Patent Publication Number: US-7711287-B2

Title: Cartridge and electrophotographic image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a cartridge detachably mountable to a main body of an electrophotographic image forming apparatus and an electrophotographic image forming apparatus to which the cartridge is detachably mountable. 
   2. Related Background Art 
   Conventionally, as an electrophotographic image forming apparatus that can form a color image, there is known an electrophotographic image forming apparatus in which developer images of respective colors are sequentially formed on one photosensitive drum using a plurality of developing devices for different colors. In addition, as disclosed in Japanese Patent Application Laid-Open No. 2002-244531, there is known an electrophotographic image forming apparatus in which a photosensitive drum and respective developing devices are adapted as cartridges detachably mountable to a main body of an image forming apparatus. In the following description, a cartridge having the electrophotographic photosensitive drum is referred to as a drum cartridge and a cartridge having the developing device is referred to as a developing cartridge. 
   In the electrophotographic image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-244531, a guide member is provided on an inner side of a right side plate and a left side plate of a main body frame of the apparatus main body. A mounting and detaching guide and a positioning portion for the cartridges are provided in the guide member. This allows the developing cartridge and the drum cartridge to be easily mounted and detached from the apparatus main body. Further, the cartridge can be accurately positioned with respect to the apparatus main body. 
   The main body frame and the guide member are required to accurately position the cartridges with respect to the apparatus main body and have rigidity for stably holding the cartridges. 
   In realizing a reduction in cost and a reduction in size of the apparatus main body, it is conceivable to reduce the thickness of the main body frame and the guide member provided on an inner side of the main body frame. However, in this case, the main body frame and the guide member tend to undergo a deflection. When the main body frame and the guide member undergo the deflection, it is likely that positioning accuracy deteriorates in positioning the cartridges with respect to the apparatus main body. 
   SUMMARY OF THE INVENTION 
   In view of the above-mentioned circumstances, it is an object of the present invention to provide a cartridge that can be accurately positioned with respect to an apparatus main body even if a reduction in cost of the apparatus main body is realized and an electrophotographic image forming apparatus including the cartridge. 
   It is another object of the present invention to provide a cartridge that can be accurately positioned with respect to an apparatus main body even if a reduction in size of the apparatus main body is realized and an electrophotographic image forming apparatus including the cartridge. 
   It is still another object of the present invention to provide a cartridge that can be accurately positioned with respect to an apparatus main body even if a thickness of a main body frame for supporting the cartridge, which is provided in the apparatus main body, is reduced and an electrophotographic image forming apparatus including the cartridge. 
   It is still another object of the present invention to provide a cartridge that can be accurately positioned with respect to an apparatus main body even if a reduction in cost and a reduction in size of the apparatus main body are realized by reducing a thickness of a main body frame for supporting the cartridge, which is provided in the apparatus main body, and an electrophotographic image forming apparatus including the cartridge. 
   It is still another object of the present invention to provide a cartridge that can be accurately positioned with respect to an apparatus main body by regulating a distance between sides of a main body frame by the cartridge even if the main body frame that undergoes a deflection is used and an electrophotographic image forming apparatus including the cartridge. 
   According to a representative structure of the present invention, in order to achieve the above-mentioned objects, an electrophotographic image forming apparatus that is detachably mounted with a cartridge and forms an image on a recording medium includes: one end side main body frame that supports one end side in a longitudinal direction of the cartridge mounted on the electrophotographic image forming apparatus, the one end side main body frame undergoing a deflection in the longitudinal direction; the other end side main body frame that supports the other end side in the longitudinal direction of the cartridge mounted on the electrophotographic image forming apparatus, the other end side main body frame undergoing a deflection in the longitudinal direction; and the cartridge that regulates a distance between the one end side main body frame and the other end side main body frame with the one end side in the longitudinal direction thereof supported by the one end side main body frame and the other end side in the longitudinal direction thereof supported by the other end side main body frame. 
   Also, according to another representative structure of the present invention, in order to achieve the above-mentioned objects, a cartridge is detachably mountable to a main body of an electrophotographic image forming apparatus that is detachably mounted with the cartridge and forms an image on a recording medium, the electrophotographic image forming apparatus having: one end side main body frame that supports one end side in a longitudinal direction of the cartridge mounted on the main body, the one end side main body frame undergoing a deflection in the longitudinal direction; and the other end side main body frame that supports the other end side in the longitudinal direction of the cartridge mounted on the main body, the other end side main body frame undergoing a deflection in the longitudinal direction, the cartridge including: a frame; one end side lock portion provided on one end side in a longitudinal direction of the frame; and the other end side lock portion provided on the other end side in the longitudinal direction of the frame, wherein the cartridge regulates a distance between the one end side main body frame and the other end side main body frame with the one end side in the longitudinal direction thereof supported by the one end side main body frame and the other end side in the longitudinal direction thereof supported by the other end side main body frame. 
   The present invention can provide a cartridge that can be accurately positioned with respect to an apparatus main body even if a reduction in cost of the apparatus main body is realized and an electrophotographic image forming apparatus including the cartridge. 
   The present invention can also provide a cartridge that can be accurately positioned with respect to an apparatus main body even if a reduction in size of the apparatus main body is realized and an electrophotographic image forming apparatus including the cartridge. 
   The present invention can further provide a cartridge that can be accurately positioned with respect to an apparatus main body even if a thickness of a main body frame for supporting the cartridge, which is provided in the apparatus main body, is reduced and an electrophotographic image forming apparatus including the cartridge. 
   The present invention can further provide a cartridge that can be accurately positioned with respect to an apparatus main body even if a reduction in cost and a reduction in size of the apparatus main body are realized by reducing a thickness of a main body frame for supporting the cartridge, which is provided in the apparatus main body, and an electrophotographic image forming apparatus including the cartridge. 
   The present invention can further provide a cartridge that can be accurately positioned with respect to an apparatus main body by regulating a distance between sides of a main body frame by the cartridge even if the main body frame that undergoes a deflection is used and an electrophotographic image forming apparatus including the cartridge. 
   Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional view of the schematic structure of a laser beam printer as an example of an electrophotographic image forming apparatus. 
       FIG. 2  is another sectional view of the schematic structure of the laser beam printer as an example of the electrophotographic image forming apparatus. 
       FIG. 3  is a front view of a state of a drum cartridge mounted on an apparatus main body according to a first embodiment of the present invention. 
       FIG. 4  is a sectional view of the state of the drum cartridge mounted on the apparatus main body according to the first embodiment. 
       FIG. 5  is a front view of a state of a drum cartridge mounted on an apparatus main body according to a second embodiment of the present invention. 
       FIG. 6  is a sectional view of the state of the drum cartridge mounted on the apparatus main body according to the second embodiment. 
       FIG. 7  is a perspective view of a state of a drum cartridge mounted on an apparatus main body according to a third embodiment of the present invention. 
       FIG. 8  is a sectional view of a state of mounting the drum cartridge on the apparatus main body according to the first embodiment. 
       FIG. 9  is a perspective view of the state of mounting the drum cartridge on the apparatus main body according to the first embodiment. 
       FIG. 10  is a partial enlarged view of the apparatus main body according to the first embodiment. 
       FIG. 11  is a sectional view of a state of mounting the drum cartridge on the apparatus main body according to the second embodiment. 
       FIG. 12  is a perspective view of the state of mounting the drum cartridge on the apparatus main body according to the second embodiment. 
       FIG. 13  is a partial enlarged view of the apparatus main body according to the third embodiment. 
   

   DESCRIPTION OF THE EMBODIMENTS 
   Exemplary embodiments of the present invention will be hereinafter described with reference to the accompanying drawings. Dimensions, materials, shapes, a relative arrangement thereof, and the like of components described in embodiments described below should be appropriately modified according to the structure and various conditions of an apparatus and a cartridge to which the present invention is applied. Therefore, unless specifically described otherwise, the scope of the present invention is not meant to be limited only to the dimensions, the materials, the shapes, the relative arrangement thereof, and the like. 
   First Embodiment 
   A first embodiment of the present invention is described. In the first embodiment, as an electrophotographic image forming apparatus, a color laser beam printer including one photosensitive drum and four developing devices is described as an example.  FIGS. 1 and 2  are sectional views of the schematic structures of the color laser beam printer. 
   First, an image forming operation of the color laser beam printer is described. In the embodiments described below, the electrophotographic image forming apparatus is detachably mounted with cartridges (developing cartridges  5  and a process cartridge  30 ) and forms an image on a recording medium S. As illustrated in  FIGS. 1 and 2 , the electrophotographic image forming apparatus (hereinafter referred to as image forming apparatus) has an electrophotographic photosensitive drum  2 . A plurality of (four) developing devices (developing cartridges)  5  ( 5   a ,  5   b ,  5   c ,  5   d ) are arranged around the photosensitive drum  2 . A charging roller  3  and a cleaning device  6  as process means that act on the photosensitive drum  2  are also arranged. Further, an exposure device  4  is also arranged. The charging roller  3  is charging means for uniformly charging the photosensitive drum  2 . The exposure device  4  is exposing means for irradiating the photosensitive drum  2  with a laser beam corresponding to image information and forming an electrostatic latent image on the photosensitive drum  2 . The developing devices  5  ( 5   a  to  5   d ) are developing means for developing the latent image, which is formed on the photosensitive drum  2 , with developers of colors (yellow, magenta, cyan, and black) corresponding to the developing devices  5  ( 5   a  to  5   d ) and visualizing the latent image. The developing device  5   a  contains the yellow developer and develops the latent image with the yellow developer. The developing device  5   b  contains the magenta developer and develops the latent image with the magenta developer. The developing device  5   c  contains the cyan developer and develops the latent image with the cyan developer. The developing device  5   d  contains the black developer and develops the latent image with the black developer. In other words, the developing devices  5  ( 5   a  to  5   d ) develop the electrostatic latent image, which is formed on the photosensitive drum  2 , with the developers. It should be noted that the developing devices  5  ( 5   a  to  5   d ) have developing rollers  25  and develop the latent image using the developing rollers  25 . The cleaning device  6  is cleaning means for removing a residual developer remaining on the photosensitive drum  2 . 
   The photosensitive drum  2  and the developing devices  5  ( 5   a  to  5   d ) are adapted as cartridges detachably mountable to a main body of an image forming apparatus A, respectively. In other words, the photosensitive drum  2  is provided in the process cartridge  30  detachably mountable to the apparatus main body A. In addition, the respective developing devices  5  ( 5   a  to  5   d ) are the developing cartridges  5  ( 5   a  to  5   d ) detachably mountable to the apparatus main body A. The respective cartridges are detachably mountable to the apparatus main body A independently from one another by an operator (user). In this embodiment, the cartridge  30  includes, besides the photosensitive drum  2 , the charging roller (charging means)  3 , the cleaning device (cleaning means)  6 , and a residual-developer containing portion  31  that contains a residual developer removed by the cleaning device  6 . In addition, the respective cartridges  5  ( 5   a  to  5   d ) are detachably mountable to a rotary (rotary supporting member)  1  provided in the apparatus main body A. 
   It should be noted that a process cartridge is a cartridge formed by integrating, for example, an electrophotographic photosensitive member and at least one of developing means, charging means, and cleaning means serving as the process means. Therefore, examples of the process cartridge include: a cartridge formed by integrating the electrophotographic photosensitive member and the developing means, the charging means, and the cleaning means serving as the process means; a cartridge formed by integrating the electrophotographic photosensitive member and the charging means serving as the process means; and a cartridge formed by integrating the electrophotographic photosensitive member and the charging means and the cleaning means serving as the process means. 
   The user can mount and detach the process cartridge and the developing cartridges from the apparatus main body. Therefore, the user can maintain the image forming apparatus without relying on a serviceperson. Consequently, maintainability of the image forming apparatus is improved. 
   The photosensitive drum  2  is rotated in an arrow direction (of  FIG. 2 , counterclockwise) in synchronization with the rotation of an intermediate transfer belt  7 . The surface of the photosensitive drum  2  is uniformly charged by the charging roller  3 . Simultaneously with the charging, light for the yellow image irradiates the photosensitive drum  2  by the exposure device  4 . Consequently, a yellow electrostatic latent image is formed on the photosensitive drum  2 . 
   Simultaneously with the latent image formation, the rotary (rotary supporting member)  1  that supports the four developing cartridges  5   a  to  5   d  is rotated. Then, the developing cartridge  5   a  containing the yellow developer is arranged in a developing position  18 X opposed to the photosensitive drum  2 . Then, a voltage having substantially the same polarity as a charging polarity of the photosensitive drum  2  and a potential substantially same as a potential of the photosensitive drum  2  is applied to the developing roller  25  to cause the yellow developer to adhere to the latent image formed on the photosensitive drum  2 . Consequently, the yellow developer is caused to adhere to the latent image to develop the latent image. In other words, the developing roller  25  develops the latent image. 
   Thereafter, a voltage having a polarity opposite to a polarity of the developer is applied to a primary transfer roller  8  arranged on an inner side of the transfer belt  7 . Consequently, the yellow developer image formed on the photosensitive drum  2  is primarily transferred onto the transfer belt  7 . 
   When the primary transfer of the yellow developer image is finished as described above, the developing cartridges  5   b  to  5   d  for the respective colors of magenta, cyan, and black are sequentially rotated and moved by the rotary  1 . Then, the developing cartridges  5   b  to  5   d  are positioned in a developing position  18 X opposed to the photosensitive drum  2 . Consequently, as in the case of yellow, the formation, the development, and the primary transfer of latent images are sequentially performed for the respective colors of magenta, cyan, and black. Then, four developer images are superimposed one on top of another on the transfer belt  7 . 
   While the developer images are formed and primarily transferred onto the transfer belt  7 , a secondary transfer roller  10  is not in contact with the transfer belt  7 . In addition, a cleaning unit  9  that removes a residual developer remaining on the transfer belt  7  is not in contact with the transfer belt  7  either. 
   On the other hand, sheets S as recording media are stored in a cassette  11  provided in a lower part of the image forming apparatus. The sheets S are separated and fed from the cassette  11  one by one by a sheet feeding roller  12  and fed to a registration roller pair  13 . The registration roller pair  13  forwards the fed sheet S to between the transfer belt  7  and the transfer roller  10 . At this time, the transfer roller  10  is in press contact with the transfer belt  7  (state illustrated in  FIG. 2 ). It should be noted that the recording media are media on which images are formed, for example, paper and an OHP sheet. 
   A voltage having a polarity opposite to the polarity of the developer is applied to the transfer roller  10 . And, the four-color developer images superimposed one on top of another on the transfer belt  7  are collectively transferred (secondarily transferred) onto the surface of the conveyed sheet S. 
   The sheet S having the developer images transferred thereon is sent to a fixing device  14 . The sheet S is heated and pressed in the fixing device  14 . Then, the developer images are fixed on the sheet S. Consequently, an image is formed on the sheet S. After that, the sheet S is discharged from the fixing device  14  to a discharge portion of an upper cover  15  in an upper part of the image forming apparatus. 
   An operation for mounting and detaching the developing cartridges  5   a  to  5   d  and the process cartridge  30  will be described with reference to  FIG. 1 . 
   The operation for mounting and detaching the developing cartridges is the same for all the developing cartridges  5   a  to  5   d . Therefore, the operation for mounting and detaching the yellow developing cartridge  5   a  is described. When the cartridge  5   a  is taken out from the apparatus main body A, the cartridge  5   a  is rotated and moved by the rotary  1  to a mounting and detaching position  18 Y (position illustrated in  FIG. 1 ) different from the developing position  18 X illustrated in  FIG. 2 . At this point, none of the developing cartridges  5  is present in the developing position  18 X. When the cartridge  5   a  is mounted and detached in this state, the operator opens an open-closable cartridge door  16 . This enables the operator to remove the cartridge  5   a  from the rotary  1  and take out the cartridge  5   a  from the apparatus main body A. It should be noted that the door  16  is pivotable with respect to the apparatus main body A around a fulcrum  16   a . In  FIG. 1 , an open state of the door  16  is indicated by a broken line and a closed state of the door  16  is indicated by a solid line. The cartridge  5   a  is detachably mountable in an arrow X direction, and the taken-out cartridge  5   a  is indicated by a broken line. The mounting and detaching position  18 Y is a position where the cartridge  5   a  is opposed to the door  16 . In addition, the developing position  18 X is a position where the cartridge  5   a  is opposed to the photosensitive drum  2 . 
   Moreover, it is also possible to take out the process cartridge  30  from the apparatus main body A by opening the door  16  as described above ( FIG. 1 ). It should be noted that the cartridge  30  is detachably mountable in an arrow B direction. The taken-out cartridge  30  is indicated by a broken line ( FIG. 1 ). 
   In the structure described above, it is possible to mount and detach any cartridges  5   a  to  5   d  and  30  from the apparatus main body A independently from one another through one opening  16   b  of the apparatus main body A by opening the door  16 . 
   A state of the cartridge  30  mounted on the apparatus main body A will be described with reference to  FIGS. 3 and 4 .  FIG. 3  is a front view illustrating a state of the cartridge  30  mounted on the apparatus main body A.  FIG. 4  is a sectional view illustrating the state of the cartridge  30  mounted on the apparatus main body A. It should be noted that  FIG. 8  is a sectional view illustrating a state of mounting the cartridge  30  on the apparatus main body A. And,  FIG. 9  is a perspective view illustrating the state of mounting the cartridge to the apparatus main body A. 
   As illustrated in  FIG. 3 , lock portions  33  that lock the cartridge  30  with the apparatus main body A when the cartridge  30  is mounted on the apparatus main body A are provided at both ends (one end  30   a  and the other end  30   b ) in a longitudinal direction of the cartridge  30 . The lock portions  33  are integrally provided in a frame  30   c  of the cartridge  30 . In other words, the lock portions  33  are provided on an outer surface of a side  30   d  provided at the one end  30   a  in the longitudinal direction of the frame  30   c  and an outer surface of a side  30   e  provided at the other end  30   b  in the longitudinal direction. The respective lock portions  33  are locked in cut-out portions  34 , which are provided in both side plates (main body frame)  32  provided in the apparatus main body A, respectively, in the state of the cartridge  30  mounted on the apparatus main body A. In other words, the lock portions  33  have attached portions  33   a  attached to the sides ( 30   d  and  30   e ) and engaging portions  33   b  opposed to the attached portions  33   a  with gaps G therebetween. In addition, the lock portions  33  have supported portions  33   c  that connect the attached portions  33   a  and the engaging portions  33   b  with gaps therebetween. And, the lock portions  33  bilaterally constrain and lock the side plates  32  in the longitudinal direction. In other words, the lock portions  33  lock the side plates  32  with the side plates  32  constrained by the attached portions  33   a  and the engaging portions  33   b . Specifically, the supported portions  33   c  are supported by upper edges  34   a  of the cut-out portions  34  of the side plates  32  with inner side portions  32   a  of the side plates  32  constrained by the attached portions  33   a  and with outer portions  32   b  of the side plates  32  constrained by the engaging portions  33   b  ( FIGS. 3 and 9 ). In this state, the one end  30   a  of the cartridge  30  is supported by the side plate  32   a  on the one end side and the other end  30   b  of the cartridge  30  is supported by the side plate  32  on the other end side, whereby the cartridge  30  is detachably mounted on the apparatus main body A. In this state, the side plate  32  on the one end side and the side plate  32  on the other end side are locked following the cartridge  30  at both of the ends in the longitudinal direction of the cartridge  30 . 
   In other words, when the side plates  32  undergo a deflection to the inner side of the apparatus main body A, the attached portions  33   a  urge the inner side portions  32   a  of the side plates  32  to the outside and the lock portions  33  lock to the side plates  32 . And, when the side plates  32  undergo a deflection to the outer side of the apparatus main body A, the lock portions  33   b  urge the outer side portions  32   b  of the side plates  32  to the inside and the lock portions  33  lock to the side plates  32 . 
   In this way, the cartridge  30  corrects the deflection of the side plates  32  and maintains a distance between both of the side plates  32 . According to this embodiment described above, the one end side lock portion  33  provided on the one end side of the cartridge  30  bilaterally constrains and locks the one end side plate  32  in the longitudinal direction. And, the other end side lock portion  33  provided on the other end side of the cartridge  30  bilaterally constrains and locks the other end side plate  32  in the longitudinal direction. 
   Therefore, the cartridge  30  can ensure the distance between both of the side plates  32 . In other words, the cartridge  30  can regulate the distance between both of the side plates  32 . It should be noted that, specifically, the gaps G are set slightly larger than the thickness of the side plates  32 , taking into account a manufacturing tolerance. In this embodiment, a material of the side plates  32  is zinc-coated steel or a material similar thereto. In addition, the thickness of the side plates  32  is about 0.6 mm. On the other hand, the gaps G are about 0.65 mm. It should be noted that the width of the side plates  32  is about 300 mm and the height of the side plates  32  is about 220 mm. In addition, the thickness of conventional side plates is 1.0 mm to 0.8 mm. According to this embodiment, the thickness of the side plates  32  can be set smaller than the thickness of the conventional side plates by about 0.2 mm. In other words, according to this embodiment, since the thickness is small, even if the side plates  32  tilt to the inner side or the outer side of the apparatus main body A, accuracy of the distance between both of the side plates  32  can be maintained by the cartridge  30 . In addition, the cartridge  30  can achieve a function of reinforcing the side plates  32 . It should be noted that the weight of the cartridge  30  used in this embodiment is about 500 g. 
   It should be noted that the present invention is not limited to this embodiment. The numerical values and the materials described above are only examples. Numerical values and materials can be selected as appropriate. 
   A bottom plate  60  connects the side plates  32  on a lower side. In other words, the side plates  32  are vertically (substantially vertically) attached to the bottom plate  60 . A top plate (not shown) that connects an upper side of the side plates  32  is also provided. 
   This embodiment is effective when the side plates  32  undergo a deflection (cause positional deviation) even if, for example, the bottom plate, the top plate, or a stay (not shown) that connects both of the side plates  32  is provided. 
   According to this embodiment, the distance between both of the side plates  32  is regulated by the cartridge  30 . Therefore, the frame  30   c  of the cartridge  30  according to this embodiment is made of polystyrene with the thickness of 1.5 mm to 2.5 mm Consequently, the cartridge  30  has sufficient rigidity. It should be noted that the rigidity of the frame  30   c  can be realized not only by the thickness but also by, for example, forming ribs in the frame  30   c  or by attaching a metal reinforcing member such as an iron plate to the frame  30   c . Therefore, the thickness described above is an example only. The thickness of the frame  30   c  described above is not limited to this. 
   Hereinafter, description will be given with reference to  FIG. 10   
   According to this embodiment, the lock portions  33  may have tapers in surfaces ( 33   e  and  33   f ), which constrain the side plates  32 , in a mounding direction of the cartridge  30  (an arrow D direction of  FIG. 4 ). The tapers are provided to easily constrain and lock the side plates  32  with the lock portions  33  even if the side plates  32  are deviated from desired positions with respect to the lock portions  33  when the cartridge  30  is mounted on the apparatus main body A. 
   As described above, according to this embodiment, the lock portions  33  have the tapers in the attached portions  33   a  and the engaging portions  33   b . In other words, in the attached portions  33   a  and the engaging portions  33   b , tapers  33   h  and  33   i  inclined in a direction away from the side plates  32  from an upstream side to a downstream side are provided in the mounting direction D ( FIG. 10 ). When the thickness of the side plates  32  is about 0.6 mm, the length of l 1  and l 2  is about 1.5 mm. It should be noted that the thickness is only an example, so the thickness of the side plates  32  is not limited to this. Even if the side plates  32  and the lock portions  33  deviate from each other in a direction orthogonal to the mounting direction D when the cartridge  30  is mounted on the apparatus main body A, it is possible to surely guide the lock portions  33  to the side plates  32  using the tapers  33   h  and  33   i . This is effective when the side plates  32  undergo a deflection and are deviated from the desired positions. It should be noted that an angle of inclination of the tapers  33   h  and  33   i  with respect to the side plates  32  is about 30° (α 1  and α 2  of  FIG. 10 ). 
   As illustrated in  FIGS. 4 and 9 , a drum positioning portion  35  is provided in the apparatus main body A to position a part of the frame  30   c  of the cartridge  30  (near one end and the other end in the longitudinal direction of the photosensitive drum  2 ) with respect to the apparatus main body A. And, positioned portions  2   b  are provided at one end and the other end in the longitudinal direction of the cartridge  30  (the same as the longitudinal direction of the drum  2 ). The positioned portions  2   b  project outward from the sides  30   d  and  30   e  of the frame  30   c  and are provided on the same axis line as a drum axis  2   a  of the drum  2 . The positioned portions  2   b  are positioned by the positioning portion  35  with the cartridge  30  mounted on the apparatus main body A ( FIG. 4 ). 
   Moreover, as illustrated in  FIGS. 3 and 4 , lock levers  36  for fixing the cartridge  30  positioned and held in the apparatus main body A are provided in the apparatus main body A. As illustrated in  FIG. 4 , the vicinities of both of the ends in the longitudinal direction of the drum  2  are positioned by the positioning portion  35  and the lock portions  33  lock to the side plates  32 . In this state, the levers  36  are rotated in an arrow C direction ( FIG. 3 ). Consequently, the fixing of the cartridge  30  is completed with the cartridge  30  positioned and held in the apparatus main body A. It should be noted that the cartridge  30  in this state is urged by elastic means (not shown) provided in the apparatus main body A. Consequently, the cartridge  30  is surely positioned in the apparatus main body A. It should be noted that the operator manually operates the levers  36 . 
   As described above, according to this embodiment, by mounting the cartridge  30  on the apparatus main body A, the lock portions  33  of the cartridge  30  lock both of the side plates  32 . In this state, both of the side plates  32  are locked following the cartridge  30  at both of the ends in the longitudinal direction of the cartridge  30 . In other words, the side plates  32  undergo a deflection and follow the cartridge  30 . Consequently, the cartridge  30  mounted on the apparatus main body A regulates the distance between both of the side plates  32 . At the same time, the cartridge  30  also functions as a reinforcing member for securing the rigidity of the apparatus main body A. Therefore, the thickness of the side plates  32  is reduced or the material of the side plates  32  is changed to a low-cost material. Consequently, even if a reduction in cost and a reduction in size of the apparatus main body A are realized, operability for mounting and detaching the cartridge  30  to and from the apparatus main body A is not deteriorated. Further, it is possible to accurately position and stably hold the photosensitive drum  2  (the cartridge  30 ) with respect to the apparatus main body A. 
   According to this embodiment described above, the apparatus main body A has the side plate  32  (the one end side main body frame) that supports the one end side in the longitudinal direction of the cartridge  30  mounted on the apparatus main body A (the longitudinal direction of the photosensitive drum  2 ) and undergoes a deflection in the longitudinal direction. And, the apparatus main body A also has the side plate  32  (the other end side main body frame) that supports the other end side in the longitudinal direction of the cartridge  30  mounted on the apparatus main body A and undergoes a deflection in the longitudinal direction. Under this condition, the cartridge  30  regulates the distance between the one end side plate  32  and the other end side plate  32  with the one end side in the longitudinal direction of the cartridge  30  supported by the side plate  32  and the other end side in the longitudinal direction thereof supported by the side plate  32 . 
   Second Embodiment 
   A second embodiment of the present invention is described with reference to  FIGS. 5 and 6 .  FIG. 5  is a front view illustrating a state of the cartridge  30  mounted on the apparatus main body A.  FIG. 6  is a sectional view illustrating the state of the cartridge  30  mounted on the apparatus main body A and is a sectional view along E-E of  FIG. 5 .  FIG. 11  is a side view illustrating a state of mounting the cartridge  30  to the apparatus main body A.  FIG. 12  is a perspective view illustrating the state of mounting the cartridge  30  to the apparatus main body A. 
   In this embodiment, unlike the first embodiment, the cartridge  30  does not directly lock both of the side plates  32  but indirectly locks both of the side plates  32 . 
   As illustrated in  FIGS. 5 and 6 , guide members  37  are integrally provided in both of the side plates (main body frames)  32  provided in the apparatus main body A, respectively. And, the guide members  37  are made of resin. The guide members  37  have guide surfaces  38  that guide the cartridge  30  when the cartridge  30  is mounted on the apparatus main body A and abutting surfaces  39  for regulating a position in an inserting direction of the cartridge  30 . Further, the guide members  37  have cut-out portions  34  for constraining and locking the lock portions  33  of the cartridge  30 . As illustrated in  FIG. 5 , the lock portions  33  of the cartridge  30  are bilaterally constrained and locked in the longitudinal direction by concave portions  40  of the guide members  37 , respectively. In this state, both of the side plates  32  are locked following the cartridge  30  at both of the ends in the longitudinal direction of the cartridge  30 . In other words, the side plates  32  undergo a deflection and follow the cartridge  30 . Therefore, the cartridge  30  can guarantee the distance between both of the side plates  32 . 
   As described above, according to this embodiment, the lock portions  33  are provided to project outward in the longitudinal direction from the sides  30   d  and  30   e . And, the lock portions  33  have the attached portions  33   a  provided along the sides  30   d  and  30   e  (parallel to the sides  30   d  and  30   e ) with the gaps G therebetween. And, the lock portions  33  also have supported portions  41  that are provided to project in the longitudinal direction from the sides  30   d  and  30   e  and support the attached portions  33   a  on the sides  30   d  and  30   e . A size of the gaps G and a size of the side plates  32  are as described above. 
   On the other hand, the guide members  37  have the concave portions  40  in the inner side portions  32   a  of the side plates  32 . The concave portions  40  support the attached portions  33   a . In other words, the attached portions  33   a  enter and fit in the concave portions  40 . And, the attached portions  33   a  are supported by the concave portions  40 . In other words, when the side plates  32  undergo a deflection to the inner side of the apparatus main body A, the outer side surfaces  33   f  of the attached portions  33   a  urge outer side inner surfaces  40   a  of the concave portions  40  to the outer side and the lock portions  33  lock to the side plates  32 . And, when the side plates  32  undergo a deflection to the outer side of the apparatus main body A, the inner side surfaces  33   g  of the attached portions  33   a  urge inner side inner surfaces  40   b  of the concave portions  40  to the inner side and the lock portions  33  lock to the side plates  32 . It should be noted that, in this state, wall portion distal ends  40   c  of the concave portions  40  support the supported portions  41 . 
   According to this embodiment, the one end side lock portion  33  provided on one end side of the cartridge  30  is constrained and locked by the one end side guide member  37  provided in the one end side plate  32  in the longitudinal direction. And, the other end side lock portion  33  provided on the other end side of the cartridge  30  is constrained and locked by the other end side guide member  37  provided in the other end side plate  32  in the longitudinal direction. 
   In this way, the cartridge  30  corrects the deflection of the side plates  32  and maintains the distance between both of the side plates  32 . In other words, the cartridge  30  corrects the deflection of the side plates  32  and regulates the distance between both of the side plates  32 . 
   The other components in this embodiment are the same as those in the first embodiment. Therefore, description of the components is omitted. 
   As described above, according to this embodiment, by mounting the cartridge  30  to the apparatus main body A, the lock portions  33  of the cartridge  30  are locked by the guide members  37  provided in the apparatus main body A. In this case, the guide members  37  are locked following the cartridge  30  at both of the ends in the longitudinal direction of the cartridge  30 . Consequently, the cartridge  30  mounted on the apparatus main body A regulates a distance between the guide members  37 . At the same time, the cartridge  30  also functions as a reinforcing member for securing rigidity of the apparatus main body A. Therefore, the thickness of the side plates  32  is reduced or the material of the side plates  32  is changed to a low-cost material. Consequently, even if a reduction in cost and a reduction in size of the apparatus main body A are realized, operability for mounting and detaching the cartridge  30  to and from the apparatus main body A is not deteriorated. Further, it is possible to accurately position and stably hold the photosensitive drum  2  with respect to the apparatus main body A. 
   Third Embodiment 
   A third embodiment of the present invention is described with reference to  FIG. 7 .  FIG. 7  is a perspective view illustrating a state of the cartridge  30  mounted on the apparatus main body A.  FIG. 13  is a diagram illustrating a structure of lock portions according to this embodiment. 
   In this embodiment, as described in the second embodiment, the cartridge  30  is indirectly locked to both of the side plates  32 . 
   As illustrated in  FIG. 7 , main body side positioning members  50  as guide members are integrally provided in both of the side plates  32 , respectively. In the main body side positioning members  50 , positioning holes (lock portions)  51  that fit with positioning pins (lock portions)  53  of the cartridge  30  and fixing screw holes  52  for fixing the cartridge  30  to the apparatus main body A with screws are provided. As illustrated in  FIG. 7 , the positioning pins  53  are inserted and fit in the positioning holes  51  of the positioning members  50  in a cartridge mounting direction orthogonal to the longitudinal direction, respectively. In this case, the side plates  32  are locked following the cartridge  30  at both of the ends in the longitudinal direction of the cartridge  30 . Therefore, the cartridge  30  guarantees the distance between both of the side plates  32 . 
   When the cartridge  30  mounted on the apparatus main body A is fixed to the apparatus main body A as described above, the screws  54  are fastened to the fixing screw holes  52  via the cartridge  30 . Consequently, the fixing of the cartridge  30  is completed with the cartridge  30  positioned and held in the apparatus main body A. An enlarged view of tapers  53   a  is illustrated in  FIG. 13 . Also, in this embodiment, the tapers  53   a  are provided at distal ends of the positioning pins  53  in the mounting direction D. An effect of the tapers  53   a  is the same as an effect of tapers  33   h  and  33   i  ( FIG. 10 ) described later. It should be noted that the length of l 1  and l 2  is about 1.5 mm. 
   The other components in this embodiment are the same as those in the embodiments described above. Therefore, description of the components is omitted. 
   As described above, according to this embodiment, by mounting the cartridge  30  to the apparatus main body A, the positioning portions  53  of the cartridge  30  fit in the positioning members  50  of the apparatus main body A. In this case, the positioning members  50  of the apparatus main body A fit following the cartridge  30  at both of the ends in the longitudinal direction of the cartridge  30 . 
   In this embodiment, tapers illustrated in  FIG. 13  may be provided. 
   In other words, the tapers  33   h  and  33   i  inclined in a direction away from the side plates  32  from an upstream side to a downstream side in the mounting direction D are provided in the attached portions  33   a  and the engaging portions  33   b  ( FIG. 10 ). When the thickness of the side plates  32  is about 0.6 mm, the length of l 1  and l 2  is about 1.5 mm. The thickness described above is only an example. The thickness of the side plates  32  is not limited to this. When the cartridge  30  is mounted on the apparatus main body A, even if the side plates  32  and the lock portions  33  deviate from each other in the direction orthogonal to the mounting direction D, it is possible to surely guide the lock portions  33  to the side plates  32  using the tapers  33   h  and  33   i . This is effective when the side plates  32  undergo a deflection and are deviated from the desired positions. It should be noted that an angle of inclination of the tapers  33   h  and  33   i  with respect to the side plates  32  is about 30° (α 1  and α 2  of  FIG. 10 ). Incidentally, a fitting portion  33   n  is guided by a tapered portion  33   h  and/or a tapered portion  33   i  so as to be fitted onto the side plate  32 . 
   According to this embodiment, the one end side positioning pin (the one side lock portion)  53  provided on one end side of the cartridge  30  is inserted and fit in the main body side positioning member (the one side guide member)  50  (the positioning hole (the lock portion)  51 ), which is provided in the one end side plate  32 , from the direction orthogonal to the longitudinal direction. And, the other end side positioning pin (the other end side lock portion)  53  provided on the other end side of the cartridge  30  is inserted and fit in the main body side positioning member (the other end side guide member)  50  (the positioning hole (the lock portion)  51 ), which is provided in the other end side plate  32 , from the direction orthogonal to the longitudinal direction. 
   Consequently, the cartridge  30  mounted on the apparatus main body A regulates a distance between the positioning members  50  of the apparatus main body A. In other words, the cartridge  30  regulates the distance between the side plates  32 . At the same time, the cartridge  30  also functions as a reinforcing member for securing rigidity of the apparatus main body A. Therefore, even if a reduction in cost and a reduction in size of the apparatus main body A are realized, operability for mounting and detaching the cartridge  30  to and from the apparatus main body A does not deteriorate. Further, it is possible to accurately position and stably hold the photosensitive drum  2  (cartridge  30 ) with respect to the apparatus main body A. Therefore, it is possible to prevent a mounting failure of the cartridge  3  and an image failure. 
   Other Embodiments 
   In the embodiments described above, the process cartridge is described as an example. However, the present invention is not limited to this. The same effect can be obtained when the present invention is applied to the developing cartridges  5   a  to  5   d  detachably mountable to the rotary  1 . Therefore, the present invention can be applied to developing cartridges in the same manner. 
   For example, in the same manner as the lock portions  33  of the cartridge  30  according to the first embodiment described above, lock portions that lock to both side plates forming a frame of a rotary are provided at both ends in a longitudinal direction of developing cartridges. The lock portions are integrally provided in frames of the developing cartridges. And, by mounting the developing cartridges to an apparatus main body, both of the side plates of the rotary are bilaterally constrained in the longitudinal direction and locked. In this case, the rotary is locked following the developing cartridges at both of the ends in the longitudinal direction of the developing cartridges. Therefore, the developing cartridges can guarantee the distance between both of the side plates of the rotary. 
   In the same manner as the guide members  37  of the apparatus main body A in the second embodiment described above, guide members are integrally provided in both side plates forming a frame of a rotary, respectively. The guide members are made of resin and have guide surfaces that guide developing cartridges when the developing cartridges are mounted on the rotary and abutting surfaces for regulating positions in an inserting direction of the developing cartridges. In addition, the guide members have cut-out portions for constraining and locking lock portions of the developing cartridges. The lock portions of the developing cartridges are bilaterally constrained and locked in the longitudinal direction by the cut-out portions of the guide members, respectively. In this case, the rotary is locked following the developing cartridges at both of the ends in the longitudinal direction of the developing cartridges. Therefore, the developing cartridges guarantee the distance between both of the side plates of the rotary. 
   In the same manner as the main body side positioning members  50  of the apparatus main body A in the third embodiment described above, positioning members (guide members) are integrally provided in both side plates forming a frame of a rotary, respectively. The positioning members have positioning holes (lock portions) that fit with positioning pins (lock portions) of developing cartridges and fixing screw holes for fixing the developing cartridges to an apparatus main body A with screws. The positioning pins of the developing cartridges are inserted and fit in the positioning holes of the positioning member in a cartridge mounting direction orthogonal to the longitudinal direction, respectively. In this case, the apparatus main body A (both of the side plates of the rotary) is locked following the developing cartridges at both ends in the longitudinal direction of the developing cartridges. Therefore, the developing cartridges guarantee the distance between both of the side plates of the rotary. 
   As described above, when the present invention is applied to the developing cartridges detachably mountable to the rotary of the image forming apparatus main body, it is possible to obtain an effect same as the effect of the process cartridge described above. 
   In the embodiments described above, the developing cartridges detachably mountable to the rotary of the apparatus main body are described as an example. However, the present invention is not limited to this. For example, when the present invention is applied to developing cartridges directly detachably mountable to an apparatus main body of an image forming apparatus that does not have the rotary, it is possible to obtain the same effect. 
   In the embodiments described above, the configuration of using the four developing cartridges is described as an example. However, the number of developing cartridges in use is not limited to this and may be appropriately set as required. 
   In the embodiments described above, as the process cartridge detachably mountable to the image forming apparatus main body, the cartridge integrally including the photosensitive drum, the charging means as a process member that acts on the photosensitive drum, and the cleaning means is described as an example. However, the process cartridge is not limited to this configuration. For example, the process cartridge may be a cartridge that integrally includes any one of charging means (a process member), developing means (a process member), and cleaning means (a process member), besides a photosensitive drum. 
   In the embodiments described above, the configuration of using one process cartridge is described as an example. However, the number of process cartridges in use is not limited to this and may be appropriately set as required. 
   As described above, the present invention can be applied to the process cartridge which integrally includes the photosensitive drum  2  and the process member, which acts on the photosensitive drum  2  and which is detachably mountable to the main body of the electrophotographic image forming apparatus. Further, the present invention can be applied to the developing cartridge that integrally includes the developing rollers  25  for developing electrostatic latent images formed on the photosensitive drum  2  and the developer containing portions which contain developers used for developing the electrostatic latent images by the developing rollers  25  and which is detachably mountable to the apparatus main body A. 
   In the embodiments described above, the printer is described as an example of the electrophotographic image forming apparatus. However, the present invention is not limited to this. For example, the electrophotographic image forming apparatus may be other electrophotographic image forming apparatuses such as a copying machine and a facsimile machine or may be other electrophotographic image forming apparatuses such as a multifunction peripheral in which functions of the copying machine, the facsimile machine, and the like are combined. In the embodiments described above, the electrophotographic image forming apparatus in which the intermediate transfer member is used is described as an example. However, the present invention is not limited to this. For example, the electrophotographic image forming apparatus may be an electrophotographic image forming apparatus in which a recording medium carrying member is used. In this electrophotographic image forming apparatus, developer images of respective colors are sequentially superimposed one on top of another and transferred onto a recording medium carried by the recording medium carrying member. It is possible to obtain the same effect by applying the present invention to such an image forming apparatus. 
   According to the embodiments described above, movement of the cartridges (developing cartridges  5 , process cartridge  30 ) and the one end side plate  32  in the longitudinal direction of the cartridges are regulated. Movement of the cartridges  5  and  30  and the other end side plate  32  in the longitudinal direction are regulated. In this state, the cartridges  5  and  30  are supported by the one end side plate  32  and the other end side plate  32 . Consequently, it is possible to obtain the effect described above. 
   According to the embodiments described above, by mounting the cartridge to the apparatus main body, the lock portions of the cartridge lock the apparatus main body. In this case, the apparatus main body is locked following the cartridge at both ends in the longitudinal direction of the cartridge. Consequently, the cartridge regulates the distance in the apparatus main body in which the cartridge mounted on the apparatus main body is interposed. At the same time, the cartridge also functions as a reinforcing member that secures rigidity of the apparatus main body. Therefore, even if a reduction in cost and a reduction in size of the apparatus main body are realized, operability for mounting and detaching the cartridge to and from the apparatus main body does not deteriorate. Further, it is possible, for example, to accurately position and stably hold the electrophotographic photosensitive drum with respect to the apparatus main body. 
   While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
   This application claims the benefit of Japanese Patent Application No. 2007-128987, filed May 15, 2007, and Japanese Patent Application No. 2008-112003, filed Apr. 23, 2008, which are hereby incorporated by reference herein in their entirety.