction in the order of a cleaning member  15  ( 15   a ,  15   b ,  15   c , or  15   d ) for removing a developer remaining on the photosensitive drum  1  surface after transfer (hereinafter referred to as toner); a charging roller  12  ( 12   a ,  12   b ,  12   c , or  12   d ) for uniformly charging the surface of the photosensitive drum  11 ; a developing unit  20  ( 20   a ,  20   b ,  20   c , or  20   d ) for developing an electrostatic latent image with the toner; a scanner unit  160  for forming the electrostatic latent image on the surface of the photosensitive drum  11  by irradiation with a laser beam on the basis of image information; and an intermediary transfer belt  110  onto which four toner images formed on the photosensitive drums  11  are to be collectively transferred. The photosensitive drum  11 , the cleaning member  15 , the charge roller  12 , and the developing unit  20  are integrally supported to constitute a process cartridge  1 . The process cartridge  1  is detachably mountable to a main assembly  100   a  of the image forming apparatus  100  along a rotational axis (shaft) direction of the photosensitive drum  11  by a user. 
     The intermediary transfer belt  110  is stretched around a driving roller  111  and a tension roller  112 . Inside the intermediary transfer belt  110 , four primary transfer rollers  113  ( 113   a - 113   d ) are disposed oppositely to the photosensitive drums  11  ( 11   a - 11   d ). To the intermediary transfer belt  110 , a transfer bias is applied by a bias applying means (unshown). 
     A toner image formed on each of the surface of the photosensitive drum  11  is successively primary-transferred onto the intermediary transfer belt  110  by rotation of the photosensitive drum  11  in the direction indicated by an arrow Q, rotation of the intermediary transfer belt  110  in the direction indicated by an arrow R, and by application of a positive bias to the primary transfer roller  113 . Then, the four toner images in a superposed state on the intermediary transfer belt  110  are conveyed to the secondary transfer portion  131 . 
     In synchronism with the above-mentioned image forming operation, a sheet S as the recording material is conveyed by a conveying means consisting of a sheet feeding device  120 , a pair of registration rollers  130 , etc. The sheet feeding device  120  has a sheet feeding cassette  121  for accommodating the sheet S, a sheet feeding roller  122  for feeding the sheet S, and a pair of sheet conveying rollers  124  for conveying the fed sheet S. The sheet feeding cassette  121  can be pulled out of the apparatus main assembly  100   a  in the frontward direction in  FIG. 1 . The sheet S is pressed against the sheet feeding roller  122  and is separated one by one by a separation pad  123  (one-side friction sheet separating method), thus being conveyed. 
     The sheet S conveyed from the sheet feeding device  120  is conveyed to the secondary transfer portion  131  by the pair of registration rollers  130 . At the secondary transfer portion  131 , the positive bias is applied to the secondary transfer roller  132 . As a result, the four toner images on the intermediary transfer belt  110  are secondary-transferred onto the conveyed sheet S. 
     A fixing portion  140  as a fixing means fixes the toner images on the conveyed sheet S by applying heat and pressure to the toner images formed on the sheet S. A fixing belt  140   a  is cylindrical and is guided by a belt guide member (unshown) to which a heat generating means, such as a heater is bonded. The fixing belt  140   a  and the pressing roller  140   b , form a fixing nip with a predetermined press-contact force. 
     The sheet S on which the unfixed toner images conveyed from the image forming portions is heated and pressed in the fixing nip. As a result, the unfixed toner images on the sheet S are fixed on the sheet S. Thereafter, the sheet S on which the toner images are fixed is discharged on a sheet discharge tray  151  by a pair of sheet discharge rollers  150 . 
     The toner remaining on the surface of the photosensitive drum  11  after the toner image transfer is removed by the cleaning member  15  ( 15   a - 15   d ). The removed toner is collected in a removed toner chamber  16   a  in the photosensitive member unit  10  ( 10   a - 10   d ) shown in  FIG. 2 . 
     The toner remaining on the intermediary transfer belt  110  after the second transfer onto the sheet S is removed by a transfer belt cleaning device  114 . The removed toner is conveyed through a waste toner conveyance passage (unshown), and is collected in a waste toner collecting container (unshown) located in the rear end portion of the apparatus. 
     (Process Cartridge) 
     Next, the process cartridge  1  in this embodiment will be described with reference to  FIG. 2 .  FIG. 2  is a principal sectional view of the process cartridge  1  containing toner t. Incidentally, the process cartridges  1   a ,  1   b ,  1   c , and  1   d , which contain yellow, magenta, cyan, and black toners t, respectively, have the same constitution. 
     Each process cartridge  1  is divided into a photosensitive member unit  10  and a developing unit  20 . The photosensitive member unit  10  includes the photosensitive drum  11 , charge roller  12  (charging means), and cleaning member  15  (cleaning means). The developing unit  20  includes a developing roller  21  as a developer carrying member. The photosensitive drum  11  is rotatably supported by a cleaning device frame  16  of the photosensitive member unit  10 . The photosensitive drum  11  is rotationally driven correspondingly to the image forming operation by transmitting the driving force from a motor (unshown) to the photosensitive member unit  10 . 
     The charge roller  12  and the cleaning member  15  are disposed on the peripheral surface of the photosensitive drum  11  as described previously. The residual toner removed from the surface of the photosensitive drum  11  by the cleaning member  15  falls into the removed toner chamber  16   a . The cleaning device frame  16  is fitted with a pair of charging roller bearings  13 , which are movable in the direction indicated by an arrow D, which passes through the centers of the charging roller  12  and the photosensitive drum  11 . A shaft  12   j  of the charging roller  12  is rotatably supported by the pair of charging roller bearings  13 . Further, the charging roller bearings  13  are kept pressed toward the photosensitive drum  11  by a charge roller pressing member  14 . 
     The developing unit  20  has the developing roller  21  rotating in contact with the photosensitive drum  11  in the direction indicated by an arrow B, and has a developing device frame  24 . The developing roller  21  is rotatably supported by the developing device frame  24  through shaft supporting member  26  ( 26 R,  26 L) attached to both longitudinal sides of the developing device frame  26 . On the peripheral surface of the developing roller  21 , a toner supplying roller  22  rotatable in contact with the developing roller  21  in the direction indicated by an arrow C, and a developing blade  23  for regulating in thickness the toner layer on the developing roller  21 . Further, to a toner containing portion  24   a  of the developing device frame  24 , a toner conveying member  25  for conveying the contained toner to the toner supplying roller  22  while stirring the toner is provided. The developing unit  20  is rotatably connected to the photosensitive member unit  10  about shafts  27  ( 27 R and  27 L) engageable with holes  26 Rb and  26 Lb provided in the shaft supporting members  26 Rb and  26 Lb. The developing unit  20  is urged by an urging spring  28 . For that reason, during the image formation using the process cartridge  1 , the developing unit  20  rotates about the shafts  27  in the direction indicated by an arrow A, so that the developing roller  21  contacts the photosensitive drum  11 . 
     At a lower portion of the developing unit  20 , a first portion to be urged  30   a  and a second portion to be urged  30   b  which are portion to be urged  30  for receiving an urging force from an urging portion  104 , described later, of the image forming apparatus are provided. 
     These portions to be urged  30  receive an acting force with respect to a direction indicated by an arrow G to rotate the developing unit  20  about the shaft  27  in a direction opposite to the arrow A direction. As a result, the developing roller  21  and the photosensitive drum  11  are kept in a separated state. 
     (Contact and Separation Constitution) 
     Next, with reference to  FIG. 3 , a contact and separation constitution for contacting and separating the developing roller  21  and the photosensitive drum  11  in this embodiment will be described.  FIG. 3  is a schematic view showing the portion to be urged  30 , the urging portion  104 , and their peripheral portions in a state in which the process cartridge  1  is mounted to the image forming apparatus  100 . 
     At a lower portion of the process cartridge  1 , the first portion to be urged  30   a  and the second portion to be urged  30   b  which are the portion to be urged  30  are provided. These first portion to be urged  30   a  and second portion to be urged  30   b  are provided at two longitudinal end portions of the process cartridge  1 . 
     On the other hand, to the image forming apparatus  100 , a developing device contact and separation mechanism  105  actable on the portion to be urged  30  of the process cartridge  1 . The developing device contact and separation mechanism  105  is provided with a guide portion  102  along which the first portion to be urged  30   a  and the second portion to be urged  30   b  slide, during the mounting of the process cartridge  1 , while guiding the first and second portions to be guided  30   a  and  30   b . Further, the guide portion  102  is provided with a first hole  103   a  and a second hole  103   b  at two positions with respect to a longitudinal and mounting direction of the process cartridge  1 . At the bottoms of the first hole  103   a  and the second hole  103   b , a first urging portion  104   a  for urging the first portion to be urged  30   a  and a second urging portion  103   b  for urging the second portion to be urged  30   b  are provided, respectively. The developing device contact and separation mechanism  105  is configured so that the guide portion  102  and the first and second urging portions  104   a  and  104   b  can integrally move with respect to the process cartridge  1  while keeping a mutual positional relationship among the portions  102 ,  104   a  and  104   b . Here, with respect to the mounting direction of the process cartridge  1 , the first portion to be urged  30   a  and the first urging portion  104   a  are provided on an upstream side, and the second portion to be urged  30   b  and the second urging portion  104   b  are provided on a downstream side. 
     Further, the second portion to be urged  30   b  is configured to be larger (longer with respect to the process cartridge  1  mounting direction (indicated by an arrow M in  FIG. 3 ) than the first portion to be urged  30   a . ON the other hand, the first hole  103   a  and second hole  103   b  of the guide portion  102  are formed so as to be larger (longer) than the first portion to be urged  30   a  and the second portion to be urged  30   b , respectively. Further, the second portion to be urged  30   b  is configured to be larger (longer) than the first portion to be urged  30   a.    
     In this embodiment, by forming the portion to be urged  30  in a plate shape, a contact area when the portion to be urged  30  slides on the guide portion  102  is increased, so that a contact (surface) pressure received by the portion to be urged  30  can be reduced. Therefore, it is possible to reduce a degree of wearing (abrasion) of the portion to be urged  30  by the mounting operation of the process cartridge  1 . Further, by providing the portion to be urged  30  at the two longitudinal portions, a variation in separation (spacing) amount in the longitudinal area caused due to torsion deformation of the process cartridge  1 . Further, the first urging portion  104   a  and the second urging portion  104   b  are provided at the bottoms of the first hole  103   a  and the second hole  103   b , so that the guide surface  102   b  of the guide portion  102  is higher than the first and second urging portions  104   a  and  104   b . For this reason, the urging portion  104  is not subjected to sliding caused by mounting and demounting of the process cartridge  1 , so that the urging portion  104  can be prevented from being worn. 
     The first portion to be urged  30   a  and the second portion to be urged  30   b  are configured to be able to enter the first hole  103   a  and the second hole  103   b , respectively. In a state in which the mounting of the process cartridge  1  is completed, the first portion to be urged  30   a  and the second portion to be urged  30   b  contact the first urging portion  104   a  and the second urging portion  104   b  in a state in which the first portion to be urged  30   a  and the second portion to be urged  30   b  have entered the first hole  103   a  and the second hole  103   b.    
     Next, an operation of the developing device contact and separation mechanism  105  will be described with reference to  FIGS. 4(   a ) to  4 ( c ). 
     During the image formation, the developing device contact and separation mechanism  105  receives a driving force from the image forming apparatus  100  and is retracted in a direction indicated by an arrow H. As a result, the force acting on the portion to be urged  30  of the developing unit  20  is released, so that the developing unit is rotated in a direction indicated by an arrow K with the shaft  27  as a supporting point. Then, the developing roller  21  contacts the photosensitive drum  11 , so that a latent image on the surface of the photosensitive drum  11  is developed ( FIG. 4(   a )). 
     When the image forming operation is completed, the developing device contact and separation mechanism  105  moves in a direction indicated by an arrow V to approach the portion to be urged  30  again. In this state, the first and second urging portions  104  ( 104   a ,  104   b ) are configured so that when the portion to be urged  30  of the process cartridge  1  contacts an associated one of the first and second urging portions  104 , the developing roller  21  is moved away from the photosensitive drum  11 . That is, the developing unit  20  is rotated in a direction indicated by an arrow W with the shaft  27  as the supporting point by contact of the portion to be urged  30  with the urging portion  104 . Then, the developing roller  21  is moved away from the photosensitive drum  11  ( FIG. 4(   b )). 
     During the mounting of the process cartridge  1  and during stand-by other than the image formation, the developing device contact and separation mechanism  105  is controlled so as to be stopped at a position in which the developing roller  21  is moved away from the photosensitive drum  11 . 
     On the other hand, the guide surface  102   b  of the guide portion  102  is configured so that the developing roller  21  is moved away from the photosensitive drum  11  when the guide surface  102   b  contacts the portion to be urged  30 . When the process cartridge  1  is mounted and demounted, the developing unit  20  is rotated in a direction indicated by an arrow P with the shaft as the supporting point by contact of the guide surface  102   b  of the guide portion  102  with the portion to be urged  30  of the process cartridge  1 . Then, the developing roller  21  is moved away from the photosensitive drum  11  ( FIG. 4(   c )). 
     Thus, during the mounting operation of the process cartridge  1 , it is possible to move the developing unit  20  away from the photosensitive member unit  10 . Therefore, even in a state in which the process cartridge  1  is left standing for a long time in the image forming apparatus  100 , the developing roller  21  is kept in the separated state with respect to the photosensitive drum  11 . 
     (Mounting of Process Cartridge to Image Forming Apparatus). 
     Next, with reference to  FIGS. 4(   a ) to  4 ( c ) and  FIG. 5 , the mounting operation of the process cartridge  1  to the image forming apparatus  100  will be described. 
     To the image forming apparatus  100 , the process cartridge  1  is mountable with respect to a rotational axis direction (indicated by an arrow F in  FIG. 5 ) of the photosensitive drum  11 . At upper portion and lower portion of the photosensitive member unit  10  of the process cartridge  1 , an upper guide  17  and a lower guide  18  are provided, respectively. On the other hand, to mounting portions  101  ( 101   a - 101   d ), upper mounting rails  106  ( 106   a - 106   d ) for guiding the upper guide  17  and lower mounting rails  107  ( 107   a - 107   d ) are provided. 
     When the process cartridge  1  is mounted to the image forming apparatus  100 , the upper guide  17  and lower guide  18  of the photosensitive member unit  10  are guided and inserted by the upper mounting rail  106  and the lower mounting rail  107 , respectively. 
     Next, with reference to  FIGS. 6(   a ) to  6 ( d ), a contact relationship between the portion to be urged  30  of the developing unit  20  and the developing device contact and separation mechanism  105  of the image forming apparatus  100  during the mounting of the process cartridge  1  will be described. 
     The process cartridge  1  is mounted to the image forming apparatus  100  with respect to a direction indicated by an arrow T shown in  FIGS. 6(   a ) to  6 ( c ). 
     The guide portion  102 , of the image forming apparatus  100 , capable to the portion to be urged  30  of the developing unit  20  is provided with the tapered portion  102   a  on a front side of a mounting direction of the process cartridge  1  ( FIG. 6(   a )). 
     When the process cartridge  1  is inserted into the image forming apparatus  100 , the second portion to be urged  30   b  of the developing unit  20  contacts the tapered portion  102   b . When the process cartridge  1  is inserted further into the image forming apparatus  100 , the second portion to be urged  30   b  is subjected to an acting force, with respect to a direction indicated by an arrow U, along the tapered portion  102   a  to be moved to the guide surface  102   b  ( FIG. 6(   b )). As a result, as described above, the photosensitive drum  11  and the developing roller  21  are placed in the separated state. 
     When the process cartridge  1  is still further inserted into the image forming apparatus  100 , the second portion to be urged  30  is inserted into a position where the first hole  103   a  of the guide portion  102  is provided. At this time, a width L of the second portion to be urged  30   b  is larger than a width N of the first hole  103   a  of the guide portion  102 , so that the second portion to be urged  30   b  passes over the first hole  103   a  along the guide surface  102   b  without entering the first hole  103  ( FIG. 6(   c )). 
     Then, in a state in which the mounting of the process cartridge  1  to the image forming apparatus  100  is completed, the first portion to be urged  30   a  and the second portion to be urged  30   b  are inserted into positions of the first hole  103   a  and the second hole  103   b , respectively. Then, as described above, the developing unit  20  is rotated about the shaft  27  in a contact direction by the urging force of the urging spring  28 , so that the portion to be urged  30  abuts against the urging portion  104  and is held by the urging portion  104  ( FIG. 6(   d )). At this time, the photosensitive drum  11  and the developing roller  21  are separated from each other by the abutment between the portion to be urged  30  and the urging portion  104 . 
     As described above, in the mounting process of the process cartridge  1 , by the constitution in which the second portion to be urged  30   b  is wider than the first hole  103   a , the second portion to be urged  30   b  is non-enterable into the first hole  103   a . Therefore, an insertion load of the process cartridge  1  is not changed during the insertion, so that a mounting property of the process cartridge  1  can be improved. That is, according to this embodiment, during the mounting process of the process cartridge  1  in which the developing roller is movable toward and away from the electrophotographic photosensitive member, a degree of fluctuation in mounting force of the process cartridge can be reduced. As a result, the mounting force of the process cartridge is kept at a constant level, so that the mounting property can be improved. 
     In this embodiment, a length (width) of the process cartridge  1  with respect to the mounting direction of the process cartridge  1  is adjusted but an adjusting method is not limited thereto so long as the second portion to be urged  30   b  is configured so as not to enter the first hole  103   a . That is, a length of the process cartridge  1  with respect to a direction perpendicular to the mounting direction may also be adjusted. 
     Incidentally, in this embodiment, the description is made with respect to the case where the guide portion  102  includes the urging portion  104  (the case where the guide portion  102  is provided integrally with the urging portion  104 ) but the urging portion  104  may also be provided as a separate member. 
     Next, with reference to  FIG. 7 , a developing device contact and separation constitution in this embodiment will be described.  FIG. 7  is a schematic view showing a portion to be urged  230 , a developing device contact and separation mechanism  305 , and their peripheral portions in a state in which the process cartridge  1  is mounted to the image forming apparatus  100 . 
     At a lower portion of the process cartridge  1 , a portion to be guided  202  for being guided by an urging portion  304  of the image forming apparatus  100  described later while sliding on the urging portion  304  is provided. Further, the portion to be guided  202  is provided with a first hole  203   a  and a second hole  203   b  at two portions with respect to the longitudinal and mounting direction of the process cartridge  1 . At the bottoms of the first hole  203   a  and the second hole  203   b , a first portion to be urged  230   a  and a second portion to be urged  230   b  which are the portion to be urged  230  are provided, respectively. 
     On the other hand, to the image forming apparatus  100 , the developing device contact and separation mechanism  305  provided with the urging portion  304  actable on the portion to be urged  302  of the process cartridge  1 . The developing device contact and separation mechanism  305  is provided with a first urging portion  304   a  actable on the first portion to be urged  230   a  and a second urging portion  103   b  for urging the second portion to be urged  30   b  are provided, respectively. The developing device contact and separation mechanism  305  is configured so that the guide portion  102  and the first and second urging portions  204   a  and  204   b  can integrally move with respect to the process cartridge  1  while keeping a mutual positional relationship between the urging portions,  204   a  and  204   b . Here, with respect to the mounting direction of the process cartridge  1 , the first portion to be urged  230   a  and the first urging portion  304   a  are provided on an upstream side, and the second portion to be urged  230   b  and the second urging portion  304   b  are provided on a downstream side. 
     Further, the first urging portion  304   a  is configured to be larger than the first portion to be urged  30   a  with respect to the process cartridge  1  mounting direction (indicated by an arrow M 2  in  FIG. 7 ). On the other hand, the first hole  203   a  and second hole  203   b  of the portion to be guided  202  are formed so as to be longer than the first urging portion  304   a  and the second urging portion  304   b , respectively. Further, the first urging portion  304   a  is configured to be longer than the second hole  203   b . In this embodiment, by providing the portion to be urged  230  at the two longitudinal portions, a variation in separation (spacing) amount in the longitudinal area caused due to torsion deformation of the process cartridge  1 . Further, the first portion to be urged  230   a  and the second portion to be urged  230   b  are provided at the bottoms of the first hole  103   a  and the second hole  203   b , so that a guide surface  202   b  of the portion to be guided  202  is higher than the first and second portions to be urged  230   a  and  230   b . For this reason, the portion to be urged  204  is not subjected to sliding caused by mounting and demounting of the process cartridge  1 , so that the urging portion  104  can be prevented from being worn. 
     The first urging portion  304   a  and the second urging portion  304   b  are configured to be able to enter the first hole  203   a  and the second hole  203   b , respectively. In a state in which the mounting of the process cartridge  1  is completed, the first urging portion  304   a  and the second urging portion  304   b  contact the first portion to be urged  230   a  and the second portion to be urged  230   b  in a state in which the first urging portion  304  and the second urging portion  304   b  have entered the first hole  203   a  and the second hole  203   b.    
     Next, with reference to  FIGS. 8(   a ) to  8 ( d ), a contact relationship between the portion to be urged  230  of the developing unit  20  and the urging portion  304  of the image forming apparatus  100  during the mounting of the process cartridge  1  will be described. 
     The process cartridge  1  is mounted to the image forming apparatus  100  with respect to a direction indicated by an arrow T 2  shown in  FIGS. 8(   a ) to  8 ( c ). 
     The portion to be guided  202 , of the process cartridge  1 , capable to the urging portion  304  of the image forming apparatus  100  is provided with a tapered portion  202   a  on a rear side of a mounting direction of the process cartridge  1  ( FIG. 8(   a )). 
     When the process cartridge  1  is inserted into the image forming apparatus  100 , the tapered portion  202   b  contacts the first urging portion  304   a  of the image forming apparatus  100 . When the process cartridge  1  is inserted further into the image forming apparatus  100 , the portion to be guided  202  of the developing unit  20  is subjected to an acting force, with respect to a direction indicated by an arrow U 2 . As a result, the guide surface  202   b  is moved to a position in which the guide surface  202   b  contacts the first urging portion  304   a  ( FIG. 8(   b )). As a result, as described in Embodiment 1, the photosensitive drum  11  and the developing roller  21  are placed in the separated state. 
     When the process cartridge  1  is still further inserted into the image forming apparatus  100 , the second hole  203   b  of the portion to be guided  202  is inserted into a position of the first urging portion  304   a . At this time, a width L 2  of the second first urging portion  304   a  is larger than a width N 2  of the second hole  203   b  of the portion to be guided  202 , so that the second hole  203   b  passes over the first urging portion  304   a  with no entrance of the first urging portion  304   a  into the second hole  203   b  ( FIG. 8(   c )). 
     Then, in a state in which the mounting of the process cartridge  1  to the image forming apparatus  100  is completed, the first hole  203   a  and the second hole  203   b  are inserted into positions of the first urging portion  304   a  and the second urging portion  304   b , respectively. Then, as described in Embodiment 1, the developing unit  20  is rotated about the shaft  27  in a contact direction by the urging force of the urging spring  28 , so that the portion to be urged  230  abuts against the urging portion  304  and is held by the urging portion  304  ( FIG. 8(   d )). At this time, the photosensitive drum  11  and the developing roller  21  are separated from each other by the abutment between the portion to be urged  230  and the urging portion  304 . 
     As described above, in the mounting process of the process cartridge  1 , by the constitution in which the first urging portion  304   a  is wider than the second hole  203   a , the first urging portion  304   a  is non-enterable into the second hole  203   b . Therefore, an insertion load of the process cartridge  1  is not changed during the insertion, so that a mounting property of the process cartridge  1  can be improved. 
     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 purpose of the improvements or the scope of the following claims. 
     This application claims priority from Japanese Patent Application No. 032821/2009 filed Feb. 16, 2009, which is hereby incorporated by reference.