Abstract:
A developing cartridge detachably mountable to an electrophotographic image forming apparatus. The cartridge includes a frame, a developing roller, a frame groove, a frame projection, a bearing configured and positioned to rotatably support a developing roller shaft, a bearing cylinder, an elongated bearing opening receiving the frame projection, first and second bearing projections, first, second and third screws, a side cover covering the bearing and including a first opening engageable with the first bearing projection and a second opening engageable with the second bearing projection, and a side cover projection engageable with the bearing cylinder. The first screw secures the bearing to the frame, the second screw secures the side cover to the frame and the third screw secures the side cover to the first bearing projection.

Description:
FIELD OF THE INVENTION AND RELATED ART 
   The present invention relates to a development cartridge, an electrophotographic image forming apparatus in which a development cartridge is removably mountable, a method for attaching one of the two end covers of a development cartridge, and a method for attaching the other end cover of the development cartridge. 
   Here, an electrophotographic image forming apparatus means an apparatus for forming an image on a recording medium with using an electrophotographic image formation process. For example, it includes electrophotographic copying machines, electrophotographic printers (LED printers, laser beam printers, etc.), electrophotographic facsimile machines, electrophotographic wordprocessors, etc. 
   In the field of an image forming apparatus, a development cartridge system, that is, a system in which the developing members for developing an electrostatic latent image formed on the electrophotographic photoconductive member are disposed in a cartridge, which comprises a storage portion for storing developer (which hereinafter will be referred to as “toner”), and which is removably mountable in the main assembly of the image forming apparatus, has been widely employed. 
   The development cartridge system allows a user to maintain an image forming apparatus without relying on a service person, drastically improving an image forming apparatus in terms of operational efficiency. Thus, the cartridge system has been widely used in the field of an electrophotographic image forming apparatus. 
   Some of the development cartridges employed by a development cartridge system have been known to use side covers, which are attached to the lengthwise ends of the cartridge frame, one for one (U.S. Pat. No. 5,966,566). 
   SUMMARY OF THE INVENTION 
   The present invention is a further development of the prior art described above. 
   The primary object of the present invention is to provide a development cartridge superior to development cartridges in accordance with the prior art, in terms of the efficiency with which the side covers are attached to a cartridge frame, a method for attaching the side covers, and an electrophotographic image forming apparatus. 
   Another object of the present invention is to provide a development cartridge superior to development cartridges in accordance with the prior arts, in terms of the accuracy with which side covers are attached to a cartridge frame, a method for attaching the side covers, and an electrophotographic image forming apparatus. 
   Another object of the present invention is to provide a development cartridge superior to development cartridges in accordance with the prior art, in terms of how solidly the side covers are attached to a cartridge frame, a method for attaching the side covers, and an electrophotographic image forming apparatus. 
   Another object of the present invention is to provide a development cartridge, the side covers of which are reinforced by being attached to a cartridge frame, to prevent the side covers from deforming when the position of the development cartridge relative to the main assembly of an electrophotographic image forming apparatus is fixed by a part of each side cover when the development cartridge is mounted into the main assembly of the image forming apparatus, and thereafter, being therefore superior to development cartridges in accordance with the prior art, in terms of the accuracy with which the development cartridge is positioned relative to the main assembly of an electrophotographic image forming apparatus, a method for attaching the side covers, and an electrophotographic image forming apparatus. 
   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 sectional view of the main assembly of an electrophotographic color image forming apparatus in accordance with the present invention. 
       FIG. 2  is a sectional view of the main portion of a process cartridge mountable in an electrophotographic color image forming apparatus in accordance with the present invention. 
       FIG. 3  is a sectional view of the development cartridge in the first embodiment of the present invention. 
       FIG. 4  is a perspective view of the development cartridge in the first embodiment of the present invention. 
       FIG. 5  is a side view of the lengthwise end of the development cartridge, from which the development cartridge is driven. 
       FIG. 6  is a plan view of the development cartridge in  FIG. 4 , as seen front the photoconductive drum side. 
       FIG. 7  is a bottom view of the development cartridge in  FIG. 4 . 
       FIG. 8  is a perspective view of the partially exploded view of the development cartridge in  FIG. 4 , for showing how one of the side covers is attached. 
       FIG. 9  is a perspective view of the side covers shown in  FIG. 4 , for showing the outward side of the side cover. 
       FIG. 10  is a perspective view of the side cover in  FIG. 4 , for showing the inward side thereof. 
       FIG. 11  is a perspective view of a rotary device of the main assembly of the image forming apparatus, and one of the development cartridges, in the first embodiment of the present invention, for showing how the latter is mounted into the former. 
       FIG. 12  is a perspective view of the rotary disk, for showing the structure thereof for accommodating development cartridges. 
       FIG. 13  is a plan view of a development cartridge and one of the rotary discs, showing how the former is engaged with the latter. 
       FIG. 14  is a perspective view of the driving force transmission gear train for driving a development cartridge. 
       FIG. 15  is a drawing showing how the gear of a development cartridge meshes with the gear of the driving force transmission gear train as the development cartridge is moved into its development position. 
       FIG. 16  is a drawing showing the engagement between the gears of the development cartridge in its development position, and the gears of the driving force transmission gear train. 
       FIG. 17  is a perspective view of a part of the rotary device, on the side from which the rotary disk is not driven, showing in detail the connection between the electrical contact point on the main assembly side of the image forming apparatus and the electrical contact point on the development cartridge side, in the first embodiment of the present invention. 
       FIG. 18  is a sectional view of the rotary device, on the side from which the rotary disk is not driven, and the corresponding lengthwise end of a development cartridge, showing in detail how the development cartridge is positioned relative to the rotary disk in terms of the lengthwise direction of the development cartridge, and how the electrical contact point on the main assembly side is connected to the electrical contact point on the development cartridge side. 
       FIG. 19  is also a perspective view of a part of the rotary device, on the side from which the rotary device is not driven, and the corresponding lengthwise end of a development cartridge, showing in detail how the development cartridge is positioned relative to the rotary in terms of the lengthwise direction of the development cartridge, and how the electrical contact point on the main assembly side is connected to the electrical contact point on the development cartridge side. 
       FIG. 20  is a perspective view of the development cartridge in a second embodiment of the present invention. 
       FIG. 21  is a perspective view of one of the side covers of the development cartridge in  FIG. 20 , showing the outward side of the side cover. 
       FIG. 22  is a perspective view of the side cover in  FIG. 20 , showing the inward side thereof. 
       FIG. 23  is a sectional view of the lengthwise end of the rotary device, on the side from which the rotary device is not driven, and the corresponding lengthwise end of a development cartridge, in the second embodiment of the present invention, showing in detail, how the development cartridge is positioned relative to the rotary in terms of the lengthwise direction of the development cartridge, and how the electrical contact point on the main assembly side is connected to the electrical contact point on the development cartridge side. 
       FIG. 24  is a perspective view of one of the lengthwise ends of the cartridge frame, and one of the bearing members, showing how the bearing member is attached to the lengthwise end of the cartridge frame. 
       FIG. 25  is a perspective view of one of the lengthwise ends of the cartridge frame, and one of the side covers, showing how the side cover is attached to the lengthwise end of the cartridge frame. 
       FIG. 26  is a schematic drawing of the cartridge frame, bearing member, and side cover, showing how the bearing member and side cover are attached to the cartridge frame. 
       FIG. 27  is a perspective view of the other lengthwise end of the cartridge frame, and the corresponding bearing member, showing how the bearing member is attached to the cartridge frame. 
       FIG. 28  is a perspective view of the lengthwise end of the cartridge frame, shown in  FIG. 27 , and the corresponding side cover, showing how the side cover is attached to the cartridge frame. 
       FIG. 29  is a schematic drawing of the cartridge frame, bearing member, and side cover, showing how the bearing member and side cover are attached to the cartridge frame. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinafter, a development cartridge, an electrophotographic image forming apparatus, a method for attaching one of the side covers, and a method for attaching the other side cover, in accordance with the present invention, will be described in more detail with reference to the appended drawings. 
   Embodiment 1 
     FIG. 1  shows one of the preferred embodiments of an electrophotographic image forming apparatus, more specifically, a color laser beam printer, in accordance with the present invention. In the following description of this embodiment, the “front side” of the apparatus means the upstream side (right side in  FIG. 1 ) in terms of the direction in which recording medium (transfer medium) is conveyed from the transfer station to the fixation station. The “left or right side” of the main assembly of the apparatus means the left or right side as seen from the front side of the apparatus, and the “left or right side” of a process cartridge means the left or right side of the process cartridge as seen from the front side of the apparatus in the proper position in the main assembly of the apparatus. The “lengthwise direction” is the direction parallel to the surface of the recording medium in the apparatus, and is intersectional (virtually perpendicular) to the direction in which the recording medium is conveyed. 
   (General Structure of Electrophotographic Color Image Forming Apparatus) 
   First, the general structure of the electrophotographic color image forming apparatus A will be described with reference to  FIGS. 1 and 2 . 
   The color laser beam printer A in this embodiment comprises: four development cartridges  4 , more specifically, a yellow component developing device  4 Y, a magenta component developing device  4 M, a cyan component developing device  4 C, and a black component developing device  4 Bk; a process cartridge  5  comprising a photoconductive drum unit  20  and an intermediary transfer unit  21 ; and the main assembly  100  in which the development cartridges  4  and process cartridge  5  are removably mountable. 
   Referring to  FIG. 1 , in the image forming apparatus main assembly  100 , an optical image formed in accordance with image formation data is projected from an exposing means  3  to form an electrostatic latent image on a photoconductive drum  1  uniformly charged by a charging apparatus  2 . The formed latent image is developed into a visible image (which hereinafter may be referred to as “toner image”) by one of the development cartridges  4  which make up a part of a developing apparatus  4 A. The toner image is transferred onto an intermediary transfer member  5   a  by a first transferring means  5   j  as a transferring apparatus. 
   The toner image on the intermediary transfer member  5   a  is transferred by a second transferring means  11  onto a recording medium being conveyed by a conveying means in synchronism with the formation of the toner image. Then, the transfer medium is conveyed to a fixing means  8  comprising a pressure roller  8   a  and heat roller  8   b . In the fixing means  8 , the toner image on the transfer medium is permanently fixed to the transfer medium. Thereafter, the recording medium is discharged into a delivery tray  10 . 
   Next, referring to  FIG. 2 , in this embodiment, the photoconductive drum  1 , an intermediary transfer belt  5   a , and a waste toner box  216 , are integrated in the form of a process cartridge  5 , which is made up of two units: photoconductive drum unit  20  which contains the photoconductive drum  1 , and an intermediary transfer member unit  21  which contains the intermediary transfer belt  5   a  and waste toner box  216 . 
   The intermediary transfer belt unit  21  has a means (intermediary transferring means) for transferring a toner image from the photoconductive drum  1  onto a recording medium with the use of the intermediary transfer belt  5   a , and a means (waste toner recovering-storing means) for recovering the waste toner and storing it. 
   The intermediary transfer belt  5   a  is stretched around two rollers, which are a driver roller  240  and follower roller  241 . The process cartridge  5  has a primary transfer roller  5   j , which is disposed in a manner to oppose the photoconductive drum  1  with the intermediary transfer belt  5   a  interposed. 
   The process cartridge  5  also has a cleaning charge roller unit  223  for applying a predetermined amount of bias voltage to remove residual electrical charge from the residual toner, which in this case is the toner remaining on the intermediary transfer belt  5   a . The cleaning charge roller unit  223  is disposed in a manner to oppose the driver roller  240 . 
   The charge roller  5   f  of the cleaning charge roller unit  223  removes the residual electrical charge from the residual toner on the intermediary transfer belt  5   a  by applying the predetermined amount of bias voltage. After the removal of the residual electrical charge, the residual toner is electrostatically transferred back onto the photoconductive drum  1 . 
   Then, the residual toner is removed (recovered) by a cleaning blade  6 , and is accumulated in the waste toner box  216  as described before. 
   Referring again to  FIGS. 1 and 2 , the image formation process of the image forming apparatus structured as described above will be described in further detail. 
   The photoconductive drum  1  is rotated in the direction indicated by an arrow mark in  FIG. 1  (counterclockwise direction), in synchronism with the rotation of the intermediary transfer belt  5   a . As a predetermined charge bias voltage is applied to the charge roller  2  as a charging apparatus, the peripheral surface of the photoconductive drum  1  is uniformly charged. Then, the uniformly charged peripheral surface of the photoconductive drum  1  is exposed by an exposing means  3 ; it is exposed to the optical image, corresponding to, for example, the yellow component, of an intended image. As a result, an electrostatic latent image corresponding to the yellow component of the intended image is formed on the peripheral surface of the photoconductive drum  1 . 
   The exposing means  3  is a means for projecting a beam of light onto the peripheral surface of the photoconductive drum  1  while modulating the beam of light with the image formation information read through an external device or the like. The exposing means  3  comprises a laser diode, a polygon mirror, a scanner motor, a focusing lens, and a deflective mirror. 
   As image formation signals are given to the exposing means  3  from an external device or the like, the laser diode of the exposing means  3  emits a beam of light in response to the image formation signals. The emitted beam of light is projected as an image forming beam of light onto the polygon mirror, which is being rotated at a high speed by a scanner motor. As a result, the image forming beam of light is reflected by the polygon mirror, and is sent through the focusing lens. Then, it selectively exposes the peripheral surface of the photoconductive drum  1  after being reflected by the deflective mirror. Consequently, an electrostatic latent image is formed on the peripheral surface of the photoconductive drum  1 . 
   The electrostatic latent image on the photoconductive drum  1  is developed into an image formed of toner of a predetermined color (which hereinafter will be simply referred to as toner image). More specifically, the electrostatic latent image is developed by moving a predetermined development cartridge  4  among the four development cartridges  4  to the development position at which the predetermined component developing device opposes the photoconductive drum  1 . Incidentally, the four development cartridges  4  mounted in the rotary device  40  in this embodiment are a yellow component developing device  4 Y, a magenta component developing device  4 M, a cyan component developing device  4 C, and a black component developing device  4 Bk. 
   In other words, in this embodiment, as soon as an electrostatic latent image begins to be formed, the predetermined cartridge, for example, the yellow component developing device  4 Y, in the developing apparatus  4 A is orbitally moved into the development position. Then, a predetermined bias voltage is applied to adhere yellow toner to the electrostatic latent image to develop the electrostatic latent image. 
   Referring to  FIG. 3 , the development cartridge  4  can be roughly divided into two portions: a developer storage portion  302  as a toner container, and a development portion  301  which opposes the electrophotographic photoconductive drum  1 . The toner storage portion  302  and development portion  301  are integrally held by the cartridge frame  300 . 
   The toner storage portion  302  is filled with toner of a predetermined color, and is provided with a stirring means  303 . As the stirring means  303  is rotated, the toner is conveyed by a predetermined amount to the development portion  301 . In the development position  301 , the toner is supplied to the peripheral surface of the development roller  305  by the rotation of the toner supply roller  304  (developer supply roller) formed of sponge or like material. After being supplied to the peripheral surface of the development roller  305 , the toner is formed into a thin layer of toner by the development blade  332  in the form of a piece of thin plate, while being electrically charged by the friction between the toner and the development blade  332  as well as development roller  305 . As the development roller  305  is further rotated, the thin layer portion of the toner on the development roller  305  is conveyed to the development position  301 . In the development position  301 , the electrostatic latent image on the photoconductive drum  1  is developed by the application of a predetermined development bias. 
   The toner which did not contribute to the development of the latent image on the photoconductive drum  1 , that is, the toner which remained upused on the peripheral surface of the development roller  305 , is scraped away by the toner supply roller  304 . At the same time as the residual toner is scraped away by the toner supply roller  304 , a fresh supply of toner is supplied onto the development roller  305  by the toner supply roller  304  so that the development operation is continuously carried out by the freshly supplied portion of the toner on the development roller  305 . 
   Referring again to  FIGS. 1 and 2 , after being formed on the photoconductive drum  1 , the toner image (yellow toner image) is transferred (primary transfer) onto the intermediary transfer belt  5   a  by the application of bias voltage to a primary transfer roller  5   j , as a first transfer transferring means, that is, the roller for keeping the intermediary transfer belt  5   a  pressed upon the photoconductive drum  1 . The polarity of the bias voltage is opposite to that of the toner. 
   As the described above primary transfer of the yellow toner image ends, the next color component developing device, which in this embodiment is the magenta component developing device  4 M, is orbitally moved into the development position at which it opposes the photoconductive drum  1 . Then, the toner image of magenta color is transferred onto the intermediary transfer belt  5   a  through the same process as described above. This process is also carried out for the cyan and black color components. As a result, four toner images different in color are layered on the intermediary transfer belt  5   a.    
   While the four toner images are layered on the intermediary transfer belt  5   a , the secondary transfer roller  11  as a second transferring means, and a cleaning charge roller  5   f  as a cleaning unit, are kept separated from the intermediary transfer belt  5   a.    
   After the formation of the four toner images different in color on the intermediary transfer belt  5   a , the secondary transfer roller  11  is pressed upon the intermediary transfer belt  5   a  as shown in  FIG. 1 . In addition, in synchronism with the pressing of the secondary transfer roller  11  upon the intermediary transfer belt  5   a , a recording medium, which has been kept on standby at a predetermined location in the adjacencies of a pair of registration rollers  7  as a transfer medium conveying means, is sent to the nip between the intermediary transfer belt  5   a  and secondary transfer roller  11 . 
   The image forming apparatus is provided with a transfer medium sensor (front sensor)  14 , which is disposed on the immediately upstream side of the pair of registration rollers  7  in terms of the transfer medium conveyance direction. The sensor  14  detects the leading edge of the transfer medium, and as it detects the leading edge, it interrupts the conveyance of the force for rotationally driving the pair of registration rollers  7  to the pair of registration rollers  7  in order to keep the recording medium on standby at the predetermined location. 
   The secondary transfer roller  11  is provided with bias voltage opposite in polarity to the toner. Therefore, as a recording medium is conveyed through the nip, the toner images on the intermediary transfer belt  5   a  are transferred (secondary transfer) all at once onto the surface of the recording medium. 
   After the secondary transfer of the toner images, the recording medium is conveyed by way of a conveyer belt unit  12  to a fixing device  8 , in which the toner images are fixed. Thereafter, the transfer medium is further conveyed by a pair of discharge rollers  13  along a discharge guide  15 . Then, the transfer medium is discharged by a pair of discharge rollers  9  into a delivery tray  10  located on top of the color image forming apparatus A. This concludes the image formation. 
   Meanwhile, the cleaning charge roller  5   f  is pressed upon the intermediary transfer belt  5   a  after the secondary transfer. Then, the residual electrical charge is removed from the surface of the intermediary transfer belt  5   a  and the toner remaining on the intermediary transfer belt  5   a  after the secondary transfer is removed by the application of a predetermined bias voltage. 
   The residual toner, from which electrical charge has been removed, is electrostatically transferred from the intermediary transfer belt  5   a  onto the photoconductive drum  1 , in the primary transfer nip; in other words, the surface of the intermediary transfer belt  5   a  is cleaned. 
   The toner which remained on the intermediary transfer belt  5   a  after the secondary transfer and has been transferred back onto the photoconductive drum  1  is removed (recovered) from the photoconductive drum  1  by the cleaning blade  6 , is conveyed through a specified path (unshown), and is accumulated as waste toner in the waste toner box  216 . 
   (Rotary, Development Cartridge, and Developing Apparatus) 
   Next, referring to  FIGS. 4–13 , the development cartridge  4  and developing apparatus  4 A will be described. 
   The four development cartridges  4 , that is, yellow component developing device  4 Y, magenta component developing device  4 M, cyan component developing device  4 C, and black component developing device  4 Bk, which contain yellow, magenta, cyan, and black toners, one for one, are firmly mounted in their predesignated positions in the rotary device  40  of the developing apparatus  4 A, as previously described. 
   First, the method for positioning each development cartridge  4  relative to the rotary device  40  will be described. 
   Referring to  FIGS. 11–13 , the rotary device  40  is rotatable about the central axis  51 . It comprises the central axis  51 , and a pair of rotary disks  400  ( 400 A and  400 B) fixed to the lengthwise ends of the central axis  51 , one for one. 
   Rotary disks  400  ( 400 A and  400 B) are provided with: four guiding grooves  400   b  for guiding one of the development cartridges  4  when mounting or dismounting the development cartridge  4 ; four cartridge positioning grooves  400   h , against the bottom surface of which the development cartridge  4  is butted to be positioned relative to the rotary device  40  in terms of the lengthwise direction of the development cartridge  4 ; four positioning boss holding receptacles  400   d , each of which supports a development cartridge  4  by its positioning boss in a manner to allow the development cartridge  4  to pivot, and also function as cartridge positioning portions; and four V-shaped receptacle  400   e  for preventing the development cartridge  4  from rotating. 
   On the other hand, the development cartridge  4  is provided with first and second guides, which project from the left and right ends of the developing member (development roller)  305 ; in other words, the lengthwise ends of the development cartridge  4 , in terms of the lengthwise direction of the development cartridge  4 , one for one, as shown in  FIGS. 4 and 5 . Each of the first and second guides has a positioning boss  310   c , which is arcuate in cross section, and a flat guide rib  310   b . The boss  310   c  fits in one of the cartridge positioning groove  400   h , and corresponding receptacle  400   d , of the rotary disc  400  ( 400 A and  400 B). The guide rib  310   b  fits in one of the guiding grooves  400   b  of the rotary disc  400  ( 400 A and  400 B). 
   Further, the development cartridge  4  is provided with a pair of projections  310   m , which fit into the corresponding receptacles  400   e  of the rotary discs  400  ( 400 A and  400 B) to prevent the development cartridge  4  from rotating and also to precisely position the development cartridge  4  relative to the rotary device. The guide rib  310   b  is provided with a member with an electrical contact  311 A for development bias. The electric contact point  311  of the electrical contact  311 A, which is to be electrically connected to the electrical contact point  410  ( FIG. 17 ), on the main assembly side, for the development bias, is exposed from one of the lengthwise ends of the development cartridge, that is, from the guide rib  310   b , more specifically, at least from the top surface of the guide rib  310   b , which constitutes one of the endmost surfaces of the development cartridge  4  in terms of the lengthwise direction of the cartridge  4 . 
   Referring  FIG. 13 , the rotary discs  400  ( 400 A and  400 B) are provided with a spring  53  for keeping the development cartridge  4  pressured toward the counterclockwise direction of the drawing. The spring  53  is partially in the guiding groove  400   b , and is in contact with the pressure catching portion  310   k  of the bottom portion of the guiding rib  310   b . The development cartridge  4  is kept pressured in the direction to rotate about the boss  310   c , by the resiliency of the spring  53  and the moment generated by the force for rotationally driving the development roller  305 . The projections  310   m  of the development cartridge  4  are placed in contact with the receptacles  400   e  of the rotary discs  4000  ( 400 A and  400 B), one for one, with no gap. 
   Referring to  FIGS. 7 ,  11 ,  18 , etc., the development cartridge  4  in this embodiment is provided with a development cartridge locking portion  300   g . This cartridge locking portion  300   g  is allowed to freely move in the lengthwise direction of the development cartridge, in the long hole  310   q  formed in the lengthwise direction of the development cartridge  4  through the positioning boss  310   c . Normally, it is under such pressure that keeps it projecting outward. As the operational button  310   p  of the handle H of the development cartridge is pushed into the handle H, the cartridge locking portion  300   g  is retracted into the development cartridge. 
   In other words, as the development cartridge  4  is inserted into the rotary device  40 , the cartridge locking portion  300   g  fits into the cartridge locking hole  400   g  in the cartridge positioning groove  400   h  of the rotary disk  400  ( 400 A,  400 B). As a result, the development cartridge  4  is reliably retained in the position in which the cartridge locking portion  300   g  fits into the locking hole  400   g.    
   With the employment of the above described method for positioning the development cartridge  4 , the development cartridge  4  does not become disengaged from the rotary while the rotary device  40  is rotated. In order to remove the development cartridge  4  from the apparatus main assembly, the handle H located at the center of the top surface of the development cartridge  4  is to be grasped while pressing the operational button  310   p  inward of the handle H. With this action, the development cartridge  4  can be pulled out, upward from the rotary device  40  as shown in  FIG. 11 . 
   As described above, the development cartridge  4  is held between the two rotary discs  400  ( 400 A and  400 B) of the rotary device  40 , by the springs  53 , cartridge locking portions  300   g , etc., so that the development cartridge  4  can be easily mounted or dismounted. Thus, the development cartridge  4  can be easily mounted into, or dismounted from, the rotary  40 , in other words, the main assembly of an image forming apparatus, through a simple operation carried out by a user. 
   (Structures for Driving Rotary Device and Development Cartridge) 
   Next, referring to  FIGS. 14–17 , the structures for driving the rotary device  40  and development cartridge  4  will be described. 
   Each of the rotary disks  400  ( 400 A and  400 B) is provided with a rotary supporting plate  450 , which is on the outward side of the rotary disk  400 . The central axis  51  of the rotary device  40  is attached to the rotary disks  400  in such a manner that the central axis  51  penetrates both the rotary disks and rotary supporting plates  450 . In other words, the rotary disks  400  and central axis  51  are rotatably supported by the pair of rotary supporting plates  450 . 
   Next, referring  FIGS. 11 and 14 , the peripheral portion of each of the rotary disks  400  ( 400 A and  400 B) of the rotary device  40  constitutes a gear  308 . The two gear portions  308  are meshed with a pair of follower gears, one for one, located at the lengthwise ends of the rotary device  40 , although the follower gears are not shown. The two follower gears are connected by a rotational axis. Thus, as one of the rotary disk  400 , for example, the rotary disk  400 A, rotates, the other rotary disc, or the rotary disk  400 B, is rotated in synchronism with the rotary disk  400 A, by the follower gears. The gear portion  308  of one of the rotary disks, which in this embodiment is the gear portion  308  of the rotary disk  400 B, is connected to a rotary driving motor (unshown). 
   With the provision of the above described structure for driving the rotary device, the problem that one of the rotary disks  400  ( 400 A and  400 B) is twisted while the rotary disks  400  ( 400 A and  400 B) are rotated, or while the development roller is driven, is prevented. 
   Referring to  FIGS. 14 and 16 , one of the rotary supporting plates  450 , which in this embodiment is the rotary supporting plate  450  for the rotary disk  400 B, is provided with a plurality of gears  55  ( 55   a ,  55   b ,  55   c ,  55   d , and  55   e ). The input gear  307  of the development cartridge  4  is meshed with the most downstream gear  55   e  of the gear train (driving force transmission gear trains) attached to the rotary supporting plate  450 , and rotationally drives the development roller  305 , coating roller  304 , stirring member  303 , etc. 
   In this embodiment, as the rotary disks  400  rotate, the development cartridge  4  orbitally moves a predetermined angle about the rotational axes of the rotary disks  400 , causing its input gear  307  to mesh with the most downstream gear  55   e  of the gear train attached to the rotary supporting plate  450 . 
   Next, referring to  FIG. 15 , as the development cartridge  4  is orbitally moved in the direction indicated by an arrow mark R to the development position by the rotation of the rotary device  40 , the most downstream gear  55   e  of the gear train attached to the rotary supporting plate  450  meshes with the input gear  307  of the development cartridge  4 . 
   As the input gear  307  of the development cartridge  4  is driven by the most downstream gear  55   e  of the rotary supporting plate  450 , it is subjected to a force F directed as indicated by an arrow mark in  FIG. 16 . This force F (moment) acts in the direction to rotate the development cartridge  4  held in the grooves  400   d  of the rotary disks  400 , about the positioning bosses  310   c  of the development cartridge  4 , in the counterclockwise direction of the drawing. As a result, the projections  310   m  of the development cartridge  4  are kept pressed upon the V-shaped receptacles  400   e  of the rotary disks  400 , preventing thereby the development cartridge  4  from moving out of the predetermined development cartridge position in the rotary device  40  while the development cartridge  4  is driven in the development position. This force F is a part of the closed dynamical system within the rotary. Therefore, it has little effect upon the pressure W ( FIG. 15 ) applied to the photoconductive drum  1  by the development cartridge  4 . 
   The above described process for positioning the development cartridge can occur at both rotary disks  400  ( 400 A and  400 B) at the same time. 
   In this embodiment, however, the cartridge positioning process which occurs occur on the rotary disk  400 B side is made different from that on the rotary disk  400 A side. 
   More specifically, referring to  FIG. 5 , the size (diameter) of the positioning boss  310   c  on the rotary disk  400 B side of the development cartridge  4  is made smaller than that of the positioning receptacle  400   d  of the rotary disc  400 B in order to provide a predetermined amount of gap between the two. However, the positioning boss  310   c  is provided with a rib  310   s , which projects from a part of the peripheral surface of the positioning boss  310   c  so that it contacts the inward surface of the positioning receptacle  400   d.    
   With the provision of the above described structural arrangement, the positioning boss  310   c  of the development cartridge, on the rotary disk  400 A side, precisely fits in the positioning boss holding receptacle  400   d  of the rotary disk  400 A, and the projection  310   m  of the development cartridge contacts the V-shaped receptacle  400   e  of the rotary disk  400 A. As a result, the development cartridge  4  is highly precisely positioned. 
   On the other hand, on the rotary disk  400 B side, the positioning boss  310   c  of the development cartridge loosely fits in the positioning boss holding receptacle  400   d  of the rotary disk  400 B. However, as the development cartridge  4  begins to be driven by being moved to the development position, the development cartridge  4  is subjected to such force that presses the development cartridge  4  in the direction of the arrow mark. As a result, the projection  310   m  of the development cartridge fits into the V-shaped receptacle  400   e  of the rotary disc  400 A. In addition, the rib  310   s  projecting from a part of the peripheral surface of the positioning boss  310   c  comes into contact with the inward surface of the positioning boss holding receptacle  400   d . Therefore, the development cartridge  4  is accurately placed in the predetermined position. 
   Also in this embodiment, the development cartridge  4  is precisely positioned relative to the main assembly, more specifically, the rotary device  40 , of an image forming apparatus, by being moved to the development position. 
   (Method for Mounting Development Cartridge into Image Forming Apparatus) 
   Next, the structures of the guide ribs  310   b  of the development cartridge  4 , and the structure of the electrical contact of the development cartridge  4  for development bias, will be described. 
   Referring to  FIGS. 4–10 , in this embodiment, the lengthwise ends of the main structure of the development cartridge  4  are covered with side covers  310  ( 310 A and  310 B), one for one, which are separable from the main assembly of the development cartridge  4 .  FIG. 8  shows the development cartridge  4 , the side cover  310 A, that is, the left side cover in the drawing, which has been separated from the main assembly of the development cartridge. 
   Referring to  FIGS. 8–10 , the side cover  310 A is attached to the development cartridge main assembly in the following manner: First, the positioning hole  300   c  of the development cartridge main assembly (which hereinafter may be referred to “cartridge frame”) is to be aligned with the positioning boss  310   d   1  of the side cover  310 . Then, screws  330  and  331  are to be put through the holes  310   e  and  310   f  of the side cover  310 A, and then, are to be screwed into the holes  300   e  and  300   f  of the development cartridge main assembly, respectively. The side cover  310 B is attached to the development cartridge main assembly also with screws in the same manner as the side cover  310 A. 
   The development cartridge  4  is provided with the positioning bosses  310   c  for positioning the development cartridge  4 , and guide ribs  310   b  for guiding the development cartridge  4 . More specifically, each of the side covers  310  ( 310 A and  310 B) located at the lengthwise ends of the development cartridge main assembly, one for one, is provided with the positioning boss  310   c  and guide rib  310   b . Thus, as the positioning bosses  310   c  and guide ribs  310   b  of the development cartridge  4  are inserted into the corresponding cartridge positioning grooves  400   h , positioning boss holding receptacles  400   d , guiding grooves  400   b , etc., of the rotary disks  400  ( 400 A and  400 B), the development cartridge  4  is disposed in the predetermined position relative to the rotary disks  400  ( 400 A and  400 B), in other words, it is precisely disposed in the image forming apparatus main assembly. 
   The side cover  310 A of the development cartridge  4  is provided with the electrical contact  311 A for development bias, the contact point  311  of which is exposed from the top surface of the guide rib  310   b . As the development cartridge  4  is fixed in position by being moved into the development position, the electrical contact point  311  for the development bias, which will be described later in detail, becomes electrically connected to the electrical contact point  410  ( FIG. 19 ) for the development bias, on the apparatus main assembly side. 
   Referring to  FIG. 10 , in this embodiment, the development bias electrical contact  311 A having the development bias contact point  311  is wired so that as the side cover  310 A is attached to the development cartridge main assembly, the development bias electrical contact  311 A becomes connected to the developing member (development roller)  305  and developer coating member (toner supplying roller)  304  of the development cartridge  4 . With this structural arrangement, it is possible to apply both the development bias and coating member bias to the development roller  305  and toner supplying roller  304 , respectively. 
   The development bias contact point  311  is disposed on the guide rib  310   b . Therefore, as the development cartridge is mounted into the rotary device  40 , the contact point  311  is moved in the direction parallel to the direction in which the development cartridge is mounted. Further, the guide rib  310   b  is such a portion of the development cartridge  4  that guides the development cartridge  4  by being fitted in the cartridge guiding groove  400   b  of the rotary disk  400 , and the contact point  311  is exposed from the top surface of the guide rib  310   b . Therefore, the contact point  311  is guided in the same manner as the guide rib  310   b , assuring that the contact point  311  is precisely placed in a position in which it allows the development bias to be applied from the image forming apparatus main assembly. 
   Next, referring to  FIGS. 4 and 18 , the development cartridge  4  has a first projection  310   h  and a second projection  310   a . The first projection  310   h  is butted against the development bias electrical contact side of the image forming apparatus main assembly, in order to accurately position the development cartridge main assembly in terms of its lengthwise direction, and the second projection  310   a  is for regulating the movement of the development cartridge  4  in the direction opposite to the direction in which the development cartridge  4  is butted against the development bias electrical contact side of the image forming apparatus main assembly. These structural arrangements and the operations thereof will be described later. 
   Next, referring to  FIGS. 11 and 12 , the rotary device  40  and rotary disks  400  ( 400 A and  400 B) will be further described. 
     FIG. 11  shows how one of the development cartridges  4  is inserted into the rotary device  40 , and  FIG. 12  shows the details of the rotary disk  400 A, that is, the rotary disk  400  on the side from which the rotary device  40  is not driven. 
   Referring to  FIG. 12 , the rotary disk  400 A, on the side from which the rotary device  40  is not driven, has: a cartridge positioning groove  400   h  for assuring that the development bias electrical contact of the development cartridge  4  is placed in contact with the development bias electrical contact on the apparatus main assembly side; a positioning boss holding receptacle  400   d  for supporting the positioning boss  310   c  of the development cartridge  4 ; a groove  400   a  for regulating the movement of the development cartridge  4  in the direction opposite to the direction in which the development cartridge is butted against the development bias electrical contact side of the rotary device  40 ; a guiding groove  400   b , a hole  400   c  for allowing the development bias electrical contact  410  on the apparatus main assembly side to make contact with the development bias electrical contact on the development cartridge side; and a hole  400   g  into which a development cartridge position locking portion of the development cartridge  4  fits. 
   Referring to  FIG. 11 , the development cartridge  4  is to be inserted into the rotary device  40  with the guide portions  310   b  on the lengthwise ends of the development cartridge  4  aligned with the guiding grooves  400   b , one for one. After the insertion, the rotary device  40  is rotated so that the development cartridge  4  is moved to the location at which it comes into contact with the electrical contact point  410  attached to the supporting plate  450  of the rotary  40  shown in  FIG. 17 . 
     FIG. 15  shows the development cartridge  4  which has been locked into the predetermined position, that is, the development position. 
   While being kept in the above-described state, the development cartridge  4  is driven by the driving force from the image forming apparatus main assembly. As a result, the first projection  310   h  of the development cartridge  4  comes into contact with the cartridge positioning groove  400   h  of the rotary  40 , securing a predetermined distance between the development bias electrical contact point  410  of the apparatus main assembly and the development cartridge  4 , as shown in  FIGS. 18 and 19 . 
   In other words, as the development cartridge  4  is moved into the development position, the driving gear  55   e  on the apparatus main assembly side engages with the driving gear  307  of the development cartridge  4 , as shown in  FIG. 15 . As a result, the driving force is transmitted from the driving force input gear  307  to the development roller driving gear  305   a  through an idler gear  307   a  integral with the driving force input gear  307 , as shown in  FIG. 4 . 
   In this embodiment, the driving force input gear  307 , idler gear  307   a , and development roller driving gear  305   a  are helical gears, and the driving force input gear  307  is driven. With the provision of the above described structural arrangement, as the driving force is transmitted to the driving force input gear  307 , the development roller  305  and development cartridge  4  are pressed leftward in terms of the lengthwise direction of the development cartridge  4  in  FIGS. 4 and 11 . As a result, the first projection  310   h  of the development cartridge  4  comes into contact with the cartridge positioning groove  400   h  of the rotary device  40 , as shown in  FIG. 19 . 
   As for the movement off the development cartridge  4  in the opposite direction (rightward in  FIGS. 4 and 11 ) in terms of its lengthwise direction, the end surface of the second projection  310   a  attached to the development cartridge  4  makes contact with the bottom surface of the groove  400   a  of the rotary disk  400  of the image forming apparatus main assembly, regulating thereby the movement of the development cartridge in the aforementioned opposite direction in terms of its lengthwise direction. 
   In other words, the member  310   a  is provided for regulating the movement of the development cartridge  4  in the opposite direction even if the projection  310   h  of the development cartridge  4  fails to satisfactorily come into contact with the contact portion of the cartridge positioning groove  400   h  of the rotary device  40  due to irregularities in the driving of the development cartridge  4 . Therefore, the fluctuation of the distance between the development bias electrical contact point  410  of the image forming apparatus main assembly and the development bias electrical contact point  311  of the development cartridge  4  can be minimized. 
   In this embodiment, the development bias electrical contact point  410  is in the form of a coil spring, and is fixed to the supporting plate  450  of the rotary  40 , as shown in detail in  FIGS. 17  arid  19 . As the development cartridge  4  is moved to the predetermined position, the development bias electrical contact point  311  comes into contact with the development bias electrical contact point  410 . 
   The development bias electrical contact point  311  is attached to the guide rib  310   b  on the side from which the development cartridge  4  is not driven, and the first projection  310   h  for positioning the development cartridge  4 , the boss  310   c , and the guide rib  310   b  are integral. Therefore, the error in the distance between the first projection  310   h  for positioning the development cartridge  4  in terms of its lengthwise direction, and the development bias electrical contact point  311 , can be reduced to the error in the position of a single component resulting from the tolerance for the single component. 
   Further, as for the positional relationship between the development bias electrical contact point  410  of the image forming apparatus main assembly and the development bias electrical contact point  311  of the development cartridge  4 , there are only the rotary supporting plate  450 , development bias electrical contact point  410 , rotary device  40 , and the contact point  311  of the development cartridge  4 , in that order from the outward side of the rotary  40 . 
   In other words, the number of the components between the development bias electrical contact point  410  of the image forming apparatus main assembly and the development bias electrical contact point  311  of the development cartridge  4  is substantially smaller compared to that in accordance with the prior art; the overall error resulting from the sum of the tolerances of the components between the two development bias electrical contact points  410  and  311  can be minimized. In addition, the above described structural arrangement makes it easier to keep the predetermined distance between the two contact points. Therefore, the development bias can be reliably applied. 
   Further, the positioning of the development cartridge  4  in terms of its lengthwise direction, and the application of the development bias, are done on the rotary disk  400 A side, that is, the rotary disk on the side from which the development cartridge  4  is not driven, in other words, on the side opposite to the driving force input portion having the driving force input gear  307 . Therefore, the distance between the development bias electrical contact point  410  of the image forming apparatus main assembly and the development bias electrical contact point  311  of the development cartridge  4  is less likely to be affected by the minute displacement of the development cartridge  4  in its widthwise direction caused by the driving force; it is easier to keep the development bias electrical contact point  410  of the image forming apparatus main assembly and the development bias electrical contact point  311  of the development cartridge  4  at the predetermined locations. Therefore, it is possible to reliably apply the development bias. 
   Referring to  FIG. 9 , the electrical contact point  311  of the development cartridge  4  mounted in an electrophotographic image forming apparatus equipped with the rotary type developing apparatus  4 A is disposed on the guide rib  310   b  which is raised from the surfaces  310   i  and  310   j . Further, such a structural arrangement is made that the resinous portions of the development cartridge  4  neither intersect with the orbital path of the development bias electrical contact point  311  of the development cartridge  4  while the rotary device  40  is rotated, nor are they as high, from the surfaces  310   i  and  310   j , as the development bias electrical contact point  311 . With the provision of this structural arrangement, the bias voltage can be applied without damaging the resinous portion of the development cartridge  4 . Further, referring to  FIG. 18 , the top surface of the guide rib  310   b  is recessed inward of the development cartridge  4  by a distance E from the end surface of the projection  310   h  for regulating the position of the development cartridge  4  in its lengthwise direction. 
   Also with the provision of the above-described structural arrangement, it is unnecessary to provide the surfaces  310   i  and  310   j  of the development cartridge  4  with a portion, in addition to the guide rib  310   b , higher than the surfaces  310   i  and  310   j , in order to attach the development bias electrical contact point  311 . Therefore, it is possible to save space. Further, the surfaces  310   i  and  310   j  have nothing which hangs up when inserting the development cartridge. Therefore, the development cartridge can be smoothly inserted, improving the development cartridge in terms of the efficiency with which the development cartridge is mounted or dismounted. 
   As described above, in this embodiment, the development cartridge  4  is provided with the second projection for regulating the movement of the development cartridge  4  in the direction opposite to the location of the first projection  310   h  for positioning the development cartridge  4  in its lengthwise direction, whereas the rotary device  40  of the image forming apparatus main assembly is provided with the regulation groove  400   a  for regulating the movement of the development cartridge  4  in the direction opposite to the cartridge positioning groove  400   h . With the provision of this structural arrangement, it is easier to keep constant the distance between the development bias electrical contact point  410  and development bias electrical contact point  311 , making it possible to reliably apply the development bias voltage. 
   Also in this embodiment, the position of the development cartridge  4  in its lengthwise direction, and the application of the development bias, are accomplished from the side from which the development cartridge  4  is not driven, that is, from the side apart from the portion of the development cartridge  4  through which the driving force is inputted into the development cartridge  4 . Therefore, the positioning of the development cartridge  4  and application of the development bias are less likely to be affected by the displacement of the development cartridge  4  in the widthwise direction of the development cartridge  4  by the driving force, making it possible to reliably apply the development bias. 
   Also in this embodiment, the development bias electrical contact point  311  is attached to the guide rib  310   b  of the development cartridge  4 . Therefore, the resinous portion of the development cartridge  4  in the adjacencies of the electrical contact point  311  is not damaged when the rotary device  40  is rotated. Therefore, it is unnecessary to set up the development bias electrical contact point  311  one step higher than the surfaces  310   i  and  310   j  of the development cartridge  4 ; it is possible to reduce the development cartridge  4  in size. Also with the above described structural arrangement, the development cartridge  4  has no portion which hangs up when mounting or dismounting the development cartridge  4 . Therefore, it is possible to smoothly mount or dismount the development cartridge  4 , improving the efficiency with which the development cartridge  4  is operated by a user. 
   Embodiment 2 
     FIGS. 20–23  show the second embodiment of a development cartridge  4  in accordance with the present invention. 
   The general structure of the development cartridge  4  in this embodiment is the same as that in the first embodiment, except that in this embodiment, a pair of development bias contacts  311 A and  312 A are attached to the guide rib  310   b  on one of the lengthwise end surfaces of the development cartridge  4 . Thus, the components, members, etc., in this embodiment, which are similar in structure and function to those in the first embodiment described above, are given the same reference numbers as those given in the first embodiment, and their detailed descriptions will not be given. 
   In other words, also in this embodiment, the lengthwise end surface, on the side from which the development cartridge  4  is not driven, of the development cartridge  4 , that is, the outward surface of the side cover  310 A, is provided with: the first projection  310   h  for positioning the development cartridge  4  in its lengthwise direction; cartridge positioning boss  310   c ; second projection  310   a  for regulating the movement of the development cartridge  4  in the direction opposite to the direction in which the development cartridge  4  is pressed in terms of its lengthwise direction; and guide rib  310   b  for guiding the development cartridge  4  to the predetermined position when inserting the development cartridge  4 , as in the first embodiment. In this embodiment, however, the guide rib  310   b  is provided with the pair of development bias electrical contacts  311 A and  312 A, which are disposed so that the development bias electrical contact points  311  and  312  are exposed at least from the top surface of the guide rib  310   b.    
   These development bias electrical contact points  311  and  312  are electrically connected to the development bias electrical contact points  410  and  411  ( FIG. 23 ) of the image forming apparatus main assembly, as the development cartridge  4  is moved into the development position. 
   Referring to  FIG. 22 , in this embodiment, the development bias electrical contact  311 A having the development bias electrical contact point  311  is wired so that as the side cover  310 A is attached to the development cartridge main assembly, the development bias electrical contact  311 A becomes connected to the developing member (development roller)  305  and developer coating member (toner supplying roller)  304  of the development cartridge  4 . With this structural arrangement, it is possible to apply the development bias and coating member bias to the development roller  305  and toner supplying roller  304 , respectively. The development bias electrical contact  312 A having the development bias electrical contact point  312  is wired so that as the side cover  310 A is attached to the development cartridge main assembly, the development bias electrical contact  312 A becomes electrically connected to the developer amount regulating member (development blade)  332  of the development cartridge  4 . With this structural arrangement, it is possible to apply the developer amount regulating bias voltage to the development blade  332 . 
   The structure of the lengthwise end surface, on the side from which the development cartridge  4  is driven, of the development cartridge  4 , that is, the outward surface of the side cover  310 B, is the same as that in the first embodiment shown in  FIG. 5 . 
   In order to assure that the development cartridge  4  is mounted in the predetermined position, the end guide  310   b   1  is given a length equal to approximately half the radius of the arcuate surface of the development cartridge  4 . In other words, the end guide  310   b   1  is long enough for a plurality of electrical contact points to be attached to the end guide  310   b   1 . Therefore, the plurality of electrical contact points can be attached to the end guide  310   b   1  so that all of the plurality of electrical contact points are positioned at the same level. Therefore, it is possible to keep the contact pressure stable. 
   The operation for inserting the development cartridge  4  in this embodiment into the rotary device  40  is the same as that for inserting the development cartridge  4  in the first embodiment into the rotary  40 . 
   Next, referring to  FIG. 15  which is a sectional view of the development cartridge  4  having been locked into the predetermined position, as the development cartridge  4  is driven by the force from the image forming apparatus main assembly, the first projection  310   h  of the development cartridge  4  comes into contact with the cartridge positioning groove  400   h  of the rotary device  40 . As a result, a predetermined distance is secured between the development bias electrical contact points  410  and  411  of the image forming apparatus main assembly and the development cartridge  4 . 
   On the other hand, the lengthwise movement of the development cartridge  4  in the direction opposite to the direction in which the development cartridge  4  is pressed as the development cartridge  4  is driven is regulated as the end surface of the second projection  310   a  attached to the development cartridge  4  comes into contact with the bottom surface of the development cartridge movement regulating groove  400   a  of the rotary disk  400  of the image forming apparatus main assembly. 
   In other words, also in this embodiment, the member  400   a  for regulating the movement of the development cartridge  4  in the direction opposite to the direction in which the development cartridge  4  is pressed as the development cartridge  4  is driven, is provided for regulating the movement of the development cartridge  4  when the first projection  310   h  of the development cartridge  4  fails to satisfactorily come into contact with the cartridge positioning groove  400   h  of the rotary  40  because of irregularities in the driving of the development cartridge  4 . Therefore, the fluctuation of the distances between the development bias electrical contact points  410  and  411  of the image forming apparatus main assembly and the development bias electrical contact points  311  and  312 , respectively, of the development cartridge  4  can be reduced. 
   Further, the two development bias electrical contact points  410  and  411  of the image forming apparatus main assembly, more specifically, the supporting plate  450  of the rotary device  40  are in the form of a coil spring, and the contacts  410  and  411  are fixed to the supporting plate  450  of the rotary device  40 . 
   To these two development bias electrical contact points  410  and  411  of the image forming apparatus main assembly, the development bias electrical contact points  311  and  312  of the development cartridge  4  are electrically connected. 
   The development bias electrical contact points  311  and  312  are attached to the end guide  310   b   2  on the side from which the development cartridge  4  is not driven, at the same heights from the base of the guide  310   b   2 . Therefore, the error in the distances between the positioning projection  310   h  and the contact points  311  and  312  can be limited to the variations in the position of a single component resulting from the tolerance of the single component. 
   The positional relationships between the development bias electrical contact points  410  and  411  and development bias electrical contact points  311  and  312 , respectively, are as follows: there are only the rotary supporting plate  450 , development bias electrical contact point  410 , rotary device  40 , and the contact point  311  of the development cartridge  4 , in that order from the outward side of the rotary  40 . 
   Therefore, the number of the components between the pair of development bias electrical contact points  410  and  411  and the pair of development bias electrical contact points  311  and  312  is substantially smaller compared to that in accordance with the prior art; the overall error in positional relationship resulting from the sum of the tolerances of the components between the pair of development bias electrical contact points  410  and  411  and the pair of development bias electrical contact points  311  and  312 , respectively, can be minimized. Therefore, it is easier to keep a predetermined distance between the two pairs of contact points. Therefore, the development bias can be reliably applied. 
   Further, the positioning of the development cartridge  4  in its lengthwise direction, and the application of the development bias, are accomplished on the rotary disk  400 A side, that is, the side apart from the driving force input portion having the rotary disc on the side from which the development cartridge  4  is not driven, in other words, on the side opposite to the driving force input portion having the driving force input gear  307 . Therefore, the distances between the pair of development bias electrical contact points  410  and  411  and the pair of development bias electrical contact points  311  and  312 , respectively, are less likely to be affected by the minute displacement of the development cartridge  4  in its widthwise direction caused by the driving force; it is easier to keep the pair of development bias electrical contact points  410  and  411  and the pair of development bias electrical contact points  311  and  312  at the predetermined locations. Therefore, it is possible to reliably apply the development bias. 
   Further, in order to prevent the resinous portion of the development cartridge  4  in the adjacencies of the development bias electrical contact points  311  and  312  from being damaged, it is necessary to attach the development bias electrical contact points  311  and  312  to the portions of the development cartridge  4 , which is raised from the surfaces  310   i  and  310   j.    
   In this embodiment, therefore, the development bias electrical contact points  311  and  312  are attached to the top surface of the guide rib  310   b , which is located more outward from the main assembly of the development cartridge  4 , in the lengthwise direction of the development cartridge  4 , than the surfaces  310   i  and  310   j . Therefore, it is possible to eliminate the need for providing the surfaces  310   i  or  310   j  of the development cartridge  4  with an additional raised portion to which the development bias electrical contact points  311  and  312  are to be attached, contributing thereby to space saving. Further, without the additional raised portion on the surface  310   i  and/or  310   j , the surfaces  310   i  and  310   j  do not have such a portion that hangs up during the insertion of the development cartridge, making it possible to smoothly insert the development cartridge, improving in turn the efficiency and ease with which the development cartridge is mounted or dismounted by a user. 
   As described above, in this embodiment, the development cartridge  4  is provided with the positioning rib, whereas the rotary device  40  of the image forming apparatus main assembly is provided with the groove for positioning the development cartridge  4  in the lengthwise direction of the development cartridge  4 . Therefore, it can be made easier to keep constant the distances between the pair of development bias electrical contact points  410  and  411  and the pair of development bias electrical contact points  311  and  312 , respectively. Therefore, the development bias can be reliably applied. 
   Also in this embodiment, the positioning of the development cartridge  4  in its lengthwise direction, and the application of the development bias, are accomplished from the side from which the development cartridge  4  is not driven, that is, from the side apart from the portion of the development cartridge  4  through which the driving force is inputted into the development cartridge  4 . Therefore, the positioning of the development cartridge  4  and application of the development bias are less likely to be affected by the displacement of the development cartridge  4  in the widthwise direction of the development cartridge  4  by the driving force, making it possible to reliably apply the development bias. Further, this embodiment makes it possible to dispose a plurality of development bias electrical contact points on the guide rib  310   b , at the same heights from the surface from which the guide rib  310   b  projects. Therefore, it is possible to equalize the plurality of development bias electrical contact points in terms of the pressure applied thereto, making it possible to reliably apply stable development bias. 
   Also in this embodiment, the development bias electrical contact points  311  and  312  are attached to the guide rib  310   b  of the development cartridge  4 . Therefore, the resinous portions of the development cartridge  4  in the adjacencies of the electrical contact points are not damaged when the rotary device  40  is rotated. Therefore, it is unnecessary to set up the development bias electrical contact points one step higher than the adjacencies of the contact points; it is possible to reduce the development cartridge  4  in size. Also with the above described structural arrangement, the development cartridge  4  does not have such a projecting portion that hangs up when mounting or dismounting the development cartridge  4 . Therefore, it is possible to smoothly mount or dismount the development cartridge  4 , improving the efficiency with the development cartridge  4  is operated by a user. 
   Referring to  FIGS. 4 and 20 , as is understood from the above description, according to the first and second embodiments of the present invention, the development cartridges  4  are provided with the positioning ribs, each of which is an integral combination of the guide rib  310   b  and positioning projection  310   h . Further, the portion  310   a  of the development cartridge  4  for regulating the position of the development cartridge  4  in the lengthwise direction of the development cartridge  4  is on the imaginary extension of the positional rib. In other words, the positioning portion  310   h , the guiding portion  310   b , and the portion  310   a  for regulating the position of the development cartridge  4  in the lengthwise direction are in alignment. 
   Therefore, it is possible to precisely position the positioning portion  310   h , the electrical contacts on the guide rib  310   b , and the portion  310   a  for regulating the position of the development cartridge  4  in terms of its lengthwise direction, relative to the image forming apparatus main assembly. In other words, the electrical contacts can be precisely positioned in the image forming apparatus, making it possible to reliably supply the development cartridge  4  with stable bias. 
   Also in the first and second embodiments, the positioning portion  310   c  having the cartridge positioning portion  310   h  shown  FIGS. 4 and 20  functions as the axle, about which the development cartridge  4  pivots. Further, when the development cartridge in the rotary device  40  is moved to the development position, the electrical contact point  311  ( 312 ) is not excessively pressed upon the electrical contact point  410  ( 411 ) fixed to the inward side of the image forming apparatus main assembly, and therefore, can be smoothly moved into the position in which the bias is supplied. Further, while the development cartridge  4  is moved into the development position, the pressure catching portion  310   k  of the guide rib  310   b  comes under the pressure generated by the resiliency of the spring  53  attached to the rotary device and the pressure generated by the rotational moment generated as the development roller  305  is rotationally driven, and the projection  310   m  is pressed upon the surface of the receptacle  400   e  shown in  FIG. 13 . As a result, the development cartridge  4  regains its development attitude, in which the electrical contact point  311  ( 312 ) on the guide rib  310   b  is positioned to supply the bias. 
   Further, the electrical contact point  311  ( 312 ) is disposed on the guide rib  310 , and the positioning projection  310   c , which is aligned with the electrical contact point  311  ( 312 ) virtually in the radial direction of the rotary device  40 , functions as the axle about which the positioning projection  310   c  pivots. Further, the pressure catching portion  310   k  of the guide rib  310   b  is under the pressure generated by the resiliency of the spring  53 , and the development cartridge  4  receives the rotational moment generated as the development roller  305  is rotationally driven. Therefore, it is assured that the electrical contact point  311  ( 312 ) remains accurately positioned even after the development cartridge  4  is moved to the development position. 
   Moreover, the cartridge  4  can be pivoted, making it possible to keep the electrical contact point  311  ( 312 ) apart from the electrical contact points  410  ( 411 ) of the image forming apparatus main assembly, or keep smaller the contact pressure between the electrical contact point  311  ( 312 ) and the electrical contact point  410  ( 411 ), until the last moment of the positioning of the development cartridge  4 . Therefore, it is possible to reduce the amount by which the electrical contact point  410  ( 411 ) of the image forming apparatus main assembly and the electrical contact point  311  ( 312 ) are shaved by each other due to the friction caused by the contact pressure. 
   Next, referring to  FIGS. 24–26 , the structural arrangement and method for attaching a bearing member  340 B and a side cover  310 B to the cartridge frame  300  will be described. 
     FIG. 24  shows one of the lengthwise ends of the cartridge frame  300 ;  FIG. 24  is a perspective view of one of the lengthwise ends of the cartridge frame  300 , immediately prior to the attachment of the bearing member  340 B to one of the lengthwise ends of the cartridge frame  300 , or immediately after the removal of the bearing member  340 B from the same lengthwise end of the cartridge frame  300 .  FIG. 25  is a perspective view of the same lengthwise end of the cartridge frame  300  as the one shown in  FIG. 24 , to which the bearing member  340 B has been attached, and to which the side cover  310 B is ready to be attached, or from which the side cover  310 B has just been removed.  FIG. 26  is a schematic drawing for showing how the bearing member  340 B and side cover  3101 B are attached to, or removed from, the cartridge frame  300 . 
   First, referring to  FIG. 24 , the method for attaching the bearing member  340 B to the cartridge frame  300  will be described. 
   The lengthwise end of the cartridge frame  300  shown in  FIG. 24  is provided with a groove  300   cc  and a projection  300   dd , which are on the top and bottom sides of the lengthwise end. The lengthwise end is also provided with screw holes  300   ee ,  300   ff , and  300   hh . Designated by reference numbers  305   c  and  304   a  are one end of the shaft of the development roller  305 , and one end of the shaft of the toner supply roller  304 , respectively. 
   The bearing member  340 B is provided with a bearing member cylinder  340   aa , which projects from the inward surface “a” of the bearing member  340 B, that is, the surface facing the cartridge frame  300 . It is also provided with a hole  340   bb . Further, it is provided with a hole  340 B 1  in which the aforementioned end  305   c  of the shaft of the development roller  305  is rotationally supported, and a hole  340 B 2  in which the aforementioned end  304   a  of the shaft of the toner supply roller  304  is rotationally supported. Further, it is provided with a first projection  340   dd  and a second projection  340   cc , which project from the outward surface b of the bearing member  340 B, that is, the surface opposite to the aforementioned surface “a”. The second projection  340   cc  supports a gear  307  (helical gear). As the development cartridge  4  is mounted into the image forming apparatus main assembly  100 , the gear  307  meshes with a gear (unshown) provided on the image forming apparatus main assembly  100  side, and receives the force for driving the development cartridge  4 . The first projection  340   dd  is provided with a screw hole  340   dd   1 , which is in the end portion of the first projection  340   dd.    
   Next, the side cover  310 B, which is attached to one of the lengthwise ends of the cartridge frame  300  will be described. 
   The side cover  310 B is provided with a projection  310   aa , which projects from the inward surface “a” of the side cover B, that is, the surface which faces the cartridge frame  300 . It also is provided with a cylinder  310   hh , which projects from the inward surface “a”. Further, it is provided with a first hole  310   dd , a second hole  310   cc , and a screw hole  310   ee.    
   Next, the method for attaching the bearing member  340 B to the cartridge frame  300  will be described. 
   First, the bearing member  340 B is aligned with the cartridge frame  300  so that as the bearing member  340 B is moved toward the cartridge frame  300 , the peripheral surface of the cylinder  340   aa  makes contact with the inward surface of the groove  300   cc , and the projection  300   dd  is put through the hole  340   bb . Incidentally, the external diameter of the cylinder  340   aa  is virtually the same as the internal diameter of the groove  340   aa . Thus, as the cylinder  340   aa  is fitted into the groove  300   cc , the position of the bearing member  340 B relative to the cartridge frame  300  becomes fixed. Further, the hole  340   bb  is long and narrow. Therefore, it prevents the bearing member  340 B from rotating about the cylinder  340   aa ; it is a so-called “rotation checker”. The end  305   c  of the development roller shaft is supported by the bearing member  340 B by being put through the hole  340 B 1 , and one end  304   a  of the toner supply roller shaft is supported by the bearing member  340 B by being put through the hole  340 B 2 . 
   Next, the bearing member  340 B is screwed to the cartridge frame  300  with screws  335  and  336 . The screw  335  is put through the screw hole  340   hh , and is screwed into the screw hole  300   hh . The screw  336  is put through the screw hole  340   ff , and is screwed into the screw hole  300   ff . As a result, the bearing member  340 B is attached to the cartridge frame  300 . 
   Next, referring to  FIG. 25 , the method for attaching the side cover  310 B to one of the lengthwise ends of the cartridge frame  300 , to which the bearing member  340 B has been attached, will be described. 
   First, the projection  310   aa  is to be placed in contact with the internal surface  340   aa   1  of the cylinder  340   aa  in the groove  300   cc , at the same time as the first projection  340   dd  is fitted into the first hole  310   dd . The first hole  310   dd  is a hole in the end portion of the cylinder  310   dd   1 , and the first projection  340   dd  is metallic and cylindrical. It fits into the cylinder  310   dd   1 , and at the same time, the second projection  340   cc  fits into the second hole  310   cc . The second projection  340   cc  is also metallic and cylindrical. The internal diameters of the hole  310   dd  and cylinder are virtually the same as the external diameter of the first projection  340   dd . The internal diameter of the hole  310   cc  is virtually the same as the external diameter of the projection  340   cc . However, the projection  310   aa  is loosely in contact with the internal surface of the cylinder  340   aa . Thus, the positional relationship of the side cover  310 B relative to the cartridge frame  300  is fixed by: the portion of the projection  340   dd , and the portion of the cylinder  310   dd   1 , which engage with each other; the portion of the projection  340   dd  and the portion of the hole  310   dd , which engage with each other; and the portion of the projection  340   cc , and the portion of the hole  310   cc , which engage with each other. Further, the contact between the projection  310   aa  and the internal surface  340   aa   1  of the cylinder  340   aa  prevents the side cover  310 B from rotating. Incidentally, because the side cover  310 B is formed of plastic, it is capable of deforming even if two adjacent portions of the side cover  310 B are used to position the side cover  310 B relative to the cartridge frame  300 . This deforming ability of the side cover  310 B is used to absorb the error in the distance between the hole  310   cc  and  310   dd , which occurs during manufacture. 
   Next, the side cover  310 B is attached to the cartridge frame  300  with screws  337  and  338 . The screw  337  is put through the hole  310   ee , and screwed into a screw hole  300   ee . The screw  338  is screwed into the screw hole  340   dd   1  in the end of the metallic projection  340   dd  integral with the bearing member  340 B. 
   Through the above described procedure, the side cover  340 B is attached to the cartridge frame  300 . The cylinder  310   hh  loosely fits in the projection  300   dd  put through the hole  340   bb.    
   Next, referring to  FIGS. 27–29 , the structural arrangement and method for attaching the bearing member  340 A and side cover  310 A to the other length end of the cartridge frame  300 , will be described. 
     FIG. 27  shows the other lengthwise end of the cartridge frame  300 ;  FIG. 27  is a perspective view of the other lengthwise end of the cartridge frame  300 , immediately prior to the attachment of the bearing member  340 A to the other lengthwise end of the cartridge frame  300 , or after the removal the bearing member  340 A from the same lengthwise end of the cartridge frame  300 .  FIG. 28  is a perspective view of the same lengthwise end of the cartridge frame  300  as the one shown in  FIG. 27 , to which the side cover  310 A is ready to be attached after the bearing member  340 A was attached, or from which the side cover  310 A has just been removed.  FIG. 29  is a schematic drawing for showing how the bearing member  340 A and side cover  310 A are attached to, or removed from, the cartridge frame  300 . 
   First, referring to  FIG. 27 , the method for attaching the bearing member  340 A to the cartridge frame  300  will be described. 
   The lengthwise end of the cartridge frame  300  shown in  FIG. 27  is provided with a groove  300   c  and a projection  300   d , which are on the top and bottom sides of the lengthwise end. This lengthwise end is also provided with screw holes  300   e ,  300   f ,  300   h , and  300   n . Designated by reference numbers  305   b  and  304   b  are the other end of the shaft of the development roller  305 , and the other end of the shaft of the toner supply roller  304 , respectively. 
   The bearing member  340 A is provided with a bearing member cylinder  340   a , which projects from the inward surface “a” of the bearing member  340 A, that is, the surface facing the cartridge frame  300 . It is also provided with a hole  340   b , screw holes  340   f  and  340   h , a hole  340 A 1  in which the other end  305   b  of the aforementioned development roller shaft is rotationally supported, and a hole  340 A 2  in which the other end  304   b  of the toner supply roller shaft is rotationally supported. Further, it is provided with a screw hole  340   h  in which the screw  334  is put through, and a screw hole  340   f  in which the screw  336  (not shown) is put through. 
   Next, the side cover  310 A, or the side cover which is attached to the other lengthwise end of the cartridge frame  300 , will be described. 
   The side cover  310 A is provided with an end cover projection  310   d   1 , which projects from the inward surface “a” of the side cover B, that is, the surface which faces the cartridge frame  300 . It also is provided with a cylinder  310   d   2 , which projects from the inward surface “a”. Further, it is provided with a screw holes  310   e ,  310   f , and  310   n.    
   Next, the method for attaching the bearing member  340 A to the cartridge frame  300  will be described. 
   Incidentally, the cartridge frame  300  is provided with a projection  300   d.    
   First, the bearing member  340 A is aligned with the cartridge frame  300  so that as the bearing member  340 A is moved toward the cartridge frame  300 , the peripheral surface of the cylinder  340   a  makes contact with the inward surface of the groove  300   c , and also so that the projection  300   d  is put through the hole  340   b . The external diameter of the cylinder  340   a  is virtually the same as the internal diameter of the groove  300   c . Thus, as the cylinder  340   a  is fitted into the groove  300   c , the position of the bearing  340 A relative to the cartridge frame  300  becomes fixed. Further, the hole  340   b  is long and narrow. Therefore, it prevents the bearing member  340 A from rotating about the cylinder  340   a ; it is a so-called “rotation checker”. The other end  305   b  of the development roller shaft is supported by the bearing member  340 A by being put through the hole  340 A 1 , and the other end  304   b  of the toner supply roller shaft is supported by the bearing member  340 A by being put through the hole  340 A 2 . 
   Next, the bearing member  340 A is attached to the cartridge frame  300  with screw  334 . The screw  334  is put through the screw hole  340   h , and is screwed into the screw hole  300   h . Through this procedure, the bearing member  340 A is attached to the cartridge frame  300 . 
   Next, referring to  FIG. 28 , the method for attaching the side cover  310 A to the other lengthwise end of the cartridge frame  300 , to which the bearing member  340 A has been attached, will be described. 
   First, the projection  310   a  is to be placed in contact with the internal surface  340   d   1  of the cylinder  340   a  in the groove  300   c , and at the same time, the projection  340   d  is placed in contact with the internal surface of the cylinder  310   d   2 . 
   The external diameter of the projection  310   d   1  is virtually the same as the internal diameter of the cylinder  340   a . Further, the internal hole of the cylinder  310   d   2  is long, and small in diameter, and the projection  300   d  loosely fits in the cylinder  310   d   2 . Thus, the positional relationship between the side cover  310 A relative to the cartridge frame  300  is fixed by the engagement between the projection  310   d   1  and the internal surface  340   a   1  of the cylinder  340   a , and the side cover  310 A is prevented from rotating by the engagement between the projection  300   d  and the internal surface  310   d   21  of the cylinder  310   d   2 . 
   Next, the side cover  310 A is attached to the cartridge frame  300  with screws  330 ,  331  and  333 . The screw  330  is put through the hole  310   e , and screwed into a screw hole  300   e . The screw  331  is screwed into the holes  310   f , and  340   f , and is screwed into the screw hole  300   f  of the cartridge frame  300 . The screw  333  is put through the hole  340   n , and is screwed into the screw hole  300   n  of the cartridge frame  300 . 
   Through the above described procedure, the side cover  340 A is attached to the cartridge frame  300 . 
   The above described embodiments can be summarized as follows. 
   First, the development cartridge  4  removably mountable in the main assembly of an electrophotographic image forming apparatus comprises: the cartridge frame  300 ; development roller  305  for developing an electrostatic latent image formed on the electrophotographic photoconductive drum  1 ; groove  300   cc  with which one of the lengthwise ends of the cartridge frame  300  is provided; projection  300   dd  with which the same lengthwise end of the cartridge frame  300  as that with the groove  300   cc  is provided; bearing member  340 B which rotationally supports one end  305   c  of the shaft of the development roller  305  disposed in parallel to the lengthwise direction of the cartridge frame  300 ; cylinder  340   aa  with which the bearing member  340 B is provided, and which makes contact with the inward surface of the groove  300   cc ; long and narrow hole  340   bb  with which the bearing member  340 B is provided, and through which the projection  300   dd  is put; metallic first projection  340   dd  provided on the outward surface of the bearing member  340 B, that is, the surface opposite to the inward surface “a” provided with the cylinder  340   aa ; metallic second projection  340   cc  which is provided on the outward surface “b”, and supports the gear to which the driving force is transmitted from the image forming apparatus main assembly when the development cartridge  4  is in the image forming apparatus main assembly  100 ; first screws  335  and  336  for holding the bearing member  340 B to the aforementioned lengthwise end of the cartridge frame  300 ; side cover  3101 B attached to the aforementioned lengthwise end of the cartridge frame  300  in a manner to cover the bearing member  340 B; first hole  310   dd  with which the side cover  3101 B is provided, and into which the aforementioned first projection  340   dd  is fitted; second hole  310   cc  with which the side cover  310 B is provided, and in which the aforementioned second projection  340   cc  is fitted; projection  310   aa  which is provided on the inward surface of the side cover  310 B, and is in the hole of the cylinder  340   aa , being in contact with the internal surface “a” of the cylinder  340   aa  in the groove  300   cc ; second screw  337  which holds the side cover  310 B to one of the lengthwise ends of the cartridge frame  300 ; and third screw  338  which holds the side cover  310 B to the first projection  340   dd  of the bearing member  340 B. 
   The development cartridge  4  has the coating roller  304  for coating the developer on the development roller  305 , and the bearing member  340 B is provided with the hole  340 B 2  through which one end  304   a  of the shaft of the coating roller  304  projects outward. 
   The development cartridge  4  has the end guide  310   b   1  which is for guiding the development cartridge  4  when mounting the development cartridge  4  into the image forming apparatus main assembly  100 , and which is on the outward surface “b”, that is, the surface opposite to the inward surface “a” on which the projection  310   aa  is provided. 
   The side cover  310 B of the development cartridge  4  has a hole  310   gg  into which one end of a cartridge locking portion  300   g  is retractably inserted to prevent the development cartridge  4  from dislodging from the image forming apparatus main assembly  100  after the mounting of the development cartridge  4  into the image forming apparatus main assembly  100 . 
   Further, the development cartridge  4  removably mountable in the main assembly of an electrophotographic image forming apparatus comprises: the cartridge frame  300 ; development roller  305  for developing an electrostatic latent image formed on the electrophotographic photoconductive drum  1 ; gear as a driving force receiving member  307  to which the driving force is transmitted from the image forming apparatus main assembly  100  when the development cartridge  4  is in the image forming apparatus main assembly  100 ; groove  300   c  with which the other lengthwise end of the cartridge frame  300  is provided; projection  300   d  with which the same lengthwise end of the cartridge frame  300  as that with the groove  300   c  is provided; bearing member  340 A which rotationally supports the other end  305   b  of the shaft of the development roller  305  disposed in parallel to the lengthwise direction of the cartridge frame  300 ; cylinder  340   a  with which the bearing member  340 A is provided, and which is placed in contact with the inward surface of the groove  300   c ; long and narrow hole  340   b  with which the bearing member  340 A is provided, and through which the projection  300   d  on the other side of the cartridge frame  300  is put; first screw  334  which holds the bearing member  340 A to the other lengthwise end of the cartridge frame  300 ; side cover  310 A attached to the aforementioned other lengthwise end of the cartridge frame  300  in a manner to cover the bearing member  340 A; projection  310   d   1  with which the side cover  310 A is provided, and is placed in contact with the internal surface of the cylinder  340   a  of the bearing member  340 A in contact with the inward surface of the groove  300   c ; cylinder  310   d   2  with which the side cover  310 A is provided, and the internal surface of which is placed in contact with the projection  300   d  put through the hole  340   b  of the bearing member  340 A; second screw  330  which holds the side cover  310 A to the other lengthwise end of the cartridge frame  300 ; and third screw  331  which holds both the bearing member  340 A and side cover  310 A to the other lengthwise end of the cartridge frame  300 . 
   The development cartridge  4  has the coating roller  304  for coating developer on the development roller, and the bearing member  340 A is provided with the hole  340 A 2  through which the other end  304   b  of the shaft of the coating roller  304  projects outward. The bearing member  340 A is also provided with a hole  340   r  through which a toner seal “t” is pulled out. The toner seal “t” keeps unsealably sealed the opening (unshown) with which the developer storage portion  303  is provided to release the developer in the developer storage portion  303 . 
   The side cover  310 A of the development cartridge  4  has the guide  310   b  which is for guiding the development cartridge  4  when mounting the development cartridge  4  into the image forming apparatus main assembly  100 , and which is on the outward surface “b” of the side cover  310 A, that is, the surface opposite to the inward surface “a” on which the projection  310   aa  is provided. It also has a hole  3101  through which the toner seal “t” for keeping unsealably sealed the opening of the developer holding storage portion  302  is pulled out. 
   Further, the side cover  310 A of the development cartridge  4  has a hole  310   g  into which one end of a cartridge locking member  300   g  is retractably inserted to prevent the development cartridge  4  from dislodging from the image forming apparatus main assembly  100  after the mounting of the development cartridge  4  into the image forming apparatus main assembly  100 . 
   The method for attaching the side cover  310 B to one end of the cartridge frame  300  comprises the following steps: 
   A shaft supporting step for rotationally supporting one end  305   c  of the shaft of the development roller  305 , with the bearing member  340 B 1 ; cylinder fitting step for fitting the cylinder  340   aa  of the bearing member  340 B into the groove  300   cc  located in one of the lengthwise ends of the cartridge frame  300 , in order to attach the bearing member  340 B to the cartridge frame  300 ; a projection placing step for putting the projection  300   dd  with which the same lengthwise end of the cartridge frame  300  as that having the groove  300   c  is provided, through the hole  340   bb  of the bearing member  340 B, in order to attach the bearing member  340   b  to the cartridge frame  300 ; a screwing step for putting the screws  335  and  336  through the holes  340   ff  and  340   hh , respectively, of the bearing member  340 B, and screwing the screws  335  and  336  into the screw holes  300   ff  and  300   hh , respectively, of the cartridge frame  300 , in order to attach the bearing member  340 B to the cartridge frame  300 ; a side cover projection placing step for placing the projection  310   aa  of the side cover  340 B in contact with the internal surface  340   aa   1  of the cylinder  340   aa , in the groove  300   cc  of the cartridge frame  300 , of the bearing member  340 B; a first fitting step for fitting the metallic first projection  340   dd  of the bearing member  340 B into the first hole  310   dd  of the side cover  310 B; a second fitting step for fitting the metallic second projection  340   cc  of the bearing member  340 B into the second hole  310   cc  of the side cover  310 B; a first screwing step for putting the screw  337  through the hole  310   ee  of the side cover  310 B, and screwing the screw  337  into the screw hole  300   ee  of the cartridge frame  300 , in order to attach the side cover  3101 B to the cartridge frame  300  with the use of the screw  337 ; a second screwing step for putting the screw  338  through the hole  310   dd  of the side cover  3101 B, and screwing the screw  338  into the screw hole  340   dd   1  of the first projection  340   dd  of the bearing member  340 B, in order to attach the side cover  3101 B to the cartridge frame  300  with the use of the screw  338 . 
   The method for attaching the side cover  310 B also comprises: the shaft placing step for projecting outward the other end  304   a  of the shaft of the coating roller  304  for coating developer on the development roller  305 , through the hole  340 B 2  of the bearing member  340 B when attaching the bearing  340 B to the cartridge frame  300 . 
   Further, the method for attaching the side cover  310 B comprises: the locking step for making one end of the cartridge locking portion  300   g  for preventing the development cartridge  4  from dislodging from the image forming apparatus main assembly  100 , project outward through the locking hole  310   gg  of the side cover  310 B when mounting the development cartridge  4  into the image forming apparatus main assembly  100 . 
   In comparison, the method for attaching the side cover  310 A, or the other side cover, to the other lengthwise end of the cartridge frame  300  comprises the following steps: 
   A shaft supporting step for rotationally supporting the other end  305   b  of the shaft of the development roller  305 , in terms of the lengthwise direction of the development roller  305 , by the bearing member  340 A, or the other bearing member; cylinder placing step for placing the cylinder  340   a  of the bearing member  340 A, in the groove  300   c  located in the other lengthwise end of the cartridge frame  300 , in order to attach the bearing member  340 A to the other lengthwise end of the cartridge frame  300 ; a projection placing step for putting the projection  300   d  of the other lengthwise end of the cartridge frame  300  through the hole  340   b  of the bearing member  340 A, in order to attach the bearing member  340 A to the cartridge frame  300 ; a screwing step for putting the screw  334  through the hole  340   b  of the bearing member  340 A, and screwing the screw  334  into the screw hole  300   h  of the cartridge frame  300 , in order to attach the bearing member  340 A to the cartridge frame  300  with the use of screw  334 ; a projection placing step for placing the projection  310   d   1  of the side cover  310 A in contact with the internal surface  340   a   1  of the cylinder  340   a , in the groove  300   c  of the other lengthwise end of the cartridge frame  300 , of the bearing member  310 A; a cylinder fitting step for fitting the cylinder  310   d   2  of the side cover  310 A around the projection  300   d  of the other lengthwise end of the cartridge frame  300 , which has been put through the hole  340   b  of the bearing member  340 A; a first screwing step for putting the screw  333  through the hole  310   n  of the side cover  310 A, and screwing into the screw hole  300   n  of the cartridge frame  300 , in order to attach the side cover  310 A to the cartridge frame  300  with the use of the screw  333 ; and a second screwing step for putting the screw  331  through the holes  310   f  and  340   f  of the side cover  310 A and bearing member  340 A, respectively, and screwing the  331  into the screw hole  300   f  of the cartridge frame  300 , in order to screw the side cover  310 A to the cartridge frame  300  with the use of the screw  331 . 
   The method for attaching the side cover  310 A to the other lengthwise end of the cartridge frame  300  also comprises the shaft placing step for inserting the other end  304   b  of the shaft of the coating roller  304  for coating developer on the development roller  305 , through the hole  340   m  of the bearing member  340 A, from the inward side of the hole  340   m , so that the other end  304   b  sticks out from the outward side of the hole  340   m , when attaching the bearing member  340 A to the cartridge frame  300 . 
   It also comprises: the locking step for making the other end of the cartridge locking portion  300   g  for preventing the development cartridge  4  from dislodging from the image forming apparatus main assembly  100 , project outward through the locking hole  310   g  of the side cover  310 A after the placement of the development cartridge  4  in the image forming apparatus main assembly  100 ; and the toner seal placing step for placing the toner seal “t” for keeping unsealably sealed the developer releasing opening (unshown) of the developer storage portion  302 , which is holding developer, through the toner seal hole  3101 , from the inward side of the toner seal hole  3101 , so that the toner seal “t” sticks out from the outward side of the toner seal hole  3101 . 
   Incidentally, the above described cartridge frame  300 , bearing members  340 A and  340 B, and side covers  310 A and  310 B are made of plastic (for example, styrene). In comparison, the first and second projections  340   cc  and  340   dd  are made of metallic material. 
   The structure of a development cartridge does not need to be limited to those in the above described embodiments, that is, the structure in which the developing member, and the developer storage portion in which the developer used by the developing member for developing an electrostatic latent image, are integrated into a unit which can be removably mountable in the main assembly of an image forming apparatus. For example, a development cartridge does not need to have a developer storage portion. Further, a development cartridge may integrally comprise other components, members, etc., than a developing member and a developer storage portion, in addition to the developing member and developer storage. A process cartridge means a cartridge in which an electrophotographic photoconductive member and a developing member are integrally disposed, and which can be removably mountable in the main assembly of an image forming apparatus. 
   According to the above described embodiments of the present invention, before attaching the side covers  310 A and  310 B to the cartridge frame  300 , the bearing members  340 A and  340 B are attached to the cartridge frame  300 , as described above, fixing thereby the positions of the development roller  305  and coating roller  304  relative to the cartridge frame  300 . Also according to the above described embodiments, the bearing members  340 A and  340 B are screwed to the cartridge frame  300 , making it possible to attach the bearing members  340 A and  340 B to the cartridge frame  300  before attaching the side covers  310 A and  310 B to the cartridge frame  300 . In other words, before the side covers  310 A and  310 B are attached to the cartridge frame  300 , the bearing members  340 A and  340 B will have been fixed to the cartridge frame  300 , making it easier to attach the side covers  310 A and  310 B to the cartridge frame  300 . 
   Also according to the above described embodiments, the projection  310   d   1  perfectly fits into the hollow  340   a   1  of the hollow cylinder  340   a , accurately positioning the bearing member  340 A and side cover  310 A relative to the cartridge frame  300 . In other words, both the bearing member  340 A and side cover  310 A are positioned by the same projection, or the projection  310   d    1 , increasing thereby the degree of accuracy with which the bearing member  340 A and side cover  310 A are positioned relative to the cartridge frame  300 . Therefore, the degree of accuracy with which the side cover  310 A is attached to the cartridge frame  300  is improved. 
   Also according to the above described embodiments, the bearing members  340 A and  340 B are screwed to the cartridge frame  300 , increasing thereby the degree of solidity with which the bearing members are attached to the cartridge frame  300 . In addition, the side covers  310 A and  310 B are directly screwed to the cartridge frame  300 , increasing thereby the degree of solidness with which the side covers  310 A and  310 B are attached to the cartridge frame  300 . Further, both the bearing member  340 A and side cover  310 A are screwed to the cartridge frame  300  with a single screw, that is, the same screw. This also adds to the solidity with which the side covers  310 A is attached to the cartridge frame  300 . 
   Also according to the above described embodiments, the first projection  340   dd  and second projection  340   cc  are made of metallic material (for example, stainless steel). Moreover, the metallic projection  340   dd  is fitted in the hollow of the hollow cylinder  310   dd , and the external surface of this hollow cylinder  310   dd  is placed in contact with the image forming apparatus main assembly  100 . 
   Thus, as the side cover  310 B is attached to the cartridge frame  300 , the metallic projection  340   dd  doubles as a member for reinforcing the side cover  310 B. Therefore, even though the position of the development cartridge  4  relative to the image forming apparatus main assembly  100  is fixed by a part of the side cover  310 B, the side cover  310 B is prevented from deforming, or the deformation of the side cover  310 B is minimized. Therefore, the development cartridge  4  is positioned relative to the image forming apparatus main assembly  100  at a higher degree of accuracy. 
   Further, if an assembly line worker forgets to attach the bearing member  340 A to the cartridge frame  300  during the assembly of a development cartridge  4 , it becomes impossible to accurately position the side cover  310 A relative to the cartridge frame  300 . As a result, it is obvious to the assembler that the assembler or someone else forgot to attach the bearing member  340 A. This is because the position of the projection  310   d   1  must be fixed by the internal surface of the hollow cylinder  340   a.    
   Also according to the above described embodiments, the position of the adjacencies of the positioning portion  310   dd   1  of the side cover  310 B, for positioning the side cover  310 B relative to the image forming apparatus main assembly  100 , is fixed by the metallic shaft  340   dd , and the side cover  310 B is screwed to the cartridge frame  300 . Further, the metallic shaft  340   cc  is adjacent the metallic shaft  340   dd . Therefore, it is difficult for the side cover  310 B to deform, increasing thereby the strength (rigidity) of the positioning portion  310   dd   1 . 
   Further, with the provision of the above described projections, the development roller  305  and coating roller  304  can be accurately positioned by the bearing members  340 A and  340 B alone. Thus, when attaching the side covers  310 A and  310 B after the attachment of the bearing members  340 A and  340 B, the bearing members  340 A and  340 B, and both rollers  304  and  305 , will have been accurately positioned, making it easier to attach the side covers  310 A and  310 B. Therefore, it is easier to assembly a development cartridge  4 . 
   The present invention made it possible to improve the efficiency with which the side cover was attached to the cartridge frame. 
   The present invention made it possible to improve the accuracy with which the side cover was positioned relative to the cartridge frame when attaching the side cover to the cartridge frame. 
   The present invention made it possible to increase the degree of solidity with which the side cover was attached to the cartridge frame. 
   Further, the present invention made it possible to make the metallic projection of the bearing member double as a member for reinforcing the side cover as the side cover was attached to the cartridge frame, preventing the side cover from deforming, or minimizing the deformation of the side cover, even though the position of the development cartridge relative to an electrophotographic image forming apparatus main assembly was fixed by a part of the side cover, when the development cartridge was in the main assembly of the image forming apparatus. Therefore, it was possible to increase the accuracy with which the development cartridge was positioned relative to the main assembly of the image forming 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.