PATENT ABSTRACT
A developing apparatus usable with an electrophotographic image forming apparatus for forming an image on a recording material, includes a developer carrying member for developing a latent image formed on an electrophotographic photosensitive member with a developer; a first frame for accommodating the developer, the first frame including a first opening for supplying the developer and a first connecting portion provided around first opening; a second frame containing the developer carrying member, a second opening for receiving supply of the developer from the first opening and a second connecting portion provided around the second opening; an elastomer for connecting the first connecting portion and the second connecting portion with each other with the first opening and the second opening being opposed to each other so as to permit movement of the first frame and the second frame and so as to prevent the developer from leaking between the first connecting portion and the second connecting portion.

PATENT DESCRIPTION
FIELD OF THE INVENTION AND RELATED ART 
   The present invention relates to a developing apparatus, a process cartridge, an electrophotographic image forming apparatus, and a method for assembling developing apparatus. 
   Here, an electrophotographic image forming apparatus means an apparatus which forms an image on recording medium (for example, recording paper, OHP sheet, etc.) with the use of an electrophotographic image formation process. As examples of an electrophotographic image forming apparatus, an electrophotographic copying machine, an electrophotographic printer (for example, laser printer, LED printer, etc.), a facsimile machine, a wordprocessor, a multifunction printer, etc., may be included. 
   A process cartridge means a cartridge in which at least a developing means as a processing means, and an electrophotographic photosensitive member, are integrally disposed so that they can be removably mountable in the main assembly of an electrophotographic image forming apparatus. 
   A developing apparatus means an apparatus having a developer storage frame in which developer is stored, a developer bearing member, a developing means frame, which supports the developer bearing member. It is employed by an electrophotographic image forming apparatus. 
   The image forming operation of an electrophotographic image forming apparatus which uses an electrophotographic image formation process is as follows: An electrophotographic photosensitive member, which is in the form of a drum (which hereafter will be referred to simply as photosensitive drum), is uniformly charged by a charging means. Then, numerous points on the charged peripheral surface of the photosensitive drum are selectively exposed in accordance with picture formation information. As a result, an electrophotographic latent is formed on the peripheral surface of the photosensitive drum. This latent image is developed with the combination of a developer bearing member and toner (developer), into an image formed of toner (developer), which hereafter will be referred to as toner (developer) image. Then, the toner image is transferred onto recording medium. Then, the toner image on the recording medium is fixed to the recording medium by applying heat and pressure to the toner image, effecting thereby a permanent toner image on the recording medium. The toner remaining on the peripheral surface of the photosensitive drum after the toner image transfer is removed by a cleaning means so that the cleaned area of the photosensitive drum is used for the subsequent image forming operation. 
   Some process cartridges are made up of a development unit (developing apparatus) and a photosensitive member unit, which are integrally joined. The development unit is made up of a toner storage frame and developing means frame, which are integrally attached to each other. The toner storage frame stores toner, and the developing means frame supports a development roller (developer bearing member). The photosensitive member unit is made up of a photosensitive drum, a charging means, a cleaning means, and cleaning means frame by which the photosensitive drum, charging means, and cleaning means are supported. A process cartridge is made up of the development unit and a photosensitive member unit, which are integrally joined by their developing means frame and cleaning means frame, respectively. 
   In some development units, the developing means frame is movably supported so that it can be moved relative to the toner storage frame (Patent Document 1). More specifically, in these development units, the lengthwise end portions of the development roller are fitted with a pair of spacer rings, one for one. Thus, as the development roller is kept pressed upon the peripheral surface of the photosensitive drum, the pair of spacer rings remain in contact with the peripheral surface of the photosensitive drum  1 , maintaining thereby a preset amount of gap between the peripheral surface of the photosensitive drum and peripheral surface of the development roller. Further, some development units are provided with a foamed polyurethane seal, which is provided for sealing between the developing means frame and toner storage frame to prevent toner from leaking the development units through the joint between the developing means and toner storage frame (Japanese Laid-open Patent Application 2003-76144). 
   However, in order to ensure that the abovementioned joint remains perfectly sealed with the use of the above described prior art, the foamed urethane seal must be compressed by a large amount, making it possible that the amount of the force applied to the developing means frame will become excessive, which in turns will make unnecessarily large the amount of force applied from the development roller to the photosensitive drum. 
   SUMMARY OF THE INVENTION 
   Thus, the primary object of the present invention is to provide a developing apparatus capable of keeping satisfactorily sealed the joint between the first frame which stores developer, and the second frame which supports the developer bearing member, while controlling the amount of force applied from the first frame to the second frame. 
   Another object of the present invention is to provide a process cartridge which is capable of keeping satisfactorily sealed the joint between the first frame which stores developer, and the second frame which supports the developer bearing member, while controlling the amount of force applied from the first frame to the second frame. 
   Another object of the present invention is to provide an electrophotographic image forming apparatus in which the above-described process cartridge is removably mountable. 
   Another object of the present invention is to provide an assemblying method for such a developing apparatus and such a process cartridge. 
   Another object of the present invention is to simplify the method for assembling the above described process cartridge. 
   According to an aspect of the present invention, there is provided a developing apparatus usable with an electrophotographic image forming apparatus for forming an image on a recording material, said developing apparatus comprising a developer carrying member for developing a latent image formed on an electrophotographic photosensitive member with a developer; a first frame for accommodating the developer, said first frame including a first opening for supplying the developer and a first connecting portion provided around first opening; a second frame containing said developer carrying member, a second opening for receiving supply of the developer from said first opening and a second connecting portion provided around said second opening; an elastomer for connecting said first connecting portion and said second connecting portion with each other with said first opening and said second opening being opposed to each other so as to permit movement of said first frame and said second frame and so as to prevent the developer from leaking between said first connecting portion and said second connecting portion. 
   According to another aspect of the present invention, there is provided a developing apparatus usable with an electrophotographic image forming apparatus for forming an image on a recording material, said developing apparatus comprising a developer carrying member for developing a latent image formed on an electrophotographic photosensitive member with a developer; a first frame for accommodating the developer, said first frame including a first opening for supplying the developer and a first connecting portion provided around first opening; a second frame containing said developer carrying member, a second opening for receiving supply of the developer from said first opening and a second connecting portion provided around said second opening; an elastic member in the form of a sheet provided on one of said first connecting portion and said second connecting portion; an elastomer for connecting one of said first connecting portion and said second connecting portion with said elastic member with said first opening and said second opening being opposed to each other so as to permit movement of said first frame and said second frame and so as to prevent the developer from leaking between said first connecting portion and said second connecting portion; an urging member provided on said one of said first connecting portion and said second connecting portion, said urging member urging said elastic member toward a stepped portion of said elastomer. 
   These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view of the development unit in the first embodiment, showing the structural arrangement which allows the developing means frame joined with the developer storage frame to move relative to the developer storage frame. 
       FIG. 2  is a schematic drawing of an example of an electrophotographic image forming apparatus, showing the general structure thereof. 
       FIG. 3  is a schematic drawing of an example of a process cartridge, showing the general structure thereof. 
       FIG. 4  is a schematic drawing showing the structure of the guide of the process cartridge, and the structure of the cartridge guide of the main assembly of the image forming apparatus. 
       FIG. 5  is a perspective view of the photosensitive member unit, developing means frame of the development unit, and side cover, showing their relationship. 
       FIG. 6  is an exploded perspective view of the photosensitive member unit. 
       FIG. 7  is an exploded perspective view of the process cartridge, showing the housing structure thereof. 
       FIG. 8  is an exploded perspective view of the development unit, showing how the development roller and development blade are supported by the developing means frame. 
       FIG. 9  is a schematic drawing showing how the developing means frame is supported by the side cover. 
       FIG. 10  is a schematic drawing showing how the developing means frame is supported by the side cover. 
       FIG. 11  is a perspective view of the developing means frame, as seen from the developer storage frame side. 
       FIG. 12  is a perspective view of the developing means frame and an elastomer dispenser, showing one of the methods for applying elastomer on the developing means frame. 
       FIG. 13  is a perspective view of the developer storage frame, as seen from the developing means frame side. 
       FIG. 14  is a schematic drawing of one of the modified versions of the development unit in the first embodiment. 
       FIG. 15  is a schematic drawing of another of the modified versions of the development unit in the first embodiment. 
       FIG. 16  is a schematic drawing of yet another of the modified versions of the development unit in the first embodiment. 
       FIG. 17  is a schematic drawing of the developing unit, in the second embodiment, prior to the attachment of the toner sealing member to the developer storage frame. 
       FIG. 18  is a schematic drawing of the developing unit, in the second embodiment, after the attachment of the toner sealing member to its developer storage unit. 
       FIG. 19  is a cross-sectional view of the roughly the center of the development unit, in terms of the lengthwise direction of the development unit, in the second embodiment, 
       FIG. 20  is a perspective view of the development unit in the second embodiment prior to the attachment of the elastic sealing member to the developing means frame. 
       FIG. 21  is a perspective view of the development unit in the second embodiment after the attachment of the elastic sealing member to the developing means frame. 
       FIG. 22  is a perspective view of the developing means frame of the development unit in the third embodiment, as seen from the developer storage frame side. 
       FIG. 23  is a perspective view of the developer storage frame of the development unit in the third embodiment, as seen from the developing means frame side. 
       FIG. 24  is a perspective view of the developer storage frame of the development unit in the third embodiment prior to the attachment of the elastic sealing member to the developer storage frame. 
       FIG. 25  is a perspective view of the developer storage frame of the development unit in the third embodiment after the attachment of the elastic sealing member to the developer storage frame. 
       FIG. 26  collectively shows a perspective view and cross-sections of the developer storage frame and developing means frame of the development unit in the third embodiment, which have been joined by their flanges. 
       FIG. 27  is a drawing showing one of the modified versions of the development unit in the third embodiment. 
       FIG. 28  is a drawing including an enlarged section showing another of the modified versions of the development unit in the third embodiment. 
       FIGS. 29(   a ) and  29 ( b ) are schematic sectional views of the development unit shown in  FIG. 28 , the solidified elastomers of the developing means frame and developer storage frame of which have been airtightly placed in contact with each other. 
       FIGS. 30(   a ) through  30 ( g ) are schematic drawings showing an example of the procedure for applying liquid elastomer, in the fourth embodiment. 
       FIGS. 31(   a ),  31 ( b ), and  31 ( c ) are schematic cross-sectional views of another solidified elastomer in the fourth embodiment, showing an elastomer shape different from the one shown in  FIG. 30 . 
       FIG. 32  collectively shows cross-sectional views of the solid elastomers, with which the developer storage frame and developing means frame are provided, showing solid elastomers different in cross section from those shown in  FIGS. 30 and 32 . 
       FIG. 33  is a perspective view including an enlarged section of the developer storage frame and developing means frame of the development unit in the fifth embodiment, which have been joined by their flanges in such a manner that the two frames are movable relative to each other. 
       FIG. 34  is a perspective view of the developing means frame, as seen from the developer storage frame side. 
       FIG. 35  is a perspective view of the developing means frame coated with elastomer, as seen from the developer storage frame side. 
       FIG. 36  is a schematic drawing of the joint between the lengthwise end portion of the solidified elastomer, which corresponds in position to the liquid elastomer application start point, and the lengthwise end of the solidified elastomer, which corresponds in position to the liquid elastomer application end point, on the elastomer support rib of the developer storage frame. 
       FIG. 37  is a perspective view of the developer storage frame, as seen from the developing means frame side. 
       FIG. 38  is a perspective view of the developer storage frame and elastic member prior to the attachment of the elastic member to the developer storage frame. 
       FIG. 39  is a perspective view of the developer storage frame and elastic member after the attachment of the elastic member to the developer storage frame. 
       FIG. 40  is a schematic sectional drawing of the joint between the developer storage frame provided with the elastomer, and developing means frame which is not provided with a rib and the elastic member. 
       FIG. 41  collectively shows a perspective view and cross-sections of the developer storage frame and developing means frame of the development unit, which have been joined by their flanges in such a manner that the two frames are movable relative to each other. 
       FIG. 42  is a perspective view including an enlarged section of the developing means frame joined with the developer storage frame, showing the state of the lengthwise end portion of the solidified elastomer, which corresponds in position to the liquid elastomer application start point, and the lengthwise end of the solidified elastomer, which corresponds in position to the liquid elastomer application end point. 
       FIG. 43  is a schematic cross-sectional view of the joint between the flange of the developer storage frame having a foamed member, instead of the rib, and the flange of the developing means frame having the solidified elastomer. 
       FIG. 44  is a schematic cross-sectional view of the joint between the flange of the developer storage frame having the solidified elastomer instead of the rib, and the flange of the developing means frame having the solidified elastomer. 
       FIG. 45  is a drawing of the development unit in the sixth embodiment, showing its developer storage frame. 
       FIG. 46  is a schematic cross-sectional view of the joint between the developing means frame and developer storage frame of the development unit in the sixth embodiment, showing the relationship among the rib of the developer storage frame, elastic member, and the solidified elastomer of the developing means frame. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereafter, the preferred embodiments of the present invention will be described in detail with reference to the appended drawings. 
   Embodiment 1 
   (1) Structure of Entirety of Electrophotographic Image Forming Apparatus 
     FIG. 2  is a schematic drawing of an example of an electrophotographic image forming apparatus, showing the general structure thereof. This electrophotographic image forming an apparatus (which hereafter will be referred to simply as image forming apparatus) is a laser printer which forms an image on recording medium (for example, recording paper, OHP sheet, fabric, etc.) with the use of an electrophotographic process. 
   In the image forming apparatus, an electrophotographic photosensitive member in the form of a drum  10  (which hereafter will be referred to as a “photosensitive drum”) is rotated in the direction indicated by an arrow mark at a preset peripheral velocity (process speed). The peripheral surface (surface) of the photosensitive drum  10  is uniformly charged by a charging means  11 . The charged area of the peripheral surface of the photosensitive drum  10  is exposed to a beam of laser light L projected from an exposing means  1  (exposing apparatus) while being modulated with picture information. As a result, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum  10 . This electrostatic latent image is developed by the combination of the developing means  13  and toner (developer). As a result, a toner image which reflects the picture information is formed on the peripheral surface of the photosensitive drum  10 . 
   In synchronization with the formation of the toner image, recording mediums P are fed, while being separated one by one, from a feeder cassette  6   a  by a pickup roller  6   b  into the main assembly of the image forming apparatus. Then, each recording medium P is conveyed along a conveyance guide  6   c  to a pair of registration rollers  6   d , which sends the delivered recording medium P to the interface between the photosensitive drum  10  and a transferring means  3 . The transferring means  3  transfers the toner image on the photosensitive drum  10  onto the recording medium P. After the recording medium P receives the toner image, it is conveyed along a conveyance guide  6   e  to a fixing apparatus  5  as a fixing means. 
   The fixing apparatus  5  has a pressure roller  5   c  and a fixation roller  5   b . The fixation roller  5   b  contains a heater  5   a . The recording medium P is conveyed through the nip (fixation nip) between the pressure roller  5   c  and fixation roller  5   b  while remaining pinched by the two rollers  5   c  and  5   b . While the recording medium P is conveyed through the fixation nip, heat and pressure are applied to the recording medium P and the unfixed toner image thereon. As a result, the unfixed toner image is fixed to the surface of the recording medium P. After coming out of the fixing apparatus  5 , the recording medium P is discharged by a discharge toiler  6   f  onto a delivery tray  7 , which is a part of the top surface of the main assembly D of the image forming apparatus. 
   After the transfer of the toner image, the adherent residues on the peripheral surface of the photosensitive drum  10 , such as the toner remaining on the peripheral surface of the photosensitive drum  10  after the toner image transfer, are removed by a cleaning means  14 . Then, the cleaned area of the peripheral surface of the photosensitive drum  10  is used for the subsequent image forming operation. 
   The above-mentioned photosensitive drum  10 , charging means  8 , developing means,  13 , and cleaning means  14  are integrally disposed in a cartridge, making up a process cartridge C, which is removably mountable in the apparatus main assembly D. 
   Designated by a reference numeral  6  is a conveying means for conveying the recording medium P. The conveying means  6  is made up of the pickup roller  6   b , pair of conveyance guides  6   c  and  6   e , registration roller pair  6   d , discharge roller  6   f , etc. 
   (2) Structure of Cartridge C 
   In the following description of the structure of the cartridge C, the “widthwise direction” of the cartridge C or the components thereof means the direction in which the cartridge C is mounted into, or removed from, the apparatus main assembly D, unless specifically noted. Similarly, the “lengthwise direction” means the direction perpendicular (intersectional) to the direction in which the cartridge C is mounted into, or removed from, the apparatus main assembly D. It also means the direction parallel with the axial line of the photosensitive drum  10 . Further, the front surface of the cartridge C means the surface of the cartridge C, which is on the side from which the cartridge C is mounted into, or removed from the apparatus main assembly D. The rear surface of the cartridge C means the opposite surface of the cartridge C from the front surface of the cartridge C. The left- and right-hand sides of the cartridge C means the left- and right-hand sides of the cartridge C as seen from the front side of the cartridge C. The top surface of the cartridge C means the surface of the cartridge C, which is on the top side after the cartridge C is properly positioned in the apparatus main assembly D, and the bottom surface of the cartridge C means the surface of the cartridge C, which is on the bottom side after the cartridge C is properly positioned in the apparatus main assembly D. 
     FIG. 3  is a schematic drawing of an example of the cartridge C, showing the structure thereof.  FIG. 5  is a perspective view of the photosensitive member unit B, developing means frame  51  of the development unit A, and side cover, showing their positional relationship.  FIG. 6  is an exploded perspective view of the photosensitive member unit B. 
   Referring to  FIG. 3 , the development unit A (developing apparatus) is integrally attached to the photosensitive member unit B. The development unit A has a toner storage frame  61  as the first frame, a developing means  13 , and a developing means frame  51  as the second frame. In the toner storage frame  61 , unshown toner is stored. Designated by a reference character  61   a  is an opening ( FIG. 13 ) with which the developer storage frame  61  is provided. It is provided for allowing the toner in the developer storage frame  61  to be supplied for development. The developing means  13  has a pair of toner sending members  23  and  24 , a development roller  20  as a developer bearing member, a development blade  29 , and a blowout prevention sheet  25 . The toner sending members  23  and  24  are rotatably supported by the developer storage frame  61 . The development roller  20  and development blade  29 , and blowout prevention sheet  25  are supported by the developing means frame  51 . The development roller  20  is rotatably supported by the developing means frame  51 , and supplies the latent image formed on the peripheral surface of the photosensitive drum  10 , with toner, by bearing the toner on its peripheral surface (surface). As the toner is supplied to the latent image by the development roller  20 , a visible image is effected on the peripheral surface of the photosensitive drum  10 . The development blade  29  forms a toner layer on the peripheral surface of the development roller  20  while frictionally charging the toner. The blowout prevention member sheet  25  prevents toner from leaking out from the cartridge C through the gap between the bottom side of the development roller  20  and the developing means frame  51 , by sealing the gap. Designated by a reference character  51   a  is the second opening ( FIG. 3 ). The second opening  51   a  is the opening through which the toner supplied from the developer storage frame  61  through the first opening  61   a  is guided to the development roller  20 . This opening  51   a  squarely opposes the first opening  61   a.    
   In the developing means  13 , the toner sending members  23  and  24  rotate in the direction indicated by arrow marks, whereby the toner in the developer storage frame  61  is moved into the developing means frame  51  through the openings  61   a  and  51   a . After being moved into the developing means frame  51 , the toner is borne on the peripheral surface of the development roller  20 , which contains a stationary magnet  28  and is rotating. Then, the toner borne on the peripheral surface of the development roller  20  is formed into a uniform layer of toner with a preset thickness, while being frictionally charged, by a blade  29   e , which is an integrally molded part of the development blade  29 , or bonded to the base portion of the development blade  29 . The development roller  20  is provided with a pair of spacer rings  26   a  and  26   b  ( FIG. 8 ), which are fitted around the lengthwise end portions of the development roller  20 . The development roller  20  is kept pressed toward the peripheral surface of the photosensitive drum  10 , with the presence of the pair of spacer rings  26   a  and  26   b  between the development roller  20  and photosensitive drum  10 . Therefore, a preset amount of clearance is maintained between the peripheral surface of the development roller  20  and the peripheral surface of the photosensitive drum  10 . With the provision of this setup, the toner on the development roller  20  is supplied to the area of the peripheral surface of the photosensitive drum  10 , which is to be developed. As a result, a toner image which reflects the latent image is effected on the peripheral surface of the photosensitive drum  10 . 
   The photosensitive member unit B has a cleaning means frame  12 . The cleaning means frame  12  contains the photosensitive drum  10 , a charge roller  11  as a charging means, and a cleaning blade  14  as a cleaning means, which are supported by the cleaning means frame  12 . More specifically, the photosensitive drum  10  is rotatably supported by the cleaning means frame  12 , with a shaft  15   a  and a pair of bearings  16  interposed between the photosensitive drum  10  and cleaning means frame  12  ( FIG. 5 ). The charge roller  11  is rotatably supported by the cleaning means frame  12  with a pair of bearings  17  and  18  interposed between the charge roller  11  and cleaning means frame  12  ( FIG. 5 ). The cleaning blade  14  is made up of a blade  14   a , which contacts the peripheral surface of the photosensitive drum  10 , and scrapes the residual toner on the peripheral surface of the photosensitive drum  10 , down into a waste toner chamber  12   a.    
   The cartridge C has a top opening  2 , which is the photosensitive drum exposure window located between the cleaning means frame  12  and developing means frame  51 . This top opening  2  allows the peripheral surface of the photosensitive drum  10  to be exposed by the beam of laser light L to form a latent image on the peripheral surface of the photosensitive drum  10 . 
   (3) Structure of Guide of Cartridge C, and Structure of Cartridge Guide of Apparatus Main Assembly D 
   Referring to  FIG. 4 , when mounting the cartridge C into the apparatus main assembly D, a lid  101  is to be rotated upward of the apparatus main assembly D about a shaft  101   a . As the lid  101  is rotated upward, a cartridge slot S in the apparatus main assembly D is exposed. Then, an operator positions the cartridge C so that the cylindrical protrusion  15   a  of a shaft  15 , which protrudes from one of the lengthwise ends of the cleaning means frame  12 , and the cylindrical hollow protrusion  16   a  of a bearing  16 , which protrudes from the other lengthwise end of the cleaning means frame  12 , are supported by positioning guides  102   a  and  102   b , which is in the form of a groove, and with which a pair of side plates of the apparatus main assembly D are provided one for one, and also, so that a pair of cartridge guiding projection  12   a  and  12   b  of the cleaning means frame  12 , which are located above the cylindrical projections  15   a  and  16   a , are fitted in a pair of entrance guides  103   a  and  103   b , one for one, which is in the form of a groove, and with which the abovementioned side plates of the apparatus main assembly D, one for one. Then, the cartridge C is to be inserted into the cartridge slot S from the cleaning means frame  12  side of the cartridge C in the direction parallel with the width direction of the cartridge C. As the cartridge C is inserted, the cylindrical projections  15   a  and  16   a  come into contact with the cartridge positioning surfaces  102   a   1  and  102   b   1  of the positioning guides  102   a  and  102   b , becoming thereby fixed in position; in other words, the cartridge C is set in its image formation position in the apparatus main assembly D. Then, the operator covers the cartridge slot S by rotating the lid  101  toward the apparatus main assembly D about the shaft  101   a.    
   Toward the end of the above-described insertion of the cartridge C into the apparatus main assembly D, an unshown coupling member attached to the lengthwise end of the bearing  16  of the photosensitive drum  10  engages with the coupling member (unshown) of the bearing  16  for the photosensitive drum  10 , which is rotated by a motor (unshown) with which the apparatus main assembly D is provided. As the motor is rotated, not only is the photosensitive drum  10  is rotated by the rotation of the motor, but also, the development roller  20  and developer sending members  23  and  24  are rotated by the rotation of the motor through a gear train (unshown). 
   Further, the electrical contacts (unshown) with which the cartridge C is provided are electrically connected to the electrical contacts (unshown) on the main assembly side. As a result, it becomes possible for a charge bias to be applied to the charge roller  11  of the cartridge C from an electric power source (unshown) of the apparatus main assembly D, and also, for a development bias to be applied to the development roller  20 . 
   When removing the cartridge C from within the apparatus main assembly D, the above-described procedure for mounting the cartridge C is carried out in reverse. 
   (4) Structure of Housing of Cartridge C 
     FIG. 7  is a drawing showing the structure of the housing of the cartridge C. It is an exploded perspective view of the cartridge C, showing the state of the cartridge C prior to its assembly. 
   The cartridge C in this embodiment is a cartridge made up of the development unit A and photosensitive member unit B, which are integrally joined. The developer storage frame  61  and cleaning means frame  12  are precisely positioned relative to each other by first and second side covers  44  and  45 , which are solidly attached to the lengthwise ends of the developer storage frame  61  and cleaning means frame  12 , with the use of fastening means such as screws, resinous bonding, welding, adhesive, etc. The developing means frame  51  is positioned between the developer storage frame  61  and cleaning means frame  12 , and is held by the side covers  44  and  45  so that it is allowed to slide in the direction ar 1 , that is, toward the photosensitive drum  10 , or direction ar 2 , that is, away from the photosensitive drum  10 . 
   (5) Structure of Developing Means Frame  51  of Development Unit A 
     FIG. 8  is an exploded perspective view of the development unit A, showing how the development roller  20  and development blade  29  are supported by the developing means frame  51 .  FIG. 9  is a perspective view of the joint between one of the length wise ends of the development unit A and the side cover  44 , showing how the developing means frame  51  is supported by the side cover  44 .  FIG. 10  is a perspective view of the joint between the other lengthwise end of the development unit A and the side cover  45 , showing how the developing means frame  51  is supported by the side cover  45 . 
   To one of the lengthwise ends of the developing means frame  51 , a first end cover  42  is solidly attached, and to the other lengthwise end of the developing means frame  51 , a second end cover  43  is solidly attached. The end covers  42  and  43  support the development roller  20  and development blade  29  by being solidly attached to the developing means frame  51 . The development roller  20  is rotatably supported by the end covers  42  and  43  with a pair of bearings  27   a  and  27   b  interposed, respectively. The lengthwise end portions of the development roller  20  are fitted with a pair of rings  26   a  and  26   b , the internal diameter of which is slightly larger than the external diameter of the development roller  20 . The rings  26   a  and  26   b  are formed so that the thickness of their walls equals a size of a gap necessary between the photosensitive drum  10  and development roller  20 . The development blade  29  is aligned with a pair of blade positioning bosses  51   b  and  51   c , with which the developing means frame  51  is provided, being thereby precisely positioned, and then, is fastened to the developing means frame  51  with the use of a couple of small screws  95   a  and  95 , respectively. As the development blade  29  is attached to the blade positioning bosses  51   b  and  51   c , the blade proper  29   e  of the development blade  29  is placed in contact with the peripheral surface of the development roller  20 . 
   To the lengthwise end of the development roller  20 , which is on the end cover  42  side, a development roller gear  36  and a development roller gear retaining member  35  are attached. The development roller gear  36  transmits rotational driving force to the development roller  20 . The development roller gear retaining member  35  prevents the development roller gear  36  from disengaging from the development roller  20 , and also, supports the stationary magnet  28 , which is inside the development roller  20 . 
   To the lengthwise ends of the development blade  29 , a pair of toner regulating members  33  and  34  are attached, one for one, which scrape the lengthwise end portions of the peripheral surface of the development roller  20  to guide the toner thereon toward the center of the development roller  20 , in terms of the lengthwise direction of the development roller  20 . 
   Referring to  FIG. 8 , the end covers  42  have flat surfaces  42   a  and  42   b , which are the top and bottom surfaces of the end covers  42 , by which the end cover  42  is supported by the side cover  44  so that it is allowed to slide relative to the side cover  44 . The flat surfaces  42   a  and  42   b  are parallel with each other, and are inclined downwardly toward the photosensitive drum  10 . Further, the end covers  43  have flat surfaces  43   a  and  43   b , which are the top and bottom surfaces of the end covers  43 , by which the end cover  43  is supported by the side cover  45  so that it is allowed to slide relative to the side cover  45 . The flat surfaces  43   a  and  43   b  are parallel with each other, and are inclined downwardly toward the photosensitive drum  10 . Referring to  FIG. 9 , the side cover  44  is provided with a pair of end cover guiding flat surfaces  44   a  and  44   b , which oppose the flat surfaces  42   a  and  42   b . The guiding surfaces  44   a  and  44   b  are parallel with each other and are inclined downwardly toward the photosensitive drum  10 . Further, referring to  FIG. 10 , the side cover  45  is provided with a pair of end cover guiding flat surfaces  45   a  and  45   b , which oppose the flat surfaces  43   a  and  43   b . The guiding surfaces  45   a  and  45   b  are parallel with each other and are inclined downwardly toward the photosensitive drum  10 . That is, the side covers  44  and  45  support the end covers  42  and  43 , with the guiding surfaces  44   a  and  44   b  supporting the flat surfaces  42   a  and  42   b , and guiding surfaces  45   a  and  45   b  supporting the flat surfaces  43   a  and  43   b , respectively ( FIGS. 9 and 10 ). The developing means frame  51 , the lengthwise ends of which are fitted with the end covers  42  and  43 , one for one, is supported by the guiding surfaces  44   a  and  44   b , which guide the end covers  42  and  43  by their flat surfaces  42   a  and  42   b . Therefore, the developing means frame  51  is slidable in the directions ar 1  and ar 2 . That is, the developing means frame  51  is connected to the developer storage frame  61 , with the interposition of the end covers  42  and  43 , so that the developing means frame  51  is movable in the directions ar 1  and ar 2 . 
   Referring to  FIG. 5 , the developing means frame  51  is kept pressed toward the photosensitive member unit B by a pair of springs  32   a  and  32   b  as pressure applying members, which are disposed between the end covers  42  and  43 , and side covers  44  and  44 , respectively. With the provision of the above-described structural arrangement, the development roller  20  is kept pressed toward the photosensitive drum  10 , with a preset clearance kept between the development roller  20  and photosensitive drum  10  by the pair of rings  26   a  and  26   b.    
   (6) Structural Arrangement for Forming A Seal Between Developing Means Frame  51  and Developer Storage Frame  61   
     FIG. 11  is a perspective view of the developing means frame  51 , as seen from the developer storage frame  61  side.  FIG. 12  is a perspective view of the developing means frame  51  and a dispenser  96 , showing an example of the method for applying liquid elastomer  71  to the developing means frame  51 .  FIG. 13  a perspective view of the developer storage frame  61 , as seen from the developing means frame  51  side. 
   Next, the method for assembling the developing means frame  51  and developer storage frame  61  will be described. 
   First, the developing means frame  51  shown in  FIG. 11  is prepared (developing means frame preparation step). The developing means frame  51  has the second opening  51   a , and a flange  51   d  as a second connective portion which surrounds the second opening  51   a . Incidentally, the flange  51   d  does not need to be uniform in structure throughout its entire range around the second opening  51   a ; it may be nonuniform. The flange  51   d  is provided with an elastomer support rib  51   e  to which adhesive liquid elastomer  71  (elastic high-polymer) is applied. The elastomer support rib  51   e  is extended in a manner to surround the opening  51   a , making up a rectangular frame. Referring to  FIG. 12 , the liquid elastomer  71  is applied to the elastomer support rib  51   e  by moving the dispenser  96  along the entirety of the elastomer support rib  51   e  in the direction indicated by an arrow mark, with the use of a numerically-controlled direct action unit. As the dispenser  96  is moved, the heated liquid elastomer  71  is applied to the top surface  51   e   1  of the elastomer support rib  51   e  as indicated by a chain line in the drawing (elastomer application step). Then, the applied elastomer  71  is solidified by cooling. Hereafter, the top surface  51   c   1  of the elastomer support rib  51   e  will be referred to as elastomer application surface  51   e   1 . Further, the solidified elastomer  71  will be referred to simply as elastomer  71 . 
   Next, the developer storage frame  61  shown in  FIG. 13  is prepared (developer storage frame preparation step). The developer storage frame  61  has the first opening  61   a , and a flange  61   b  as the first connective portion which surrounds the first opening  61   a . Incidentally, it is unnecessary for the flange  61   b  to be uniform in structure through its entire range around the opening  61   a , as is the flange  51   d  around the second opening  51   a . The flange  61   b  is positioned so that as the developer storage frame  61  is joined with the developing means frame  51 , it squarely opposes the flange  51   d  of the developing means frame  51 . 
     FIG. 1  is a cross-sectional view of the joint, and its adjacencies, between the developing means frame  51  and developer storage frame  61  joined (connected) so that the two frames are movable relative to each other. 
   Referring to  FIG. 1 , in particular, the enlarged cross-sectional view of the joint E and its adjacencies, the developing means frame  51  and developer storage frame  61  are joined so that the elastomer  71  applied to the developing means frame  51  contacts the surface  61   b   1  of the flange  61   b  of the developer storage frame  61 , so that the interface (contact area) between the elastomer  71  and surface  61   b   1  surrounds the openings  51   a  and  61   a  (frame joining step). As a result, the developing means frame  51  and developer storage frame  61  become connected to each other in such a manner that the two frames are allowed to move relative to each other, while keeping sealed the joint between the flanges  51   d  and  61   b ; toner is prevented from leaking through the joint between the flanges  51   d  and  61   b.    
   The elastomer  71  is high in conformity, and therefore, the amount of pressure which needs to be applied to the elastomer  71  to make the elastomer  71  satisfactorily perform as a sealing member is relatively small. That is, the amount of pressure which needs to be applied to compress the elastomer  71  to seal the joint between the flanges  51   d  and  61   b  is relatively small. Therefore, the reactive force resulting from the pressure applied to the elastomer  71  to seal the joint between the flanges  51   d  and  61   b  is relatively small. In comparison, if foamed polyurethane is used as the material for the sealing member for sealing the joint between the flanges  51   d  and  61   b , the sealing member (foamed polyurethane) must be compressed by a substantially larger amount than the elastomer  71  as a sealing member, in order for the polyurethane to be as effective as the elastomer  71 . Thus, the amount of reactive force generated when the elastomer  71  is used is substantially smaller than that generated when foamed polyurethane is used. Therefore, using the elastomer  71  instead of a sealing member formed of foamed polyurethane can reduce the amount of pressure which is applied to the peripheral surface of the photosensitive drum  10  by the development roller  20  through the rings  26   a  and  26   b  fitted around the lengthwise ends of the development roller  20 , compared to using the sealing member formed of foamed polyurethane alone. That is, this contact pressure (which hereafter will be referred to as pressure D) between the spacer rings  26   a  and  26   b  of the development roller  20 , and the photosensitive drum  10  can be substantially reduced by placing the elastomer  7  to seal the joint between the flanges  51   d  and  61   b , compared to placing a sealing member formed of foamed polyurethane. 
   The reduction in the pressure D reduces the amounts by which the photosensitive drum  10  is frictionally worn, the amount by which the shaft  15  which rotatably supports the photosensitive drum  10  is frictionally worn, and the amount by which the bearing  16  which rotatably supports the photosensitive drum  10  is frictionally worn. Reduction in the pressure D also reduces in the amounts by which the development roller, and the bearings  27   a  and  27   b  which rotatably support the development roller  20 , are frictionally worn. It also reduces the amounts by which the rings  26   a  and  26   b  kept pressed upon the peripheral surface of the photosensitive drum  10  are frictionally worn, and the amounts by which the portions of the peripheral surface of the photosensitive drum  10 , which correspond in position to the rings  26   a  and  26   b , are frictionally worn. Thus, the reduction in the pressure D can extends the lives of the abovementioned components  10 ,  15 ,  16 ,  20 ,  26   a ,  26   b ,  27   a , and  27   b.    
   Moreover, the reduction in the pressure D reduces the amount by which heat is frictionally generated in the contact area between the photosensitive drum  10  and shaft  15 , and the contact area between the photosensitive drum  10  and bearing  16 , as the photosensitive drum  10  is rotated. The reduction in the pressure D also reduces the amount by which heat is frictionally generated in the contact area between the development roller  20  and bearing  27   a , and the contact area between the development roller  20  and bearing  27   b , as the development roller  20  is rotated. Further, it reduces the amount by which heat is generated in the contact area between the photosensitive drum  10  and development roller  20 , the contact area between the peripheral surface of the photosensitive drum  10  and ring  26   a , the contact area between the peripheral surface of the photosensitive drum  10  and ring  26   b , as the photosensitive drum  10  and development roller  20  are rotated. Thus, the reduction in the pressure D makes it possible to reduce the number of fans necessary to be placed in the apparatus main assembly D, making it therefore possible to reduce the amount of electric power consumed by the fans. 
   Further, the reduction in the pressure D reduces the amount by which the development roller  20  is deformed by being kept pressed toward the photosensitive drum  10 . Thus, the reduction in the pressure D makes it less likely for an image, which is nonuniform in density, to be formed due to the deformation of the development roller  20  attributable to the abovementioned contact pressure between the rings  26   a  and  26   b  of the development roller  20  and photosensitive drum  10 ; the reduction in the pressure D can improve the image forming apparatus in image quality. 
   Further, when assembling the development unit A, the developing means frame  51  and developer storage frame  61  can be connected by simply moving the developing means frame  51  and developer storage frame  61  toward each other in a straight line. Therefore, the development unit A is superior to a development unit in accordance with the prior art, in terms of assembly operation efficiency. 
   (7) Modified Version of Development Unit A in Embodiment 1 
   In this embodiment, the top surface  51   e   1  of the developing means frame  51 , to which liquid elastomer  71  is applied, and the surface  61   b   1  of the developer storage frame  61  which the elastomer  71  contacts, are both perfectly flat. However, it is not mandatory that the elastomer application surface  51   e   1 , and the surface  61   b   1  which the elastomer  71  contacts, be perfectly flat. 
     FIG. 14  is a schematic drawing of one of the modified versions of the development unit A in this embodiment. More specifically,  FIG. 14  is a schematic drawing of the joint, and its adjacencies, between the flange  51   d  of the developing means frame  51  and the flange  61   b  of the developer storage frame  61 , showing the state of an airtight contact between the elastomer  71  and the rib  61   b   11  of the developer storage frame  61 . 
   The elastomer application surface  51   e   1  is provided with a groove  51   e   11 , and the surface  61   b   1  is provided with a rib  61   b   11  which the solidified elastomer  71  contacts. In this setup, as the liquid elastomer  71  is applied to the surface  51   b   1 , it flows into the groove  51   c   11 , increasing thereby the contact area between the elastomer  71  and the elastomer application surface  51   e   1 . Therefore, this setup has a greater strength of the bond between the elastomer  71  and elastomer application surface  51   e   1 . Further, in this modification, the elastomer  71  contacts only the top surface of the rib  61   b   11 , instead of directly contacting the surface  61   b   1 . Therefore, this modified version of development unit A in the first embodiment is smaller in the pressure D than the unmodified version of the development unit A in the first embodiment 1. 
     FIG. 15  is a schematic drawing of another modified version of the development unit A in this embodiment. More specifically,  FIG. 15  is a schematic drawing of the joint, and its adjacencies, between the flange  51   d  of the developing means frame  51  and the flange  61   b  of the developer storage frame  61 , showing the state of an airtight contact between the elastomer  71  and the rib  51   d   1  of the developing means frame  51 . 
   The liquid elastomer  71  may be applied to the top surface (which hereafter may be referred to liquid elastomer application surface) of the elastomer support rib  61   e  which projects from the flange  61   b  in a manner to surround the opening  61   a  of the developer storage frame  61 . In this case, the elastomer application surface  61   e   1  may be provided with a groove  61   e   11  so that as the liquid elastomer  71  is applied to the surface  61   b   11 , it flows into the groove  61   e   11 , increasing thereby the contact area between the elastomer  71  and the elastomer application surface  61   e   1 . Therefore, this modified version of the development unit A in the first embodiment has a also greater strength of the bond between the elastomer  71  and elastomer application surface  51   e   1  than the unmodified version of the development unit A in the first embodiment. Further, it is possible to provide the flange  51   d  with a rib  51   d   1 , the top surface of which the elastomer  71  contacts, in order to reduce the pressure D. 
     FIG. 16  is a schematic drawing of yet another modified version of the development unit A in the first embodiment. More specifically,  FIG. 16  is a schematic sectional view of the joint, and its adjacencies, of the flanges  51   d  and  61   b , showing the state of (airtight) contact between the elastomer  72  attached to the developing means frame  51 , and the elastomer  73  attached to the developer storage frame  61 . 
   In this modified version of the development unit A in this embodiment, liquid elastomers ( 72 ) and ( 73 ) are applied to the elastomer application surface  51   e   1  of the elastomer support rib  51   e , and the elastomer application surface  61   e   1  of the elastomer support rib  61   e , respectively (elastomer application step). That is, the liquid elastomer is applied to the elastomer application surfaces  51   e   1  and  61   e   1  so that solidified elastomers  72  and  73  are formed on the elastomer application surfaces  51   e   1  and  61   e   1 , respectively. Then, the developing means frame  51  and developer storage frame  61  are joined so that the two elastomers  72  and  73  are in airtight contact with each other (elastomer contact step). Therefore, this modified version of the development unit A is smaller in the amount of reactive force generated as the developing means frame  51  and developer storage frame  61  are joined and attributable to the resiliency of the solidified elastomer (elastomers  72  and  73 ) than the preceding modified version, which is smaller in the above-mentioned reactive force than the unmodified version of the development unit A in this embodiment; this modified version of the development unit A is much more smaller in the pressure D than those shown in  FIGS. 14 and 15 . Incidentally, a sealing member formed of foamed polyurethane or the like, which is elastic, may be adhered to one of the abovementioned frames so that the elastomer is in airtight contact with this sealing member formed of foamed polyurethane. Such an arrangement also can reduce the amount of the reactive force. 
   In this embodiment, the elastomers  71 ,  72 , and  73  are formed by solidifying liquid elastomer by cooling. However, the method for solidifying liquid elastomer does not need to be limited to cooling. For example, instead of the liquid elastomer used in this embodiment, such liquid elastomer that solidifies as it is mixed with a specific liquid may be employed as the material for the elastomers  71 ,  72 , or  73 . Such liquid elastomer can also be used as the material for the elastomers in the second, third, and fourth preferred embodiments of the present invention, which will be described below. 
   Embodiment 2 
   Next, the development unit in another embodiment of the present invention will be described. 
   The components in this embodiment, which are identical to those in the first embodiment will be given the same reference numerals and characters as those given to the counterparts in the first embodiment, and will not be described in order not to repeat the same descriptions. Like the development unit A in the first embodiment, the development unit A in this embodiment also is integrally joined with the photosensitive member unit B to make up the cartridge C, and so is the cartridge C in the third embodiment. 
     FIG. 17  is a drawing of the developer storage frame  61  and a developer storage frame sealing member  19  (which hereafter will be referred to simply as sealing member) before the sealing member  19  is attached to the developer storage frame  61 .  FIG. 18  is a drawing of the developer storage frame  61  and a developer storage frame sealing member  19  after the sealing member  19  is attached to the developer storage frame  61 .  FIG. 19  is a cross-sectional view of the roughly center portion of the development unit A, in terms of the lengthwise direction of the development unit A.  FIG. 20  is a drawing of the developing means frame  51  and an elastic sealing member  21  before the elastic sealing member  21  is attached to the developing means frame  51 .  FIG. 21  is a drawing of the developing means frame  51  and an elastic sealing member  21  after the elastic sealing member  21  is attached to the developing means frame  51 . 
   In order to prevent the toner in the development unit A of the cartridge C from leaking during the distribution of the cartridge C, the opening  61   a  of the developer storage frame  61  is sealed by thermally welding the edge portions of the sealing portion  19   a  of the sealing member  19  to the flange  61   b  of the developer storage frame  61 , or adhering the edge portions of the sealing portion  19   a  of the sealing member  19  to the flange  61   b  of the developer storage frame  61  with the use of two-sided adhesive tape, or the like bonding means ( FIGS. 17 and 18 ). The sealing member  19  is positioned so that the edge portions of the sealing portion  19   a  is placed between the opening  61   a  and rib  61   b   11  of the developer storage frame  61 . Further, the longer edge portions  19   a   1  and  19   a   2  of the sealing portion  19   a  of the sealing member  19  and the shorter edge portion  19   a   3  of the sealing portion  19   a  of the sealing member  19  are adhered to the surface  61   b   1  ( FIG. 18 ). The extension portion  19   b  of the sealing member  19 , which extends from the sealing portion  19   a , is folded back at the lengthwise end  61   b   2  of the flange  61   b , is overlaid on the sealing portion  19   a  across the entire length of the sealing portion  19   a , from the lengthwise end  61   b   2  to the lengthwise end  61   b   3 , that is, the other lengthwise end of the flange  61   b , and is extended outward of the development unit A through the gap provided between the corresponding ends of the flanges  61   b  and  51   d  of the developer storage frame  61  and developing means frame  51 , respectively ( FIG. 19 ). To the outward end of the extension portion  19   b , a tab  19   c  which a user grasps when pulling out the sealing member  19  is attached. 
   Referring to  FIGS. 21 and 22 , the developing means frame  51  is provided with an elastic sealing member  21 , which is adhered to the lengthwise end  51   d   3  of the developing means frame  51 , with the use of two-sided adhesive tape. The elastic sealing member  21  is formed of polyurethane or the like. The area of the elastic sealing member  21 , which comes into contact with the sealing member  19 , is coated with a specific member  21   a . This member  21   a  is very high in the slipperiness relative to the sealing member  19 . Referring to  FIG. 19 , the elastic sealing member  21  adhered to the developing means frame  51  remains compressed between the developing means frame  51  and the lengthwise end portion  61   b   3  of the developer storage frame  61 . Thus, the elastic sealing member  21 , along with the extension portion  19   b  of the sealing member  19 , keeps sealed the gap between the developing means frame  51  and developer storage frame  61 , through which the extension portion  19   b  of the sealing member  19  is placed. Therefore, the toner in the development unit A is prevented from leaking during the distribution of the cartridge C. 
   The sealing member  19  is to be pulled out by a user before the cartridge C is mounted into the apparatus main assembly D. As the sealing member  19  is pulled out, the openings  61   a  and  51   a  become connected, making it possible for the toner in the developer storage frame  61  to be supplied to the development roller  20  in the developing means frame  51  through the opening  61   a  and  51   a.    
   Referring to  FIG. 20 , the flange  51   d  is provided with the rib  51   e  as an elastomer support, which extends in a manner to surround the opening  51   a , except for the lengthwise end portion  51   d   3  to which the elastic sealing member  21  is adhered. To this elastomer support  51   e , the liquid elastomer  71  is applied. The elastomer application surface  51   e   1  of the elastomer support  51   e  is provided with a groove  51   c   11  as is the elastomer application surface  51   e   1  in the first embodiment. The elastic sealing member  21  is adhered to the lengthwise end portion  51   d   3 , with the surface  21   b  of the elastic sealing member  21  placed in contact with the end surfaces  51   d   21  and  51   e   31  of the lengthwise ends  51   e   2  and  51   e   3 , respectively, of the sealing member  21 . Next, referring to  FIG. 21 , the liquid elastomer  71  is applied to the elastomer application surface  51   e   1 , using the dispenser  96  ( FIG. 12 ). At the same time, liquid elastomer is applied to the lengthwise ends  51   e   2  and  51   e   3  of the elastomer support rib  51   e  to ensure that there will be no gap between the surface  21   b  of the elastic member  21  and the lengthwise ends  51   e   2  and  52   e   3 . Then, the liquid elastomer  71  is solidified by cooling; the liquid elastomer  71  is turned into the elastomer  71 . 
   Referring to  FIG. 18 , the surface  61   b   1  of the flange  61  is provided with the rib  61   b   11 , which corresponds in position to the elastomer  71 . 
   Referring to  FIG. 19 , as the developing means frame  51  and developer storage frame  61  are joined so that they are allowed to move relative to each other, the elastomer  71  of the developing means frame  51  comes into contact with the end surface of the rib  61   b   11 , sealing thereby between the flanges  51  and  61 , except for the area which corresponds in position to the elastic sealing member  21 . Therefore, it is possible to prevent the toner in the development unit A from leaking through the joint between the flanges  51  and  61 , except through the area corresponding to the elastic sealing member  21 . 
   According to this embodiment, even in the case of a development unit A provided with the toner sealing member  19 , the same functions and operations as those obtained in the first embodiment can be obtained by widening, as much as possible, the range which the elastomer  71  seals. 
   Embodiment 3 
   Next, the development unit in another embodiment of the present invention will be described. 
     FIG. 22  is a perspective view of the developing means frame  51  as seen from the developer storage frame  61  side.  FIG. 23  is a perspective view of the developer storage frame  61  as seen from the developing means frame  51  side.  FIG. 24  is a perspective view of the developer storage frame  61  prior to the attachment of the elastic sealing members  81 ,  82 ,  83 , and  84  to the developer storage frame  61 .  FIG. 25  is a perspective view of the developer storage frame  61  after the attachment of the elastic sealing members  81 ,  82 ,  83 , and  84  to the developer storage frame  61 .  FIG. 26  is a perspective view of the developing means frame  51  and developer storage frame  61 , which have been joined by their flanges  51   d  and  61   b.    
   Referring to  FIG. 22 , the flange  51   d  is provided with an elastomer support rib  51   e  to which liquid elastomer  71  is applied. The elastomer support rib  51   e  extends in a manner to surround the opening  51   a . The elastomer application surface  51   e   1  of the elastomer support rib  51   e  is provided with a groove  51   e   11  as is the elastomer application surface  51   e   1  in the first embodiment. Referring to  FIG. 26 , the liquid elastomer  71  is applied to the elastomer application surface  51   e   1  using the dispenser  96  ( FIG. 12 ) (elastomer application step). Then, the liquid elastomer  71  is solidified by cooling. 
   Referring to  FIG. 23 , the four corners of the flange  61   b  of the developer storage frame  61  have four grooves  61   g   1 ,  61   g   2 ,  61   g   3 , and  61   g   4 , which correspond in position to the outward areas of the four corners (corner areas)  61   b   5 ,  61   b   6 ,  61   b   7 , and  61   b   8  of the opening  61   a . The grooves  61   g   1 ,  61   g   2 ,  61   g   3 , and  61   g   4  are positioned so that their positions coincide with the portions of the elastomer  71 , which are on the outward areas of the four corners (corner areas) of the opening  51   a  of the developing means frame  51 . Further, the grooves  61   g   1 ,  61   g   2 ,  61   g   3 , and  61   g   4  are surrounded by ribs  61   h   1 ,  61   h   2 ,  61   h   3 , and  61   h   4 , which protrude toward the developing means frame  51 . 
   The straight edge portions of the flange  61   b  of the developer storage frame  61 , that is, the edge portions other than the abovementioned portions which correspond in position to the four corners of the opening  61   a , are provided with ribs  61   f   1 ,  61   f   2 ,  61   f   3 , and  61   f   4 , which are positioned so that they are on the outward side of the portions of the elastomer  71 , which are formed on the straight edge portions of the flange  51   d , that is, the edge portions other than the edge portions which correspond in position to the four corners of the opening  51   a . The  61   f   1 ,  61   f   2 ,  61   f   3 , and  61   f   4  protrude by a height greater than the height by which the ribs  61   h   1 ,  61   h   2 ,  61   h   3 , and  61   h   4  protrude. 
   Referring to  FIGS. 24 and 25 , the elastic members  81 ,  82 ,  83 , and  84  are attached to the top surfaces of the ribs  61   f   1 ,  61   f   2 ,  61   f   3 , and  61   f   4 , respectively (elastic member attachment step). As for the examples of the means for attaching the elastic members  81 ,  82 ,  83 , and  84 , they may be attached using two-sided adhesive tape, or may be thermally welded. The elastic members  81 ,  82 ,  83 , and  84  are in the form of a sheet, and are formed of metal or resin. 
   Into the grooves  61   g   1 ,  61   g   2 ,  61   g   3 , and  61   g   4 , liquid elastomer  71  is injected using the dispenser  96  ( FIG. 12 ) ( FIGS. 24 and 25 ), by such an amount that the body of the injected liquid elastomer  71  protrudes slightly higher than the elastic members  81 ,  82 ,  83 , and  84 , and also, that it airtightly fills the gaps between the adjacent two elastic members among the elastic members  81 ,  82 ,  83 , and  84 . Then, the liquid elastomer  71  is solidified by cooling. 
   Referring to  FIG. 26 , the developing means frame  51  and developer storage frame  61  are joined by their flanges  51   d  and  61   b . That is, the portions of the elastomer  71 , which correspond in position to the straight edges of the flanges  51   d  and  61   b  (enlarged cross-sectional view at line F-F), are placed in airtight contact with the third sealing areas, that is, the free edge portions  81   a ,  82   a ,  83   a , and  84   a  (opposite portions from portions by which elastic members are attached to developer storage frame  61 ) of the elastic members  81 ,  82 ,  83 , and  84  (elastic member contact step). In this step, at the corners of the flanges  51   d  and  61   b  (enlarged cross-sectional view at line G-G), the elastomers  71  and  74 , with which the developing means frame  51  and developer storage frame  61  are provided, respectively, come into airtight contact with each other. Thus, the developing means frame  51  and developer storage frame  61  are joined by the flanges  51   d  and  61   b , with the joint between the developing means frame  51  and developer storage frame  61  sealed by the elastic members  81 ,  82 ,  83 , and  84 , and elastomers  71  and  74  so that the toner does not leak. 
   This embodiment makes it possible to keep the pressure D low, even if the amount by which the elastomers  71  and  74  need to be compressed increases due to the variations in the measurements of the developing means frame  51  and/or developer storage frame  61 . That is, the provision of the elastic members  81 ,  82 ,  83 , and  84  in the form of a sheet reduces the effects which the variations in the measurements of the developing means frame  51  and/or developer storage frame  61  have on the reactive force generated in the elastomers  71  and  74 . Therefore, the pressure D is kept small. 
   In this embodiment, the elastomer  71  is placed on the elastomer support rib  51   e . Instead, however, the elastomer  71  may be placed on the top surfaces (surfaces on developer means frame  51  side) of the third contact areas  81   a ,  82   a ,  83   a , and  83   d  of the elastic members  81 ,  82 ,  83 , and  84 , respectively, attached to the developer storage frame  61 . In such a case, the elastomer  71  placed on the third contact areas  81   a ,  82   a ,  83   a , and  84   a  is in airtight contact with the elastomer application surface  51   e   1  of the elastomer support rib  51   e  (cross-sectional view at F-F). 
   Also in this embodiment, not only is the elastomer  71  placed on the elastomer support rib  51   e , but also, the elastomer  74  is placed on the corner areas of the flange  61   d . In addition, the elastic members  81 ,  82 ,  83 , and  84  are attached to the straight edges portions of the flange  61 . Instead, however, the elastomer  71  may be attached to the developer storage frame  61  by providing the developer storage frame  61  with an elastomer support rib, whereas the elastic members  81 ,  82 ,  83 , and  84  may be attached to the straight edge portions of the flange  51 . 
   Further, the elastic members  81 ,  82 ,  83 , and  84  may be integrally formed with the developer storage frame  61  or developing means frame  51 . 
     FIG. 27  is a drawing of a modified version of the development unit A in this embodiment. More specifically,  FIG. 27  is a cross-sectional view of the joint between the flanges  51   d  and  61   b  of the developing means frame  51  and developer storage frame  61 , respectively, showing the state of the airtight contact between the elastomer  71  and each of the third contact areas  81   a ,  82   a ,  83   a , and  84   a.    
   In this modification, the developing means frame  51  and developer storage frame  61  are designed so that even after the developing means frame  51  and developer storage frame  61  are joined so that they are allowed to move relative to each other, and the third contact areas  81   a ,  82   a ,  83   a , and  84   a  make airtight contact with the elastomer  71 , a gap H will be present between the surface  61   b   1  of the developer storage frame  61  and each of the elastic members  81 ,  82 ,  83 , and  84 . 
   In the modified version of the development unit A in this embodiment, the third contact areas  81   a ,  82   a ,  83   a , and  84   a  do not make contact with the surface  61   b   1  of the developer storage frame  61 . Therefore, the reactive force generated in the elastomer  71  in this modified version is smaller than that in the unmodified version of this embodiment, and therefore, the pressure D in this modified version is smaller than that in the unmodified version in this embodiment. 
     FIGS. 28 and 29  are drawings of the modified version of the development unit A in this embodiment.  FIG. 28  is a perspective view of the developing means frame  51  as seen from the developer storage frame  61  side.  FIG. 29  collectively shows cross-sectional views of the joint between the developing means frame  51  and developer storage frame  61 , showing the state of contact between the elastomers  71  and  75 , in the gap between the developing means frame  51  and developer storage frame  61 . In  FIG. 29 ,  FIG. 29(   a ) is an enlarged cross-sectional view of the joint between the developing means frame  51  and developer storage frame  61 , at a plane corresponding to the line F-F in  FIG. 26 , and  FIG. 29(   b ) is an enlarged cross-sectional view of the joint between the developing means frame  51  and developer storage frame  61 , at a plane corresponding to the line G-G in  FIG. 26 . 
   In this modified version of the development unit A, the developer storage frame  61  is provided with an elastomer  75 , which is formed in a manner to encircle the opening  61   a  and cover the third contact areas  81   a ,  82   a ,  83   a , and  84   a  and the top surface (surface on developing means frame  51  side) of the elastomer  74  attached to the corner portions of the flange  61   b.    
   That is, liquid elastomer  71  is applied to the third contact areas  81   a ,  82   a ,  83   a , and  84   a , and the top surfaces of the solidified elastomers  74  located at the four corners, one for one, of the flange  61 , using the dispenser  96  ( FIG. 12 ). As the liquid elastomer  71  solidifies, it turns into the elastomer  75  as described above. Thereafter, the developing means frame  51  and developer storage frame  61  are joined by the flanges  51   d  and  61   b . As the two frames  51  and  61  are joined, the elastomers  75  and  71  airtightly contact with each other ( FIGS. 29(   a ) and  29 ( b )). 
   In this modified version of the development unit A in this embodiment, the elastomers  71  and  75  attached to the flanges  51   d  and  61   b  of the developing means frame  51  and developer storage frame  61 , respectively, are made to airtightly contact with each other. Therefore, this modified version of the development unit A is far smaller in the amount of the reactive force generated by the elastomers. Therefore, it is far smaller in the amount of the pressure D. 
   Embodiment 4 
   Next, the method for applying liquid elastomer will be described. 
   In this embodiment, the method for applying the liquid elastomer  71  will be described. This method can also be used for applying the liquid elastomer other than the liquid elastomer  71 , that is, the liquid elastomers  72 ,  73 ,  74 , and  75 . 
     FIGS. 30(   a )- 30 ( g ) are schematic drawings showing one of the procedures for applying the liquid elastomer  71 . 
   First, a pair of liquid elastomer application assist plates  101  and  102  ( FIG. 30(   b )) are set up so that they are placed airtight in contact with the lateral surfaces  51   e   2  and  51   e   3  of the elastomer support rib  51   e   1  ( FIG. 30  ( a )). The assist plate  101 , which is on the opening  51   a  side of the elastomer support rib  51   e , is the same in length as the elastomer support rib  51   e , and has an elastomer application assist surface  101   a , which extends straight toward the developer storage frame  61  as if it were an extension of the lateral surface  51   e   2  of the elastomer support rib  51   e.    
   The liquid elastomer application assist plate  102 , which is placed on the opposite side of the elastomer support rib  51   e  from the opening  51   a , is provided with a liquid elastomer application assist surface  102   a , which is made up of two surfaces. One of the surfaces is level with the liquid elastomer application surface  51   e   1 , and is on the opposite side of the liquid elastomer application surface  51   e   1  from the opening  51   a , whereas the other surface is parallel to the lateral surface  51   e   3  and extends straight toward the developer storage frame  61 . The dispenser  96  is moved all the way along the top edges of the liquid elastomer application assist plates  101  and  102 , while being kept right above the space  103  surrounded by the elastomer support rib  51   e , and elastomer application assist surfaces  101   a  and  102   a , in a manner to coat the top surface  51   e   1  of the elastomer support rib  51   e  with the liquid elastomer  71  (liquid elastomer application step). As a result, the space  103  is filled with the liquid elastomer  71  ( FIG. 30(   c )). After the solidification of the liquid elastomer  71 , the liquid elastomer application assist plates  101  and  102  are separated from the elastomer support rib  51   e  by being moved in the direction roughly parallel to the liquid elastomer application surface  51   e   1  ( FIG. 30(   d )), ending thereby the liquid elastomer application step. The reason why the liquid elastomer application assist plates  101  and  102  are separated in the direction roughly parallel with the liquid elastomer application surface  51   e   1  is to minimize the amount of the force which acts in the direction to dislodge the coated and solidified elastomer  71  from the elastomer support rib  51   e  when the plates  101  and  102  are moved away from the elastomer  71 . The elastomer  71  remains adhered to the liquid elastomer application surface  51   e   1  of the elastomer support rib  51   e  by its own adhesiveness. As the liquid elastomer application assist plates  101  and  102  are moved away, the elastomer  71  emerges, the lateral surface  51   e   2  side of which is level with the lateral surface  51   e   2 , whereas the lateral surface  51   e   3  of which extends beyond the lateral surface  51   e   3 ; the elastomer  71  has a protrusion  71   a  ( FIG. 30(   e )). In other words, the protrusion  71   a  protrudes in the direction intersectional to the circumference of the flange  51   d . This intersectional direction is the left-right direction of  FIG. 30 , as seen from the direction perpendicular to the sheet of paper on which  FIG. 30  is drawn. Further, the protrusion  71   a  is not in contact with the liquid elastomer application surface  51   e   1 . 
   The developer storage frame  61  has a rib  61   b   1 , which perpendicularly projects from the flange  61   b . The rib  61   b   1  is where the elastomer  71  contacts to airtightly seal the development unit A. The rib  61   b   1  corresponds in position to the protrusion  71   a  ( FIG. 30(   f )). The rib  61   b   1  is positioned so that even if it is extended in the direction (indicated by double-dot chain lines PH 1  and PH 2 ) parallel with the directions ar 1  and ar 2  in which the developing means frame  51  is movable, it does not overlap with the elastomer support rib  51   e . That is, in terms of the abovementioned intersectional direction, the point at which the elastomer  71  is in contact with the flange  61   b  is different from the point at which the elastomer  71  is in contact with the flange  51   d . Further, when the developing means frame  51  and developer storage frame  61  are in contact with each other by the flanges  51   d  and  61   b , respectively, the elastomer  71  is in contact with the rib  61   b   1 , remaining in the state in which the elastomer  71  may be said be compressed by the rib  61   b   1 . When the elastomer  71  is in this state, reactive force is generated in the protrusion  71   a  by the compression. However, there is nothing to back up the protrusion  71   a  on the side (developing means frame  51  side) toward which the protrusion  71   a  deforms by being pressed by the rib  61   b   1 . Therefore, this reactive force is smaller than the reactive force which the elastomer  71  would have generated, if the protrusion  71   a  were backed up. In other words, this modified version of the development unit A is smaller in the value of “amount of reactive force/amount of compression” than the unmodified version of the development unit A in this embodiment. 
   The elastomer  71  is high in conformance. Therefore, it is small in the amount of compressive force necessary to be applied thereto to make it serve as an effective sealing member. In addition, this modified version of the development unit A in this embodiment is small in the amount of variation of the reactive force resulting from the variation in the amount of the compressive force. Therefore, it is smaller in the amount of the reactive force generated by the elastomer  71 , being therefore smaller in the amount of the pressure D. 
   In this embodiment, the elastomer  71  formed by solidifying the liquid elastomer  71  after its application was rectangular in cross section. However, it is not mandatory that the elastomer  71  is rectangular in cross section.  FIGS. 31 ,  32 ( b ) and  32 ( c ) show another shape that is acceptable as the cross-sectional shape for the elastomer  71 . 
     FIG. 31(   a ) shows the first of the shapes acceptable as the cross-sectional shape for the elastomer  71 . In this case, the surface  102   a  of the liquid elastomer application assist plate  102  is concavely curved so that its farthest end portion from the elastomer support rib  51   e  is roughly parallel with the lateral surfaces of the elastomer support rib  51   e . That is, a liquid elastomer application assist plate  102  having the liquid elastomer application assist surface  102   a  shown in  FIG. 31(   a ) may be used to apply liquid elastomer to the elastomer support rib  51   e  to form a protrusion  71   a , shown in  FIG. 31(   b ), which convexly curves, in terms of cross section, across the surface which connects the top and bottom surfaces. Therefore, the amount of the deformation ( FIG. 31(   c )) which occurs to this protrusion  71   a  as it is pressed by the rib  61   b   1  is smaller that which occurs to the protrusion  71   a  in the preceding modified version of the development unit A, being therefore smaller in the value of “amount of reactive force/amount of compressive force” than the protrusion  71   a  in the preceding modified version of the development unit A. Therefore, it is far smaller in the amount of the variation of the reactive force attributable to the variation in the amount of the compressive force. Further, it is smaller in the amount of the resistance which the liquid elastomer application assist plate  102  is subjected when it is separated from the solidified elastomer  71  (protrusion  71   a ). 
     FIGS. 32(   a ) and  32 ( c ) are schematic drawings showing another example of the shape usable as the cross-sectional shape for the elastomers  72  and  73 . 
   Referring to  FIG. 32(   a ), the liquid elastomer  72  is applied to the flange  51   d  (liquid elastomer application step). The resultant solid elastomer  72  has a protrusion  72   a , which extends beyond the edge of the liquid elastomer application surface  51   e   1  of the elastomer support rib  51   e , on the lateral surface  51   e   2  side. Further, the liquid elastomer  73  is applied to the flange  61   b  (liquid elastomer application step). The resultant solid elastomer  73  has a protrusion  73   a , which extends beyond the edge of the liquid elastomer application surface  61   e   1  of the elastomer support rib  61   e , on the lateral surface  61   e   2  side. In other words, the protrusion  73   a  protrudes in the direction which is intersectional to the direction of the periphery of the flange  61   b . This intersectional direction is the left-right direction of  FIG. 32 , as seen from the direction perpendicular to the sheet of paper on which  FIG. 32  is drawn. These protrusions  72   a  and  73   a  are positioned so that even if they are extended in the direction parallel with the directions ar 1  and ar 2  (indicated by double-dot chain lines PH 1  and PH 2  in  FIG. 32(   a )) in which the developing means frame  51  is movable, they will not overlap with the elastomer support ribs  61   e  and  51   e , respectively. That is, the protrusions  72   a  and  73   a  are positioned so that they do not align with the liquid elastomer application surfaces  61   e   1  and  51   e   1  of the elastomer support ribs  61   e  and  51   e , respectively. In other words, in terms of the abovementioned intersectional direction, the location of the interface (bonding) between the elastomer  72  and flange  51   d  is different from the location of the interface (bonding) between the elastomer  73  and flange  61   b . Further, the protrusions  72   a  and  73   a  are formed so that they do not come into contact with either of the developing means frame  51  and developer storage frame  61 . The developing means frame  51  and developer storage frame  61  are joined by the flanges  51   d  and  61   b . As the developing means frame  51  and developer storage frame  61  are joined, the protrusions  72   a  and  73   a  of the elastomers  72  and  73 , respectively, come into contact with each other (elastomer contact step). After the occurrence of the contact between the elastomers  72  and  73 , the elastomers  72  and  73  is kept in airtight contact with each other, being therefore compressed by each other. Therefore, this compression generates reactive force in the protrusions  72   a  and  73 . However, neither the protrusion  72   a  nor the protrusion  73   a  are backed up from the sides toward which they deform (developing means frame  51  side and developer storage frame  61  side, respectively). In other words, what occurs here is that two elastic members compress each other. Therefore, the value of “amount of reactive force/amount of compressive force” in this modified version of this embodiment is even smaller than that in the preceding modified versions of this embodiment. Therefore, this modified versions is even smaller in the amount of variation in the amount of the reactive force attributable to the variation in the amount of the compressive force, being therefore smaller in the amount of the pressure D. 
   Embodiment 5 
   In terms of image forming apparatus structure, this embodiment is similar to the first embodiment described above. Therefore, only the differences of this embodiment from the first embodiment will be described. 
   (1) Structure of Sealing Means Between Developing Means Frame  51  and Developer Storage Frame  61   
     FIG. 33  is a cross-sectional view of the developing means frame  51  and developer storage frame  61  joined by their flanges so that they are movable relative to each other.  FIG. 34  is a perspective view of the developing means frame  51  as seen from the developer storage frame  61  side.  FIG. 35  is a perspective view of the developing means frame  51  provided (coated) with the elastomer  71 , as seen from the developer storage frame  61  side. 
   Next, the method for assembling the developing means frame  51  and developer storage frame  61  will be described. 
   First, the developing means frame  51  shown in  FIG. 34  is prepared (developing means frame preparation step). The developing means frame  51  has the second opening  51   a , and a flange  51   d  as the second connective portion which surrounds the second opening  51   a . Incidentally, the flange  51   d  does not need to be uniform in structure throughout its entire range around the second opening  51   a , as did not the flange  51  in the first embodiment. The flange  51   d  is provided with an elastomer support rib  51   e  to which adhesive liquid elastomer  71  (elastic high-polymer) is applied. The elastomer support rib  51   e  is extended in a manner to surround the opening  51   a , forming a rectangular frame. The elastomer supporting rib  51   e  is rendered flat at the top, to provide the elastomer support rib  51   e  with a surface to which liquid elastomer  71  is applicable. The top surface  51   e   1  of the elastomer support rib  51   e  is provided with a groove  51   e   11 , which extends in a manner to surround the opening  51   a . Further, the flange  51   d  is provided with a connective portion  51   e   12  where the lengthwise end of the elastomer  71 , which corresponds in position to the point at which the application of liquid elastomer  71  is started, and the other lengthwise end of the elastomer  71 , which corresponds in position to the point at which the application of the liquid elastomer  71  is ended, are connected to each other. The connective portion  51   e   12  is rendered wider than the top surface  51   e   1 . 
   Referring to  FIG. 12 , the dispenser  96  is moved along the entirely of the elastomer support rib  51   e  in the direction indicated by an arrow mark, starting from the connective portion  51   e   12 . As the dispenser  96  is moved, the heated liquid elastomer  71  is applied to the top surface  51   e   1  of the elastomer support rib  51   e  (liquid elastomer application step). Then, the applied liquid elastomer  71  is solidified by cooling. Referring to  FIG. 35 , as the liquid elastomer  71  is applied to the top surface  51   e   1  of the elastomer support rib  51   e , it flows into the groove  51   e   11 , increasing thereby the contact area between the elastomer support rib  51   e  and the elastomer  71  (enlarged cross-sectional views at lines H-H and G-G in  FIGS. 33 and 40 , respectively). That is, providing the flange  51   d  with the groove  51   e   11  increases the strength of the bond between the elastomer  71  and liquid elastomer application surface  51   e   1 . Hereafter, the top surface  51   c   1  of the elastomer support rib  51   e  will be referred to as elastomer application surface  51   e   1 . Further, the solidified elastomer  71  will be referred to simply as elastomer  71 . 
     FIG. 36  is a schematic drawing of the portion of the elastomer  71 , which corresponds in position to the connective portion  51   e   1  of the elastomer support rib  51   e.    
   On the connective portion  51   e   12 , the lengthwise end of the elastomer  71 , which corresponds in position to the point at which the application of liquid elastomer  71  is started, and the other lengthwise end of the elastomer  71 , which corresponds in position to the point at which the application of the liquid elastomer  71  is ended, are connected to each other in such a manner that the two lengthwise ends overlap in terms of the width direction of the connective portion  51   e   12 . The elastomer  71  is roughly semicircular in cross section (cross section at plane indicated by arrow marks J and J). The lengthwise end of the elastomer  71 , which corresponds in position to the point at which the application of liquid elastomer  71  is started, and the other lengthwise end of the elastomer  71 , which corresponds in position to the point at which the application of the liquid elastomer  71  is ended, are arcuate in contour (cross section at plane indicated by arrow marks K and K). 
     FIG. 37  is a perspective view of he developer storage frame  61  as seen from the developing means frame  51  side.  FIG. 38  is a perspective view of the developer storage frame  61  prior to the attachment of the elastic sealing members  81 ,  82 ,  83 , and  84  to the developer storage frame  61 .  FIG. 39  is a perspective view of the developer storage frame  61  after the attachment of the elastic sealing members  81 ,  82 ,  83 , and  84  to the developer storage frame  61 . 
   Next, the developer storage frame  61  shown in  FIG. 37  is prepared (development storage frame preparation step). The developer storage frame  61  has a flange  61   b  as the first connection portion. The four corners of the flange  61   b  have four grooves  61   g   1 ,  61   g   2 ,  61   g   3 , and  61   g   4 , which correspond in position to the outward areas of the four corners (corner areas)  61   b   5 ,  61   b   6 ,  61   b   7 , and  61   b   8  of the opening  61   a . The grooves  61   g   1 ,  61   g   2 ,  61   g   3 , and  61   g   4  are positioned so that their positions coincide with the portions of the elastomer  71 , which are on the outward areas of the four corners of the opening  51   a  of the developing means frame  51 . Further, the grooves  61   g   1 ,  61   g   2 ,  61   g   3 , and  61   g   4  are surrounded by ribs  61   h   1 ,  61   h   2 ,  61   h   3 , and  61   h   4 , which protrude toward the developing means frame  51 . 
   The developer storage frame  61  has ribs  61   f   1 ,  61   f   2 ,  61   f   3 , and  61   f   4 , which are positioned so that they are on the outward side of the straight edge portions of the opening  61   a , that is, the portions other than the portions corresponding to the four corner of the opening  61   a . Further, the ribs  61   f   1 ,  61   f   2 ,  61   f   3 , and  61   f   4  are on the outward side of the portions of the elastomer  71 , which are placed (coated) on the straight portions, that is, the portions other than the portions which correspond in position to the four corners of the opening  51   a  of the developing means frame  51 . The ribs  61   f   1 ,  61   f   2 ,  61   f   3 , and  61   f   4  protrude toward the developing means frame  51 , by a height greater than the height by which the ribs  61   h   1 ,  61   h   2 ,  61   h   3 , and  61   h   4  of the groove  61   g   1 ,  61   g   2 ,  61   g   3 , and  61   g   4 , respectively, protrude. 
   To the top surfaces of the ribs  61   f   1 ,  61   f   2 ,  61   f   3 , and  61   f   4 , the elastic members  81 ,  82 ,  83 , and  84  are attached, respectively (elastic member attachment step) by their long edges portion. As for the examples of the means for attaching the elastic members  81 ,  82 ,  83 , and  84 , they may be attached using two-sided adhesive tape, or may be thermally welded ( FIGS. 38 and 39 ). The elastic members  81 ,  82 ,  83 , and  84  are in the form of a sheet, and are formed of metal or resin. 
   Into the grooves  61   g   1 ,  61   g   2 ,  61   g   3 , and  61   g   4 , the liquid elastomer  74  is injected using the dispenser  96  ( FIG. 12 ) ( FIGS. 38 and 39 ), so that the resultant body of the liquid elastomer  74  is slightly taller than the elastic members  81 ,  82 ,  83 , and  84 , and airtightly fill the gap between the adjacent two elastic members among the elastic members  81 ,  82 ,  83 , and  84 . Thereafter, the body of injected liquid elastomer  74  is solidified by cooling. 
   Further, the flange  61   b  of the developer storage frame  61  has a rib  61   i  as a pressure applying member, which protrudes toward the developing means frame  51  from the portion of the flange  61   b , which corresponds in position to the aforementioned connective portion  51   e   12  of the flange  51   d . Next, referring to  FIGS. 33 ,  37 , and  40 , the rib  61   i  will be described in detail. 
     FIG. 40  is a cross-sectional view of the joint between the developer storage frame  61  which does not have the rib  61   i  and elastic members  81 ,  82 ,  83 , and  84 , and the developing means frame  51  (and therefore, elastomer  71  is not deformed). 
   i) A height H 3  (enlarged cross-sectional view of area E in  FIG. 33 ) by which the rib  61   i  protrudes toward the developing means frame  51  side satisfies the following relationship:
 
 H 3 ≧H 1 −H 2.
 
   Referring to  FIG. 40 , the symbol H 1  stands for the distance from the developer storage frame  61  to the elastomer  71  after the joining of the developing means frame  51  and developer storage frame  61 , that is, the distance from the surface  61   n  of the flange  61   b  of the developer storage frame  61 , which is provided with the rib  61   i , to the tips  71   g  and  71   h  of the lengthwise ends  71   a  and  71   b  of the elastomer  71 . The symbol H 2  stands for the thickness of the elastic member  81  ( FIG. 33 ). 
   ii) The length L 1  ( FIG. 36 ) of the rib  61   i , that is, the dimension of the  61   i  in terms of the lengthwise direction of the developing means frame  51 , satisfies the following relationship:
 
 L 1= L 2+ L 3.
 
   A symbol L 2  stands for the distance from the liquid elastomer application start point  71   n  for the formation of the elastomer  71  to a preset point beyond the highest point  71   g  of the lengthwise end portion  71   a , that is, the end portion which corresponds to the liquid elastomer application start point  71   n . A symbol L 3  stands for the distance from the liquid elastomer application start point  71   n  to another preset point beyond the highest point  71   h  of the lengthwise end portion  71   b , which corresponds to the liquid elastomer application end point. 
   Thus, L 2  and L 4 , and L 3  and L 5 , satisfy the following relationship:
 
L2≧L4
 
L3≧L5.
 
   A symbol L 4  stands for the distance from the liquid elastomer application start point  71   n  to the point corresponding to the highest point  71   g  of the lengthwise end  71   a  corresponding to the liquid elastomer application start point  71   n . A symbol L 5  stands for the distance from the liquid elastomer application start point  71   n  to the point corresponding to the highest point  71   h  of the other lengthwise end of the elastomer  71 , which corresponds to the liquid elastomer application start point  71   n.    
   iii) The width W 1  ( FIG. 36 ) of the rib  61   i , that is, the dimension of the rib  61   i  in terms of the width direction of the rib  61   i , satisfies the following relationship:
 
 W 1= W 2+ W 3
 
   A symbol W 2  stands for the distance from the extension  71   p  of the plane of the contact area between the lengthwise end portions  71   a  and  71   b , which correspond to the liquid elastomer application starting and ending points, and a preset point beyond the center line  71   j  of the lengthwise end portion  71   a , in terms of the width direction of the elastomer  71 . A symbol W 3  stands for the distance from the abovementioned extension  71   p  to a preset point beyond the center line  71   k  of the lengthwise end portion  71   b , in terms of the width direction of the elastomer  71 . 
   Therefore, W 2  and W 4 , and W 3  and W 5 , satisfy the following relationship.
 
W2≧W4
 
W3≧W5
 
   A symbol W 4  stands for the distance from the extension  71   p  to the center line  71   j  of the lengthwise end portion  71   a , in terms of the width direction of the elastomer  71 . A symbol W 5  stands for the distance from the extension  71   p  to the center line  71   k  of the lengthwise end portion  71   b , in terms of the width direction of the elastomer  71 . 
   Referring to  FIG. 36 , the application of the liquid elastomer  71  leaves a gap (recess)  51   e   2  between the application start portion  71   a  of the elastomer  71 , and the application end portion  71   b  of the elastomer  71 , that is, where the application start and end portions  71   a  and  72 , respectively, are connected to each other). Referring to  FIG. 37 , the rib  61   i  is shaped and sized so that it can completely cover the recess  51   e   2 . 
     FIG. 44  is a perspective view of the developing means frame  51  and developer storage frame  61  joined (connected) by their flanges  51   d  and  61   b  in such a manner that they are movable relative to each other.  FIG. 33  is a cross-sectional view of the joint between the developing means frame  51  and developer storage frame  61 , showing the state of their connection.  FIG. 42  is a schematic drawing showing the state of the joint between the elastomer application start and end portions  71   a  and  71   b  of the elastomer  71  of the developing means frame  51  after the joining of the two frames  51  and  61 . 
   Referring to the enlarged cross-sectional view of the joint portion at the H-H line in the perspective view, in  FIG. 41 , as the developing means frame  51  and developer storage frame  61  are joined, the elastomer  71  coated on the developing means frame  51  makes contact with the elastic members  81 ,  82 ,  83 , and  84 , around the openings  51   a  and  61   a . More specifically, the elastomer  71  makes airtight contact with the third contact areas, that is, the free edge portions  81   a ,  82   a ,  83   a ,  84   a  (end portions opposite to anchored portions in terms of width direction) of the elastic members  81 ,  82 ,  83 , and  84 , respectively (elastic member contact step). 
   Further, the third free edge portion  81   a  (connective portion) of the elastic member  81  is airtightly pressed upon the elastomer  71  of the developing means frame  51  by the rib  61   i  of the developer storage frame  61  (enlarged cross-sectional view of portion E in  FIG. 33 , at line E-E in  FIG. 41 ). That is, upon the start and end portions  71   a  and  71   b  of the elastomer  71 , the third connective portion  81   a  (free edge portion) is airtightly pressed by the rib  61   i . It should be noted here that before the rib  61   i  and third connective portion  81   a  come into contact with each other, a gap  51   e   3  is present, or is likely to be created, between the portions  71   c  and  71   d  of the recess  51   e   2 , and the third connective area  81   a . However, as the rib  61   i  and third connective area  81   a  come into contact with each other, the third connective area  81   a  is pressed toward the recess  51   e   2 . Thus, the third connective area  81   a  is pressed upon the portions  71   c  and  71   d  in a manner fill the gap  51   e   3  ( FIG. 42 ). Further, the elastomers  71  and  74  with which the developing means frame  51  and developer storage frame  61  are provided, respectively, are pressed upon each other (cross-sectional view at line G-G). Therefore, the joint between the flanges  51   d  and  61   b  is sealed by the elastomers  71  and  74 . Therefore, the toner stored in the developer storage frame  61  is prevented from leaking through the joint between the flanges  51   d  and  61   b.    
   The elastomer  71  is high in conformance. Therefore, the amount of compressive force which must be applied to make the elastomer  71  to effectively perform as a sealing member is relatively small. That is, when the elastomer  71  is used to seal between the flanges  51   d  and  61   b , the amount by which the elastomer  71  need to be compressed is relatively small. Therefore, when the elastomer  71  is used as the sealing member to seal between the flanges  51   d  and  61   b , the amount of the reactive force generated by the sealing member (elastomer  71 ) is relatively small. In other words, the usage of the elastomer  71  as the sealing member between the flanges  51   d  and  61   b  makes it possible to reduce the amount of the pressure (which hereafter will be referred to as pressure D) which applies to the peripheral surface of the photosensitive drum  10  through the rings  26   a  and  26   b  fitted around the lengthwise ends of the development roller  20 , one for one. To sum up, the pressure D can be kept low by sealing between the flanges  51   d  and  61   b  by placing the elastomer  71  between the flanges  51   d  and  61   b.    
   The reduction in the pressure D reduces the amount by which the photosensitive drum  10  is frictionally worn, amount by which the shaft  15  which rotatably supports the photosensitive drum  10  is frictionally worn, and amount by which the development roller  20  is frictionally worn, and amount by which the bearing  16  which rotatably supports the development roller  20  is frictionally worn. It also reduces the amount by which the rings  26   a  and  26   b , which are kept pressed upon the peripheral surface of the photosensitive drum  10 , are frictional worn, and the amount by which the portions of the peripheral surface of the photosensitive drum  10 , which correspond in position to the rings  26   a  and  26   b , are frictionally worn. Thus, the reduction in the pressure D can extends lives of the abovementioned components  10 ,  15 ,  16 ,  20 ,  26   a ,  26   b ,  27   a , and  27   b.    
   Moreover, the reduction in the pressure D reduces the amount by which heat is frictionally generated in the contact area between the photosensitive drum  10  and shaft  15 , and the amount by which heat is frictionally generated in the contact area between the photosensitive drum  10  and bearing  16 , as the photosensitive drum  10  is rotated. The reduction in the amount of the pressure D also reduces the amount by which heat is frictionally generated in the contact area between the development roller  20  and bearing  27   a , and the contact area between the development roller  20  and bearing  27   b , as the development roller  20  is rotated. Further, it reduces the amount by which heat is frictionally generated in the contact area between the peripheral surface of the photosensitive drum  10  and ring  26   a , and contact area between the peripheral surface of the photosensitive drum  10  and ring  26   b , as the photosensitive drum  10  and development roller  20  are rotated. Thus, the reduction in the pressure D makes it possible to reduce the number of fans necessary to be placed in the apparatus main assembly D, making it therefore possible to reduce the amount of electric power consumed by the fans. 
   Further, the reduction in the pressure D reduces the amount by which the development roller  20  deforms by being kept pressed toward the photosensitive drum  10 . Thus, the reduction in the pressure D makes it less likely for an image, which is nonuniform in density, to be formed due to the deformation of the development roller  20  attributable to the abovementioned contact pressure between the development roller  20  and photosensitive drum  10 ; the reduction in the pressure D can improve the image forming apparatus in image quality. 
   Incidentally, the developing means frame  51  and/or developer storage frame  61  are not perfectly uniform in measurements. Therefore, the amount by which the sealing member for sealing the joint between the developing means frame  51  and developer storage frame  61  must be compressed to airtightly seal the joint varies. However, using the elastomers  71  and  74  as the sealing members minimizes the effects of the nonuniformity in the measurements of the developing means frame  51  and/or developer storage frame  61 ; it can keep the pressure D low. Moreover, providing the developer storage frame  61  with the elastic members  81 ,  82 ,  83 , and  84 , in addition to using the elastomers  71  and  74 , further reduces the effects of the nonuniformity in the measurements of the developing means frame  51  and/or developer storage frame  61  upon the amount of reactive force which the elastomers  71  and  74  generate. Therefore, it can keep the pressure D low in spite of the nonuniformity in the measurements of the developing means frame  51  and developer storage frame  61 . 
   Also in this embodiment, not only is the elastomer  71  placed (coated) on the elastomer support rib  51   e , but also, the elastomer  74  is placed on the corner areas of the flange  61   d . In addition, the elastic members  81 ,  82 ,  83 , and  84  are attached to the straight edges portions of the flange  61 . Instead, however, the elastomer  71  may be attached to the developer storage frame  61  by providing the developer storage frame  61  with an elastomer support rib, whereas the elastic members  81 ,  82 ,  83 , and  84  may be attached to the straight edge portions of the flange  51 . 
   Further, the elastic members  81 ,  82 ,  83 , and  84  may be the third connective portions integrally formed with the developer storage frame  61  or developing means frame  51 . 
   In this embodiment, the third connective area  81   a  of the elastic member  81  is airtightly pressed on the elastomer  71  of the developing means frame  51  by the rib  61   i  of the developer storage frame  61 . However, the rib  61   i  may be replaced with a pressing member formed of foamed substance or elastomer.  FIG. 43  is a cross-sectional view of the joint between the flange  61   b  of the developer storage frame  61  having a member formed of a foamed substance, instead of the rib  61   i , and the flange  51   d  having the elastomer  71 .  FIG. 44  is a cross-sectional view of the joint between the flange  61   b  of the developer storage frame  61  having the elastomer  72 , instead of the rib  61   i , and the flange  51   d  having the elastomer  71 . The usage of an elastic pressing member  91  formed of a foamed substance, in place of the rigid rib  61   i , in combination with the elastomer  72 , can reduce the effects of the nonuniformity in the measurements of the developing means frame  51  and/or developer storage frame  61 , upon the amount by which the elastomers  71  and  72  generate reactive force. Therefore, it can keep the pressure D low. The elastic pressing member  91  formed of a foamed substance, and elastomer  71 , may be attached to the flange  61   b  side of the third connective area  81   a , instead of the flange  61   b  of the developer storage frame  61 . Such an arrangement is just as effective as the arrangement in this embodiment. 
   (2) Modified Method for Assembling the Developing Means Frame  51  and Developer Storage Frame  61   
   In this embodiment, the elastomer  71  is formed on either frame  51  or  61  by applying liquid elastomer  71  thereto. However, the elastomer  71  may be formed on the elastic member  81  by applying liquid elastomer  71  to the elastic member  81  (liquid elastomer application step). Incidentally, applying liquid elastomer  71  to the frames  51  and/or  61  is better in terms of assembly operation efficiency than applying liquid elastomer  71  to the elastic member  81 . There are essentially two different methods for applying liquid elastomer  71  to the elastic member  81 : a method (pre-attachment liquid elastomer application method) in which the elastomer  71  is applied to the elastic member  81  before the elastic member  81  is attached to the frame  51  or  61 , and a method (post-attachment liquid elastomer application method) in which the elastomer  71  is applied to the elastic member  81  after the elastic member is attached to frame  51  or  61 . Of the two different steps, the former is superior in assembly operation efficiency to the latter. Incidentally, after the completion the former, or the method in which the liquid elastomer  71  is applied before the attachment of the elastic member  81 , the elastomer  71  attached to the elastic member  81  is placed in contact with the frame  51  or  61  (frame joining step), or the elastic member  81  to which the elastomer  71  has been attached is attached to the frame  51  or  61 . Further, after the liquid elastomer is applied to the elastic member  81  attached to the frame  51  or  61 , the elastomer  71  is placed in contact with the frame  51  or  61 . 
   Further, the elastomer  71  attached (coated) to the frame  51  or  61  is placed in contact with the elastic member  81  (elastic member contact step), and then, the elastic member  81  may be attached to the frame  51  or  61  (elastic member attachment step). 
   Incidentally, the unmodified method in this embodiment is superior in assembly operation efficiency to these modified versions of the assembly method in this embodiment. 
   (3) Miscellaneous 
   Further, in this embodiment, the liquid elastomers  71 ,  72 , and  74  are solidified by cooling. However, the method for solidifying the liquid elastomers  71 ,  72 , and  74  does not need to be limited to cooling. For example, they may be solidified by chemical reaction, that is, by mixing the liquid elastomers with another liquid. 
   Also in this embodiment, when assembling the development unit A, the developing means frame  51  and developer storage frame  61  can be joined simply by moving the developer storage frame  61  relatively the developing means frame  51  in a single direction. Therefore, this embodiment can improve the efficiency with which the development unit A is assembled. 
   Embodiment 6 
   Next, another example of the development unit A will be described. 
   The components in this embodiment, which are identical to the counterparts in the fifth embodiments, are given the same reference numerals and characters as those given to the counterparts, and will not be described. The development unit A in this embodiment also is integrally joined with the photosensitive member unit B to form a cartridge C, as is the development unit A in the first embodiment. 
     FIG. 45  is a drawing of the developer storage frame  6  of the development unit A in the sixth embodiment.  FIG. 46  is a schematic drawing showing the relationship among the rib  61   i  of the developer storage frame  61 , elastic member  85 , and elastomer  71  of the developing means frame  51 . 
   The developer storage frame  61  is provided with a rib  61   m  in the form of a rectangular frame, which extends along the edges of the flange  61   b , and the elastic member  85  in the form of a rectangular frame, which is adhered to the rib  61   m  with the use of two-sided adhesive tape. Otherwise, the structure of the developer storage frame  61  in this embodiment is the same as that of the developer storage frame  61  in the first embodiment. This elastic member  84  is formed of sheet of an elastic (stretchable, shrinkable, and flexible) substance (for example, foamed substance, rubber, and the like). That is, in this embodiment, the flange  61   b  is provided with the rib  61   m  in the form of a rectangular frame, and the elastic member  85  is adhered to the rib  61   m  with the use of two-sided adhesive tape, instead of the ribs  61   h   1 ,  61   h   2 ,  61   h   3 , and  61   h   4  and the elastomer  71 , with which the flange  61   b  in the first embodiment is provided. 
   Therefore, the development unit A in this embodiment is the same in function and effect as the development unit A in the fifth embodiment. 
   According to the preceding embodiments, it is possible provide a developing apparatus capable of keeping satisfactorily sealed the joint between the first frame which stores developer, and the second frame which supports the developer bearing member, while controlling the amount of force applied from the first frame to the second frame, a process cartridge comprising such a developing apparatus, and an electrophotographic image forming apparatus in which such a process cartridge is removably mountable. Further, it is possible to simplify the process for assembling the developing apparatus. 
   While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims. 
   This application claims priority from Japanese Patent Applications Nos. 115611/2006 and 115612/2006 both filed Apr. 19, 2006 which are hereby incorporated by reference.