Abstract:
A cartridge detachably mountable to a main assembly of the image forming apparatus includes an image bearing member; a frame having an opening for exposing the image bearing member; a movable shutter member movable between a closing position for closing the opening and an open position for opening the opening; and a holding portion for abutting to the shutter member to hold the shutter member at the closing position, wherein the shutter member is elastically deformable to ride over the holding portion to permit the shutter member to move from the closing position to the open position.

Description:
FIELD OF THE INVENTION AND RELATED ART 
       [0001]    The present invention relates to a cartridge which is removably mountable in the main assembly of an image forming apparatus and does not require a pressure applying means to keep its shutter closed. It also relates to an image forming apparatus which employs such a cartridge. 
         [0002]    In this specification, an “image forming apparatus” means an apparatus which forms an image on recording medium with the use of an electrophotographic image formation process. Examples of an image forming apparatus include an electrophotographic copy machine, an electrophotographic printer (laser beam printer and LED (light emitting diode) printer, for example), a facsimile apparatus, a word processor, and the like. 
         [0003]    A “process cartridge” means a cartridge in which an electrophotographic photosensitive drum, and one or more means for processing the electrophotographic photosensitive drum, are integrally placed, and which is mountable in the main assembly of an image forming apparatus. Examples of processing means include a charging means, a developing means, a cleaning means, and the like. 
         [0004]    In the field of an image forming apparatus which uses an electrophotographic image formation process, it has been a common practice to employ a process cartridge system, which integrally places an electrophotographic photosensitive member, and means for processing the electrophotographic photosensitive member, in a cartridge which is removably mountable in the main assembly of an electrophotographic image forming apparatus. A process cartridge system makes it possible for a user to maintain an electrophotographic image forming apparatus by him- or herself, that is, without relying on a service person. Thus, this system has come to be widely used in the field of an electrophotographic image forming apparatus. 
         [0005]    Japanese Laid-open Patent Application H09-26740 discloses a process cartridge which is removably mountable in the main assembly of an image forming apparatus. This process cartridge has a rotatably movable shutter for protecting the photosensitive drum in the process cartridge. The shutter is attached to the frame of the process cartridge. It is enabled to move between its closed position and open position. The closed position is for protecting the photosensitive drum, whereas the open position is for keeping the photosensitive drum exposed from the frame of the process cartridge. Further, the shutter is kept under the pressure from a pressure applying means, such as a spring, with which the process cartridge is provided. Thus, until the process cartridge is mounted into the main assembly of an image forming apparatus, the shutter remains in its closed position. As the process cartridge is inserted into the main assembly of an image forming apparatus, the shutter comes into contact with the main assembly. Thus, as the process cartridge is inserted further into the main assembly, the shutter is moved from its closed position to its open position by the main assembly, against the pressure from the pressure applying means. On the other hand, as the process cartridge in the main assembly is moved outward of the main assembly to be moved out of the main assembly, the shutter is moved from its open position to its closed position by the pressure from the pressure applying means. 
       SUMMARY OF THE INVENTION 
       [0006]    A process cartridge in accordance with the prior art described above requires a pressure applying means for keeping its shutter in the closed position while the process cartridge is out of the main assembly of an image forming apparatus. Moreover, when the process cartridge is assembled, the pressure applying means has to be attached to the shutter, and the frame of the process cartridge. 
         [0007]    Thus, the primary object of the present invention is to provide a process cartridge, which is significantly smaller in the number of components related to its shutter, superior in terms of the efficiency with which it can be assembled, and yet, is as good as, or superior to, a process cartridge in accordance with the prior art, in terms of shutter function. 
         [0008]    According to an aspect of the present invention, there is provided a cartridge detachably mountable to a main assembly of the image forming apparatus, comprising an image bearing member; a frame having an opening for exposing said image bearing member; a movable shutter member movable between a closing position for closing said opening and an open position for opening said opening; and a holding portion for abutting to said shutter member to hold said shutter member at the closing position, wherein said shutter member is elastically deformable to ride over said holding portion to permit said shutter member to move from the closing position to the open position. 
         [0009]    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 
         [0010]      FIG. 1A  is a schematic sectional view of the electrophotographic image forming apparatus when a process cartridge in the first preferred embodiment of the present invention is in the apparatus, and shows the general structure of the apparatus.  FIG. 1B  is a perspective view of the process cartridge in the first preferred embodiment of the present invention, which has a shutter holding means for keeping the shutter closed, and shows the general structure of the cartridge. 
           [0011]      FIG. 2  is a sectional view (a) of the process cartridge in the first embodiment of the present invention, when the shutter of the cartridge is in its position for keeping covered the drum exposure opening of the cartridge, and is a sectional view (b) of the process cartridge in the first embodiment of the present invention when the shutter of the process cartridge is in its position for keeping properly exposed the drum exposure opening of the cartridge. 
           [0012]      FIG. 3  is a schematic sectional view (a) of the electrophotographic image forming apparatus in the first preferred embodiment of the present invention, and shows the general structure of the cartridge guiding rails and cartridge holding member of the main assembly of the image forming apparatus, and is a perspective view (b) of the process cartridge in the first preferred embodiment of the present invention, and shows the portions of the process cartridge, by which the process cartridge is guided when it is mounted into, or dismounted from, the main assembly of an image forming apparatus. 
           [0013]      FIG. 4  is a schematic sectional view of the shutter, and its adjacencies, of the process cartridge in the first preferred embodiment, and depicts the mechanism for closing the shutter as the process cartridge is moved out of the main assembly of the electrophotographic image forming apparatus. 
           [0014]      FIG. 5  is a perspective view (a) of the process cartridge in the second preferred embodiment of the present invention, which has two shutter holding means. It depicts the process cartridge when the shutter is in its closed position, and is a sectional view (b) of the process cartridge in the second preferred embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 1 
       [0015]    First, referring to  FIGS. 1A ,  1 B and  2 - 4 , the first preferred embodiment of the present invention is described. 
       [General Structure of Electrophotographic Image Forming Apparatus] 
       [0016]      FIG. 1A  is a schematic sectional view of the electrophotographic image forming apparatus (laser beam printer) in the first preferred embodiment of the present invention, when a process cartridge B, which is in accordance with the present invention, is in its proper position for image formation in the main assembly of the image forming apparatus. It shows the general structure of the image forming apparatus. First, the image forming apparatus in this embodiment is described with reference to  FIG. 1A . The image forming operation of the image forming apparatus in this embodiment is as follows: First, a latent image is formed on the peripheral surface of a photosensitive drum  7  (image bearing member) by exposing the peripheral surface of the photosensitive drum  7  to the beam of laser light projected, while being modulated according to the information regarding the image to be formed, from an optical system  1 . This latent image is developed into a visible image (toner image), that is, an image formed of toner, with the use of developer (which hereafter may be referred to as toner). In synchronism with the formation of the toner image, a sheet  2  of recording medium is moved out of a sheet feeder cassette  3 , and is conveyed though the main assembly of the image forming apparatus. While the sheet  2  of recording medium is conveyed though the main assembly, the toner image on the photosensitive drum  7  is transferred onto the sheet  2  of recording medium by a transfer roller  4 . Then, the toner image is fixed to the sheet  2  of recording medium by a fixing means  5 . Then, the sheet  2  of recording medium is discharged into a delivery tray  6 . 
       [Process Cartridge] 
       [0017]    Next, referring to  FIG. 1B  and  FIG. 2 , the process cartridge B (which hereafter will be referred to simply as cartridge B) is described. First, referring to  FIG. 2 , the cartridge B comprises a photosensitive drum unit and a development unit C. The photosensitive drum unit is made up of photosensitive drum  7 , a cleaning blade  13 , and a drum supporting frame  10  which supports the photosensitive drum  7 , cleaning blade  13 , etc. The development unit C is made up of a toner chamber  8 , developing means such as a development roller  12 , and a developing means frame  9  which supports the developing means. The drum supporting frame  10  and developing means supporting frame  9  are in connection with each other in such a manner that they are rotationally movable relative to each other. The cartridge B is structured so that it is removably mountable in the main assembly of an image forming apparatus A (which may be referred to simply as apparatus main assembly, hereafter). The toner chamber  8  has an opening  16 . When the cartridge B is brand-new, the opening  16  remains sealed with a seal  17 . Thus, when the cartridge B which is brand-new is used for the first time, the seal  17  has to be pulled out to unseal the opening  16 . As the material for the seal  17 , a sheet or plate of PET (polyethylene-terephthalate, PPS (polyphenylene-sulfide), or the like can be used. 
         [0018]    The toner (unshown) in the frame  8  (toner chamber) is sent to the frame  9  (developing means supporting frame) through the opening  16 . Then, it is coated on the peripheral surface of the development roller  12  while being formed into a layer of frictionally charged toner, by a development blade  11 . Then, the toner particles in the toner layer is transferred onto the peripheral surface of the peripheral surface of the photosensitive drum  7  in the pattern of the electrostatic latent image on the peripheral surface of the photosensitive drum  7 . As a result, a visible image is formed of the toner on the peripheral surface of the photosensitive drum  7 . Then, the visible image (image formed of toner) is transferred onto the sheet  2  of recording medium by a transfer roller  4 , which is shown in  FIG. 1A . Then, the toner particles remaining on the peripheral surface of the photosensitive drum  7  are scraped into the waste toner storage chamber  14  by the cleaning blade  13 . Then, the portion of the peripheral surface of the photosensitive drum  7 , from which the residual toner particles have just been scraped away by the cleaning blade  13 , is uniformly charged by a charge roller  15  to be prepared for the formation of a latent image by the optical system  1 . The charge roller  15 , development roller  12 , cleaning blade  13 , etc., are the processing means for processing the photosensitive drum  7 . The cartridge frame  34  has the frame  8  (toner chamber), frame  9  (developing means supporting frame), and frame  10  (drum supporting frame). It is in the cartridge frame  34  that the photosensitive drum  7  (image bearing member), and the processing means for processing the photosensitive drum  7 , are held. 
       [Structure of Shutter] 
       [0019]    Next, referring to  FIG. 2  which is a sectional view of the cartridge B, the structure of the shutter  18  is described. The cartridge B has an opening  27 , which is between the frame  10  and  9  of the cartridge frame  34 . It is through the opening  27  that the photosensitive drum  7  (image bearing member) becomes exposed as the shutter  18  is opened. More specifically, referring to  FIG. 1A , the position of the opening  27  relative to the cartridge B is such that when the cartridge B is its image formation position in the main assembly of the image forming apparatus A, it faces downward and allows the photosensitive drum  7  to contact the sheet  2  of recording medium. Further, the cartridge B is provided with the shutter  18  which is elastic. As the cartridge B is mounted into, or removed from, the main assembly of the image forming apparatus A, the shutter  18  is made to expose, or cover, the opening  27  by the movement of the cartridge B. 
         [0020]    As the material for the elastic shutter  18 , HIPS (high impact polyethylene) can be used, for example. HIPS is a combination of PS (polystyrene) and rubbery polymer or copolymer. Substances selectable as the preferable rubbery copolymer for the shutter  18  are poly-butadiene, styrene-butadiene copolymer, polyisoprene, butadiene-isoprene copolymer, natural rubber, ethylene-propylene copolymer, and the like. By using substances, such as those listed above, which contain rubbery substance(s), as the material for the shutter  18 , it is possible to provide the shutter  18  with a greater amount of elasticity than by using substances which have not been increased in elasticity with the addition of rubbery substances. Incidentally, the materials for the shutter  18  do not need to be limited to HIPS. That is, the elastic shutter  18  may be formed of ABS (acrylonitrile-butadiene-styrene copolymer), denatured PPE (denatured polyphenylene-ether resin), for example. 
         [0021]    Referring to (a) of  FIG. 2 , when the cartridge B is brand-new, the shutter  18  keeps the opening  27  completely covered to protect the photosensitive drum  7  (shutter position  18   a  in (a) of  FIG. 2 ). Next, referring to (b) of  FIG. 2 , the cartridge B is structured so that as the cartridge B is inserted into the main assembly of the image forming apparatus A to be used, the shutter  18  is rotationally moved about a shaft  28 , shown in  FIG. 1B , to expose the opening  27  so that the photosensitive drum  7  is allowed to contact the sheet  2  of recording medium (shutter position  18   b  in FIG.  2 (( b ))). 
         [0022]    Referring to  FIG. 1B , the cartridge B is structured so that the shutter  18  is rotationally movable about the pair of shafts  28 , which project outward from the side walls of the cartridge frame  34  in the lengthwise direction of the cartridge B, one for one, being thereby enabled to move between the closed position  18   a  and open position  18   b.    
       [Structure of Shutter Holding Means] 
       [0023]    Next, referring to  FIGS. 1B and 2 , the shutter holding means (shutter holding member) of the cartridge B is described.  FIG. 1B  is a schematic sectional view of the cartridge B, and FIG.  2 (( a )) is a schematic sectional view of the cartridge B when the shutter  18  is over the opening  27 .  FIG. 2(   b ) is a schematic sectional view of the cartridge B when the shutter  18  is away from the opening  27 . 
         [0024]    In this embodiment, the shutter holding means is a projection  19 , which is on the outward surface of the frame  10  (drum supporting frame) of the cartridge frame  34 . In terms of the lengthwise direction of the cartridge B, the projection  19  is roughly in the middle of the cartridge B. It is perpendicular to the outward surface of the frame  10 . The projection  19  holds the shutter  18  in the closed position  18   a  ( FIG. 1B  and (a) of  FIG. 2 ) when the cartridge B is out of the image forming apparatus A. Further, it holds the shutter  18  in the open position  18   b  ( FIG. 1B  and (b) of  FIG. 2 ) when the cartridge B is in its image forming position in the main assembly of the image forming apparatus A. The projection  19  may be a simple projection, or in the form of a rib. 
         [0025]    Next, referring to  FIG. 2 , as the cartridge B is inserted into the main assembly of the image forming apparatus A, the shutter  18  is moved upstream in terms of the cartridge insertion direction, over the projection  19  while being elastically deformed, and then, to its open position, exposing thereby the opening  27 . On the other hand, as the cartridge B in the main assembly of the image forming apparatus A is moved outward of the main assembly, the shutter  18  is moved upstream in terms of the cartridge extraction direction, over the projection  19 , while being elastically deformed, and then, to its closed position  18   a , covering thereby the opening  27 . The shutter  18  is roughly rectangular, and its lengthwise direction is parallel to the lengthwise direction of the cartridge B. Its size is large enough to fully cover the opening  27 . Thus, the shutter  18  is enabled to relatively easily bend in the direction perpendicular to its lengthwise direction, being therefore capable of easily moving over the projection  19 . Moreover, the projection  19  is shaped so that in terms of its cross section at a plane which is parallel to the moving direction of the shutter  18  and perpendicular to the lengthwise direction of the cartridge B, it is in the form of a parallelepiped, having slanted surfaces  20   a  and  20   b  which are perpendicular to the rotational movement of the shutter  18  about the shaft  28 . This structural arrangement reduces the mount of the resistance which the shutter  18  encounters as it moves over the projection  19 , and therefore, makes it possible for the shutter  18  to smoothly move. 
         [0026]    Referring to (a) of  FIG. 2 , when the cartridge B is outside the main assembly of the image forming apparatus A, an edge  18   c  of the shutter  18  is in contact with the slanted surface  20   a  of the projection  19 . Thus, the shutter  18  is held in its closed position  18   a  by the projection  19 . 
       [Structural Arrangement for Allowing Process Cartridge to be Removably Mounted] 
       [0027]    Next, referring to  FIG. 3 , the structural arrangement which allows the cartridge B to be removably mounted in the main assembly of the image forming apparatus A is described.  FIG. 3(   a ) is a schematic sectional view of the image forming apparatus, and depicts the general structure of the apparatus, in particular, the guide rails  21   a - 21   c  with which the main assembly of the image forming apparatus A is provided to guide the cartridge B when the cartridge B is inserted into the apparatus main assembly, and the shutter catching member with which the main assembly of the image forming apparatus A is provided to close the shutter  18 . FIG.  3 (( b )) is a perspective view of the cartridge B, and depicts the structure of the cartridge guide (guiding member) of the cartridge B, which guides the cartridge B when the cartridge B is mounted into, or removed from, the main assembly of the image forming apparatus A. 
         [0028]    Referring to  FIG. 3(   a ), the cartridge B has a pair of guides, which are on the lengthwise end surfaces of the cartridge frame  34 , one for one. The guides correspond in position to the guide rails  21   a - 21   c  of the main assembly of the image forming apparatus A. Next, referring to FIG.  3 (( b )), the shutter  18  is provided with a pair of guide bosses  22 , which are on the lengthwise end surfaces of the shutter  18 , one for one, and are perpendicular to the end surfaces. Further, the cartridge B is provided with a pair of guide ribs and a pair of cartridge positioning bosses  29 , which also are on the lengthwise end surfaces of the cartridge frame  34 , one for one, and are perpendicular to the end surfaces. 
         [0029]    The method for mounting the cartridge B into the main assembly of the image forming apparatus A is as follows: First, the cartridge B is to be positioned relative to the main assembly of the image forming apparatus A so that the positioning bosses  29  and guide ribs  23  align with the first guide grooves  33  which the guide rails  21   a  and guide rails  21   b  form, and also, so that the guiding bosses  22  align with the second guide grooves  35  which the guide rails  21   b  and guide rail  21   c  form. Then, the cartridge B is inserted into the main assembly of the image forming apparatus A in such a manner that the positioning bosses  29  and guide ribs  23  follow the guide rails  21   a  and  21   b , whereas the guide bosses  22  follow the guide rails  21   b  and  21   c . Thus, as the cartridge B is moved into the main assembly of the image forming apparatus As described above, it dives into the space below the optical system  1  of the image forming apparatus A. 
         [0030]    The guide rail  21   b  is provided with a projection  21   b   1 , which is near the outward end of the guide rail  21   b , and which is triangular in cross section. Thus, as the cartridge B is inserted further into the main assembly of the image forming apparatus A, the guide boss  22  slides on the outward slanted surface  21   b   2  of the projection  21   b   1 , whereas the positioning boss  29  and guide rib  23  follow the first guide groove  33 . Then, as the cartridge B is inserted further into the main assembly of the image forming apparatus A, the shutter  18 , which was in its closed position, is rotationally moved about the shaft  28 , being thereby moved over the projection  19  while being elastically deformed, into its open position  18   b . Then, the positioning boss  29  fits into the recess  24  (receptacle for positioning boss  29 ) which is at the end of the first guide groove  33 , whereby the cartridge B is precisely position relative to the main assembly of the image forming apparatus A. As for the shutter,  18 , as the guide boss  22  fits into the recess  36 , which is at the inward end of the second guide groove  35 , whereby the shutter  18  is placed in its open position  18   b  as shown in FIG.  2 (( b )). Further, as the guide boss  22  fits into the recess  36 , the shutter  18 , which was remaining elastically deformed, regains its normal shape. Therefore, the other edge  18   d  of the shutter  18  is caught by the projection  19 , whereby the shutter  18  is retained in its open position  18   b  (FIG.  3 (( b ))). 
         [0031]    More specifically, the outward surface (slanted)  21   b   2  of the projection  21   b   1  of the guide rail  21   b , and the recess  36  (receptacle) of the guide rail  21   b , are the portions of the main assembly of the image forming apparatus A, which engage with the shutter  18  (guide boss  22 ) when the cartridge B is mounted into the main assembly of the image forming apparatus A. It is these portions that keep the shutter  18  elastically deformed while the shutter  18  is moved into its open position  18   b . Since the cartridge B and the main assembly of the image forming apparatus A are structured as described above, as the shutter  18  is rotationally moved to expose the opening  27 , it can be moved over the projection  19  while being elastically deformed. That is, the height of the projection  19  is such that it allows the shutter  18  to be moved from its closed position to its open position while causing the shutter  18  to elastically deform by the correct amount. 
         [0032]    Next, referring to  FIGS. 3 and 4 , the operation for extracting the cartridge B from the main assembly of the image forming apparatus A is described. First, the cartridge B is to be pulled outward in the direction parallel to the guide rails  21   a  and  21   b  so that the positioning boss  29  in the recess  24 , which is at the inward end of the first guide groove  33 , comes out of the recess  24  and moves onto the portion  24   a  of the first guide groove  33 , which is immediately adjacent to the recess  24 . As the cartridge B comes out of the recess  24  as described above, it is to be pulled diagonally upward so that the guide rib  23  and guide boss  22  follow the guide rails  21   a  and  21   b  as they did when the cartridge B was inserted. The upstream edge portion  18   c  of the shutter  18 , in terms of the direction in which the shutter  18  is rotationally moved to expose the opening  27 , has a pair of recesses  25  which function as a catch, whereas each of the guide rails  21   c  has a projection  26  which functions a hook, and the position of which corresponds to that of the recess  25 . 
         [0033]    Thus, the cartridge B is to be pulled diagonally upward so that the guide rib  23  and positioning boss  29  follow the guide rail  21   a  and  21   b , and also, so that the guide boss  22  follows the guide rail  21   b . Next, referring to FIG.  4 (( a )), each of the pair of guide rails  21  of the main assembly of the image forming apparatus A has a projection  26  (catching portion). Thus, as the cartridge B is pulled outward as described above, each projection  26  begins to engage into the corresponding recess  25  of the shutter  18 . Then, as the cartridge B is pulled further outward, the shutter  18  is caused to move over the projection  19  while being elastically deformed. The projection  26  remains engaged in the recess  25  until the shutter  18  reaches its closed position  18   a  (FIG.  4 (( b ))). Then, as the shutter  18  is moved into its closed position  18   a , the projection  26  comes out of the recess  25 . Therefore, the shutter  18  is allowed to restore its normal shape, causing its edge  18   c  to come into contact with the slanted surface  20   a  of the projection  19 , as shown in FIG.  2 (( a )). Thus, the shutter  18  is retained in its closed position  18   a  by the projection  19 . In other words, while the cartridge B is removed from the main assembly of the image forming apparatus A, the shutter  18  is closed by the outward movement of the cartridge B. 
         [0034]    Forming the projections  19  as an integral part of the cartridge frame  34  as described above can reduce the process cartridge B in component cost. Further, positioning the projection  19  roughly at the center of the cartridge B in terms of the lengthwise direction of the cartridge B makes it possible to prevent the shutter  18  from being twisted as it is opened or closed, and also, to improve the main assembly of the image forming apparatus A in the spatial efficiency; it can reduce the image forming apparatus in the internal space necessary for the mounting and dismounting of the cartridge B. 
       Embodiment 2 
       [0035]    Next, referring to  FIG. 5 , the second preferred embodiment of the present invention is described. In the first preferred embodiment, a single projection  19  was at roughly the center of the cartridge B in terms of the lengthwise direction of the cartridge B. In this embodiment, the cartridge B is provided with two projections  19 , which are near the lengthwise ends of the cartridge B, one for one. 
         [0036]    Referring to FIG.  5 (( a )), each projection  19  is on the outward surface of the frame  10  (drum supporting frame). Not only does it hold the shutter  18  in the closed position  18   a  of the shutter  18  when the cartridge B is out of the main assembly of the image forming apparatus A, but also, in the open position  18   b  of the shutter  18  when the cartridge B is its image forming position in the main assembly of the image forming apparatus. As the cartridge B is inserted into the main assembly of the image forming apparatus A, the shutter  18  exposes the opening  27  by being made to rotationally moved about the shaft  28 , moving over the projections  19  while being elastically deformed, whereas as the cartridge B is pulled outward when it is in the apparatus main assembly, the shutter  18  covers the opening  27  by being made to rotationally moved about the shaft  28 , moving over the projections  19  while being elastically deformed. 
         [0037]    The operation for mounting the cartridge B in this embodiment into, or removing it from, the main assembly of the image forming apparatus is the same as the operation for mounting the cartridge B in the first preferred embodiment into, or removing it from the main assembly of the image forming apparatus, and therefore, is not described. 
         [0038]    Since the cartridge B in this embodiment is provided with the pair of projections  19  which are in the adjacencies of the lengthwise ends of the cartridge B, one for one, it is unlikely for the shutter  18 , which is elastically flexible, to be twisted while the shutter  18  is opened or closed. Therefore, the shutter  18  is unlikely to interfere with a part or parts of the main assembly of the image forming apparatus A while the cartridge B is mounted into, or removed from, the main assembly. Also in this embodiment, when the shutter  18  is in its closed position  18   a , it is held by the lengthwise end portion of its long edge portion of  18   c  by the slanted surface  20   a  of each of the two projections  19 , whereas when it is in its open position  18   b , it is held at by the lengthwise end portions of its long edge  18   d  by the slanted surface  20   b  of each of the two projections  19 . Therefore, the shutter  18  in this embodiment is prevented from rattling. Therefore, it does not occur that the shutter  18  makes noises by resonating with the vibrations which result from the driving of the image forming apparatus A. Incidentally, the number of the projections  19  with which the cartridge B is provided may be three or more. Further, although the preceding preferred embodiments of the present invention were described with reference to a cartridge comprising a photosensitive drum, and processing means for processing the photosensitive drum, the present invention is also compatible with a drum cartridge, that is, a cartridge having only a photosensitive drum. 
       [Effects of Invention] 
       [0039]    The present invention makes it possible to hold the shutter of a cartridge without providing the cartridge (shutter) with a pressure applying means or the like dedicated to shutter retention. Thus, not only can the present invention reduce a cartridge in component count, but also, simplify the process of assembling a cartridge with a shutter. 
         [0040]    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. 
         [0041]    This application claims priority from Japanese Patent Applications Nos. 004591/2010 and 274388/2010 filed Jan. 13, 2010 and Dec. 9, 2010, respectively, which are hereby incorporated by reference.