Patent Publication Number: US-6343192-B1

Title: Developing device frame, process cartridge, and electrophotographic image forming apparatus

Description:
This is a continuation application of application Ser. No. 08/906,094, filed Aug. 5, 1997, now U.S. Pat. No. 6,169,865, which is a continuation of application Ser. No. 08/687,952, filed Jul. 26, 1996, now abandoned. 
    
    
     FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to a developing device frame, a process cartridge and an electrophotographic image forming apparatus usable with the process cartridge. 
     Here, the electrophotographic image forming apparatus means an apparatus which forms images on recording medium, using an electrophotographic image forming process. It includes an electrophotographic copying machine, an electrophotographic printer (for example, LED printer, laser beam printer), an electrophotographic facsimile machine, an electrophotographic word processor, and the like. 
     The process cartridge means a cartridge having as a unit an electrophotographic photosensitive member, and charging means, developing means and cleaning means, which is detachably mountable to a main assembly of an image forming apparatus. It may include as a unit an electrophotographic photosensitive member and at least one of charging means, developing means and cleaning means. It may include as a unit developing means and an electrophotographic photosensitive member. 
     An image forming apparatus using electrophotographic process is known which is used with the process cartridge. This is advantageous in that the maintenance operation can be, in effect, carried out by the users thereof without expert service persons, and therefore, the operativity can be remarkably improved. Therefore, this type is now widely used. 
     The process cartridge is constituted by a cleaning unit having integral charging means, cleaning means and photosensitive drum, and a developing unit having integral developing means and toner container for supplying toner to the developing means. The process cartridge is provided by coupling the cleaning unit and the developing unit with a-coupling member. 
     Here, the developing unit comprises a toner frame for accommodating the toner to be supplied to the developing means, and a developing device frame for supporting the developing means. The toner frame and the developing device frame are unified by ultrasonic welding or the like. 
     To the developing frame, developing roller and developing blade for charging the toner on the developing roller, which are extended in the longitudinal direction, are mounted. 
     It is desired to mount the parts to the developing device frame efficiently. 
     Thus, the present invention was made to further develop the aforementioned art. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a principal object of the present invention to provide a developing frame process cartridge and an electrophotographic image forming apparatus wherein parts are efficiently mounted to a developing frame. 
     It is another object of the present invention to provide a developing frame, process cartridge and an electrophotographic image forming apparatus, which are easy to assemble. 
     It is a further object of the present invention to provide a developing device frame, process cartridge and electrophotographic image forming apparatus, wherein an antenna member is mountable to produce an electric signal to be transmitted to detecting means provided in the main assembly of the electrophotographic image forming apparatus in order to notify the mounting of the process cartridge to the main assembly of the electrophotographic image forming apparatus. 
     It is a further object of the present invention to provide a developing device frame, process cartridge and an electrophotographic image forming apparatus, which has a gear mounting portion for mounting a gear for transmitting, to the stirring member, driving force for rotating a stirring member, wherein the gear mounting portion is mounted in the same side where an extension discharging portion of the antenna member mounted to the antenna member mounting portion is located, in the longitudinal direction of the developing device frame. 
     These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side sectional view of an electrophotographic image forming apparatus according to a first embodiment of the present invention. 
     FIG. 2 show an outer appearance of the apparatus of FIG.  1 . 
     FIG. 3 is a side sectional view of a process cartridge according to an embodiment of the present invention. 
     FIG. 4 shows a schematic outer appearance of the process cartridge of FIG.  3 . 
     FIG. 5 is a right side view of the process cartridge of FIG.  3 . 
     FIG. 6 is a left side view of the process cartridge of FIG.  3 . 
     FIG. 7 shows an outer appearance of the process cartridge of FIG.  3 . 
     FIG. 8 shows an outer appearance of the process cartridge of FIG. 3, as seen from the bottom. 
     FIG. 9A shows an outer appearance of a cleaning unit of the process cartridge of FIG.  3 . 
     FIG. 9B shows an outer appearance of a developing unit of the process cartridge of FIG.  3 . 
     FIG. 10 is a side view illustrating mounting and demounting operation of the process cartridge of FIG. 3 relative to the main assembly of the image forming apparatus. 
     FIG. 11 is a side view illustrating mounting and demounting operation of the process cartridge of FIG. 3 relative to the main assembly of the image forming apparatus. 
     FIG. 12 is a side view illustrating mounting and demounting operation of the process cartridge of FIG. 3 relative to the main assembly of the image forming apparatus. 
     FIG. 13 is a side view illustrating mounting and demounting operation of the process cartridge of FIG. 3 relative to the main assembly of the image forming apparatus. 
     FIG. 14 is a side view illustrating mounting and demounting operation of the process cartridge of FIG. 3 relative to the main assembly of the image forming apparatus. 
     FIG. 15 is a side view illustrating mounting and demounting operation of the process cartridge of FIG. 3 relative to the main assembly of the image forming apparatus. 
     FIG. 16 is a side view illustrating mounting and demounting operation of the process cartridge of FIG. 3 relative to the main assembly of the image forming apparatus. 
     FIG. 17 is a side view illustrating mounting and demounting operation of the process cartridge of FIG. 3 relative to the main assembly of the image forming apparatus. 
     FIG. 18 is a perspective view of an inside of the main assembly of the apparatus. 
     FIG. 19A is a perspective view of an inside of the main assembly of the apparatus. 
     FIG. 19B is a side view of an inside of the main assembly of the apparatus. 
     FIG. 20 shows contact between a contact member and a contact point. 
     FIGS. 21A,  21 B, and  21 C show contact between a contact member and a contact point. 
     FIG. 22 is a side view of a process cartridge according to an embodiment of the present invention. 
     FIG. 23A shows an outer appearance of a developing holder. 
     FIG. 23B is a perspective view of an inside of a developing device holder. 
     FIG. 24 is a sectional view taken along a line I—I in FIG.  23 B. 
     FIG. 25 is an enlarged view of a toner detection point in FIG.  23 B. 
     FIG. 26 is an exploded perspective view of a developing unit. 
     FIG. 27 is a perspective view of a developing device frame or developing frame. 
     FIG. 28 is a perspective view of a developing unit without the developing holder. 
     FIG. 29 is a perspective view of a toner frame. 
     FIG. 30 is a perspective view of the toner frame after a toner seal is mounted. 
     FIGS. 31A and 31B are longitudinal sectional views of the toner seal of FIG.  30 . 
     FIG. 32 is a sectional view taken along a line RO—RO of FIG.  3 . 
     FIG. 33 is an exploded perspective view of a toner frame. 
     FIG. 34 is a bottom view of a process cartridge. 
     FIG. 35 is a side view illustrating a gear train of FIG.  28 . 
     FIG. 36 is a side view of a toner frame. 
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION 
     Hereinafter, the preferable embodiments of the present invention will be described. In the following descriptions, the widthwise direction of a process cartridge B means the direction in which the process cartridge B is inserted or removed from the main assembly  14  of an image forming apparatus (hereinafter, apparatus main assembly). This direction coincides with the direction in which the recording medium is conveyed. The longitudinal direction of the process cartridge B means the direction perpendicular (substantially) to the direction in which the process cartridge B is inserted or removed from the apparatus main assembly  14 . This direction intersects with (is substantially perpendicular to) the direction in which the recording medium is conveyed. FIG. 1 is a schematic view of an embodiment of the electrophotographic image forming apparatus (laser beam printer) in accordance with the present invention, and FIG. 2 is an external perspective view thereof. FIGS. 3-8 are drawings depicting an embodiment of the process cartridge in accordance with the present invention. FIG. 3 is a sectional side view of the process cartridge; FIG. 4, an external perspective view thereof; FIG. 5, a right side view thereof; FIG. 6, a left side view thereof; FIG. 7, a perspective view as seen from above; and FIG. 8 is a perspective view as seen from below. Also in the following description, the top surface of the process cartridge B means the surface which faces upward when the process cartridge B is in the apparatus main assembly  14 , and the bottom surface means the surface which faces downward when the process cartridge B is in the main assembly  14 . 
     [Electrophotographic Image Forming Apparatus A and Process Cartridge B] 
     To begin with, referring to FIGS. 1 and 2, a laser beam printer as an electrophotographic image forming apparatus, to which the embodiment of the present invention has been applied, will be described. FIG. 3 is a side view of a process cartridge B. 
     Referring to FIG. 1, this laser beam printer A is of a type which forms an image on recording medium, for example, recording paper, OHP sheet, or fabric, through the electrophotographic image forming process. First, a toner image is formed on a drum-shaped electrophotographically sensitive member (hereinafter, photosensitive drum) as an image bearing member. More specifically, the photosensitive drum is charged by charging means, and then, a laser beam is projected onto the charged photosensitive member from optical means in response to imaging data, to form a latent image on the photosensitive member in response to the imaging data. Next, this latent image is developed into a toner image by developing means. Meanwhile, a sheet of recording medium  2  placed in a cassette  3   a  is conveyed, being thereby fed out, by a conveying means  3  comprising a pair of pickup rollers  3   b  and  3   c,  and a pair of registration rollers  3   d  and  3   e,  and the like, in synchronism with the toner image formation. Next, a voltage is applied to a transfer roller  4  as transferring means, whereby the toner image formed on the photosensitive drum, which a process cartridge B comprises, is transferred onto the recording medium  2 . Then, the recording medium having received the toner image is delivered to a fixing means  5 . This fixing means  5  comprises a driving roller  5   c  and a fixing roller  5   b  containing a heater  5   a,  and applies heat and pressure to the recording medium  2 , which is passed through the fixing means  5 , whereby the transferred toner image is fixed. Next, the recording medium  2  now be ring the fixed toner image conveyed and discharged into a discharge tray  6 , through a sheet-reversing path  3   j,  by a group of discharging roller pairs  3   g,    3   h  and  3   i.  This discharge tray  6  is provided on the top surface of the apparatus main assembly  14  of the image forming apparatus A. The apparatus A comprises also a pivotable flapper  3   k  and a discharge roller pair  3   m,  and when this flapper  3   k  is operated, the recording medium  2  can be discharged without being flipped over through the discharge roller pair  3   m,  without going through the sheet-reversing path  3   j.  In this embodiment, the aforementioned pickup roller  3   b,  conveyer roller pairs  3   c  and  3   d,  register roller  3   e,  conveyer guide  3   f,  discharge roller pairs  3   g,    3   h  and  3   i,  and discharge roller pair  3   m  constitute conveying means. 
     Referring to FIGS. 3-8, in the process cartridge B, the surface of a photosensitive drum  7  as the image bearing member with a photosensitive layer  7   e  (FIG. 20) is uniformly charged by applying a voltage to a charging roller  8 , which is a charging means, while the photosensitive drum  7  is rotated. Next, a laser beam carrying the image data is projected by an optical system  1  onto the photosensitive drum  7  through an exposure opening  9 , whereby a latent image is formed on the photosensitive drum  7 . This latent image is developed with toner by a developing means  9 . 
     The charging roller  8  is placed in contact with the photosensitive drum  7  to charge the photosensitive drum  7 , wherein this charging roller  8  is rotated by the rotation on the photosensitive drum  7 . The developing means  9  develops the latent image formed on the photosensitive drum  7 , by supplying the toner to the photosensitive drum  7 , on the regions to be developed. The optical system  1  comprises a laser diode  1   a,  a polygon mirror  1   b,  a lens  1   c,  and a full reflection mirror  1   d.    
     As the toner stirring member  9   b  of the aforementioned developing means  9  is rotated, the developing means  9  stirs the toner within the toner container  11 A, and sends it toward the developing roller  9   c,  and as a developing roller  9   c,  in which a magnet is fixed, is rotated, a layer of toner triboelectrically charged by a developing blade  9   d  is formed on the surface of the developing roller  9   c.  The toner is supplied from this toner layer to the photosensitive drum  7 , on the region to be developed. As the toner is transferred onto the photosensitive drum  7  in correspondence with the latent image, the latent image is visualized. This developing blade  9   d  regulates the amount of the toner coated on the peripheral surface of the developing roller  9   c.  Also, stirring members  9   e  and  9   f  for stirring and circulating the toner are rotatively mounted adjacent to the developing roller  9   c.    
     Next, a voltage with a polarity opposite to that of the toner image is applied to the transfer roller  4 , whereby the toner image on the photosensitive drum  7  is transferred onto the recording medium  2 . Then, the residual toner on the photosensitive drum  7  is removed by a cleaning means  10 . The cleaning means  10  comprises an elastic cleaning blade  10   a,  which is disposed in contact with the photosensitive drum  7 . The toner remaining on the photosensitive drum  7  is scraped off by the elastic cleaning blade  10   a  to be collected in a waste toner collector  10   b.    
     The process cartridge B is formed by combining: a toner chamber portion  11  of the cartridge frame (hereinafter toner chamber frame), which constitutes a portion of the toner container  11 A (toner containing portion) for storing the toner; a developing chamber portion  12  of the frame (hereinafter, developing chamber frame), which contains the developing means such as the developing roller  9   c;  and a cleaning means portion  13  of the frame (hereinafter, cleaning means frame), which comprises the photosensitive drum  7 , cleaning means such as the cleaning blade  10   a,  charging roller  8 , and the like. This process cartridge B is removably installed in the apparatus main assembly  14  by an operator. 
     The process cartridge B is provided with an exposure opening  1   e,  which allows the light beam carrying the image data to be irradiated onto the photosensitive drum  7 , and a transfer opening  13   n,  which allows the photosensitive drum  7  to face directly the recording medium  2 . More specifically, the exposure opening  1   e  is provided in the cleaning means portion  13 , and the transfer opening  13   n  is formed between the developing chamber portion  12  and cleaning means portion  13 . 
     Next, the structure of the housing of an embodiment of the process cartridge B according to the present invention will be described. 
     This process cartridge B in accordance with the present invention is assembled in the following manner. First, the toner chamber frame  11  and developing chamber frame  12  are joined. Then, the cleaning means frame  13  is rotatively attached to the structure formed by joining the preceding two frame portions, completing thereby a cartridge housing. Next, the aforementioned photosensitive drum  7 , charging roller  8 , developing means  9 , cleaning means  10  and the like are disposed within the housing to complete the process cartridge B. The process cartridge B is removably installed in a cartridge installing means provided within the apparatus main assembly  14 . 
     [Structure of Housing of Process Cartridge B] 
     The housing of the process cartridge B according to the present invention is constructed by joining the toner chamber frame  11 , developing chamber frame  12 , and cleaning means frame  13 , and its structure will be described below. 
     Referring to FIGS. 3,  9 A, and  9 B, the toner chamber frame  11  comprises a toner storing container portion  11 A, in which the toner stirring member  9   b  for stirring and sending out the contained toner is mounted. The developing roller  9   c  and developing blade  9   d  are mounted on the developing chamber frame  12 , and the stirring members  9   e  and  9   f,  which circulate the toner within the developing chamber, are rotatively mounted adjacent to the developing roller  9   c.  Further, an antenna rod  9   h  is disposed adjacent to the developing roller  9   c,  substantially in parallel thereto. The aforementioned toner chamber frame  11  and developing chamber frame  12  are melt-welded (by the ultrasonic welding in this embodiment) to form a developing unit D as an integral second frame member (refer to FIG.  9 B). 
     The photosensitive drum  7 , charging roller  8 , and cleaning means  10  are mounted on the cleaning means frame  13 . Further, a drum shutter member  18 , which covers and protects the photosensitive drum  7  when the process cartridge B is out of the apparatus main assembly  14 , is attached to the cleaning means portion  13  of the frame to form a cleaning unit C as the first frame member (refer to FIG.  9 A). 
     Then, the developing unit D and cleaning unit C are joined with a joining member  22 , in such a manner as to be pivotable relative to each other, to complete the process cartridge B. More specifically, referring to FIGS. 9A, and  9 B, an axis  20  is provided at the end of an arm portion  19  formed at each of the longitudinal ends (in the axial direction of the developing roller  2   c ) of the developing chamber portion  12  of the frame (refer to FIG.  9 B). On the other hand, a recessed portion  21 , in which the axis  20  is fitted to fix the positional relationship between the developing D and cleaning unit C, is provided at each of the longitudinal ends of the cleaning means portion  13  of the frame (refer to FIG.  9 A). The joining member  22  is mounted on the cleaning means portion  13  of the frame by inserting the axis  20  into the recessed portion  21 , whereby the developing and cleaning units D and C are joined in a manner so as to pivot relative to each other about the axis  20 . The joining member  22  is provided with a compression spring  22   a,  so that the developing chamber frame  12  is pressed downward to reliably press the developing roller  9  toward the photosensitive drum  7 . Further, a spacer ring  9   i  having a larger diameter than the developing roller  9  is provided at each of the longitudinal end portions of the developing roller  9 , wherein this ring  9   i  is pressed on the photosensitive drum  7  to keep a predetermined distance (approximately 300 μm) between the photosensitive drum  7  and developing roller  9   c.  Thus, the positional relationship between the peripheral surface of the photosensitive drum  7  and the peripheral surface of the developing roller  9   c  can be precisely maintained by the elastic force of the compression spring  22   a.    
     [Structure of Guiding Means of Process Cartridge B] 
     Next, guiding means, which guides the cartridge B when the cartridge B is installed into the apparatus main assembly  14  or removed therefrom, will be described referring to FIGS. 4-9B, wherein FIG. 5 is a right-hand side view of the cartridge B relative to the direction of an arrow mark X, in which the cartridge B is inserted into the apparatus main assembly  14  (right-hand side as seen from the developing unit D side), and FIG. 6 is a left-hand side view of the same. 
     As is evident from the drawings, the guiding means, which serves as a guide when the process cartridge B is inserted into the apparatus main assembly  14  or removed therefrom, is provided on each of the longitudinal end surfaces of the housing  100 . This guiding means comprises a cylindrical guide  13   a  as a first guiding member, a long guide  12   a  as a second guiding member, and a short guide  13   b  as a third guiding member. 
     The cylindrical guide  13   a,  that is, a cylindrical member, projects outward from the lateral surface of the cleaning means frame  13 , in line with the axis of the photosensitive drum  7 . It supports the drum shaft  7   a,  which supports the photosensitive drum  7 , in such a manner as not to rotate it. The long guide  12   a  is provided on each of the longitudinal end surfaces of the developing chamber frame  12 , and bridges the surfaces of the developing chamber frame  12  and cleaning means frame  13 . The short guide  13   b  is provided on each of the longitudinal end surfaces of the cleaning means frame  13 , above the cylindrical guide  13   a.  More specifically, the long guide  12   a  is integrally formed on developing roller holders  40  and  41  (refer to FIG.  23 ), which will be described later. Further, the cylindrical guide  13   a  and short guide  13   b  are integrally formed on the cleaning means frame  13 . 
     The long guide  12   a  extends in the direction (arrow X direction), in which the cartridge B is inserted, and its angle is set to be substantially equal to an angle at which the process cartridge B is inserted. The cylindrical guide  13   a  is disposed so as to fall in the path of the imaginary extension of the long guide  12   a  in the cartridge inserting direction, and the short guide  13   b  is substantially parallel to the long guide  13   a.  Referring to FIG. 6, the cylindrical guide  13   a,  second guide member  12   a,  third guide member  13   b  are also provided on the longitudinal side surface opposite to the one illustrated in FIG. 10, and their configuration and positions are the same as those shown in FIG.  5 . These three guiding members project substantially the same distance from the external surface of the cleaning means frame  13  and developing chamber frame  12 , which are in the same plane. 
     Hereinafter, more detailed description will be given. 
     The cylindrical guide  13  as the first guiding member is provided on each of the lateral surfaces C 1  (right-hand side- 13   c ) and C 2  (left-hand side  13   d ) of the cleaning unit C, wherein the side C 1  is the right-hand side portion  13   c  of the cleaning means frame  13 , relative to the axial direction of the photosensitive drum  7 , as the cartridge B is seen from the developing unit D side (as the cartridge B is seen from the downstream side of the cartridge B inserting direction). The other side C 2  is the left-hand side portion of the cleaning means frame  13 , relative to the axial direction of the photosensitive drum  7 . This cylindrical guide  13   a  is a cylindrical member, which projects from each of both longitudinal end surfaces  13   c  and  13   d  of the cleaning means frame  13  in the axial direction of the photosensitive drum  7 . The drum shaft  7   a  is supported by this cylindrical member  13   a,  which fits around the drum shaft  7   a.  In other words, the drum shaft  7   a  is guided by the guiding member  16   a,  which will be described later, with the cylindrical member  13   a  being interposed, and then, the position of the drum shaft  7   a  is fixed by a groove  16   a   5  (refer to FIGS.  10 - 17 ). 
     The long guide  12   a  as the second guide member is provided on each of the longitudinal end surfaces D 1  (right-hand portion  12   c ) and D 2  (left-hand side  12   d ) of the developing unit D, wherein one surface, D 1 , of the lateral portion is the right-hand portion  12   c,  relative to the axial direction of the photosensitive drum  7 , of the developing chamber frame portion  12 , and the other surface, D 2 , is the left-hand side portion  12   d,  relative to the axial direction of the photosensitive drum  7 , of the developing chamber frame portion  12 . The long guide  12   a  is disposed away from the cylindrical guide  13   a,  being on the upstream side of the cylindrical guide  13   a,  relative to the cartridge inserting direction (arrow X direction). More precisely, the long guide  12   a  is disposed within a region L formed between the top and bottom imaginary lines  111  and  112  (FIG. 5) extended parallel in the inserting direction and tangentially from the peripheral surface of the cylindrical guide  13   a,  and this long guide  12   a  bridges between the developing chamber frame portion  12  and cleaning means frame portion  13 , with its inserting end portion  12   a   1  extending over the lateral surface area of the cleaning frame portion  13  (by an approximate distance of 1 mm to 3 mm). 
     The short guide  13   b  as the third guiding member is provided on the lateral surfaces  13   c  and  13   d  of the cleaning unit C, above the cylindrical guide  13   a.  More specifically, the short guide  13   b  is substantially directly above the cylindrical guide  13   a  as seen from the cartridge inserting direction. In other words, the short guide  13   b  is disposed within the region  15  formed between two parallel lines  113  and  114 , which are drawn in such a manner as to be tangent to the peripheral surface of the cylindrical guide  13   a  and substantially perpendicular to the cartridge inserting direction (arrow X direction). In addition, the short guide  13   b  is substantially parallel to the long guide  13   a.    
     Here, typical measurements of the guiding members will be listed. Hereinafter, a tolerable range means the measurement range adopted in this embodiment of the process cartridge. 
     The cylindrical guide  13   a  is approximately 10.0 mm in diameter (tolerable range of 7.5 mm to 10.0 mm); the long guide  12   a,  approximately 36.0 mm in length (tolerable range of 15.0 mm to 41.0 mm) and approximately 8.0 mm in width (tolerable range of 1.5 mm to 10.0 mm); and short guide  13   b  is approximately 10.0 mm in length (tolerable range of 3.0 mm to 17.0 mm) and approximately 4.0 mm (tolerable range of 1.5 mm to 7.0 mm) in width. Further, the distance between the peripheral surface of the cylindrical guide  13   a  and the inserting end portion  12   a   1  of the long guide  12   a  is approximately 9.0 mm. 
     The distance between the peripheral surface of the cylindrical guide  13   a  and the bottom end tip  13   b   1  of the short guide  13   b  is approximately 7.5 mm (tolerable range of 5.5 mm to 9.5 mm). 
     Next, a regulatory contact portion  13   e  and a disengagement contact portion  13   f,  which are provided on the top surface  13   d  of the cleaning unit C, will be described. Here, the top surface means such a portion of the leaning unit C surface that is going to face upward when the process cartridge B is installed into the apparatus main assembly  14 . In this embodiment, it is the top surface  13   i  of the cleaning unit C. 
     The regulatory contact portion  13   e  and disengagement contact portion  13   f  are provided on each of the right lateral end portion  13   c  and left lateral end portion  13   d  of this surface  13   i.  This regulatory contact  13   e  fixes the position of the process cartridge B in the apparatus main assembly  14 . More specifically, when the process cartridge B is inserted into the apparatus main assembly  14 , the contact  13   e  comes in contact with a fixing member  25  provided on the apparatus main assembly  14  (FIGS.  10 - 17 ), whereby the position of the process cartridge B is regulated. The disengagement contact portion  13   f  displays its function when the process cartridge B is removed from the apparatus main assembly  14 . More specifically, when the process cartridge B is taken out of the apparatus main assembly  14 , it comes in contact with the fixing member  25  to permit a moment to function to smoothly remove the cartridge B. The steps for installing or removing the process cartridge B will be described later with reference to FIGS. 10-17. 
     Describing in more detail, a recessed portion  13   g  is provided on the cleaning unit C, on the top surface  13   i  of the cleaning unit C, at each of the lateral edges relative to the cartridge inserting direction. This recess portion  13   g  is provided with: the first slanted surface  13   g   1 , which extends upward toward the rear from the leading end of the cartridge B relative to the inserting direction (arrow X direction); the second slanted surface  13   g   3 , which extends downward toward the rear from the top end  13   g   2  of the slanted surface  13   g   3 ; and the fourth slanted surface  13   g   5 , which extends further downward toward the rear from the bottom end  13   g   4  of the slanted surface  13   g   3 . At the bottom end  13   g   6  of the slanted surface  13   g   5 , a wall (slanted or inclined surface)  13   g   7  is provided. The second slanted surface  13   g   3  corresponds to the regulatory contact portion  13   e,  and the wall  13   g   7  corresponds to the disengagement contact portion  13   f.    
     Here, the typical measurements of the portions described above will be listed. 
     The regulatory contact portion  13   e  is angled by 0 degree relative to the horizontal direction X (FIG. 5) of the cartridge B in the apparatus main assembly  14 , and is approximately 6.0 mm in length (tolerable range of 4.5 mm to 8.0 mm). The disengagement contact portion  13   f  is slanted by θ 1  (approximately 45 degrees) relative to the horizontal direction l, and is approximately 10.0 mm in length (tolerable range of 8.5 mm to 15.0 mm). 
     [Steps for Installing or Removing Process Cartridge] 
     Next, the steps for installing the process cartridge B into the apparatus main assembly  14 , or removing it therefrom, will be described with reference to FIGS. 10-19B. 
     Let it be assumed that the process cartridge B structured as described above can be installed into the cartridge accommodating means provided within the apparatus main assembly  14 , and can be removed therefrom. 
     Referring to FIGS. 18,  19 A, and  19 B, as an operator opens a pivotal cover  35  by pivoting it about a supporting point  35   a,  a cartridge accommodating space S, and left and right cartridge installation guides  16 , which are mounted on the corresponding sides of the apparatus main assembly  14 , are exposed. Each of the cartridge installation guides  16  comprises a pair of guide portions of its own, that is, a first guide portion  16   a  and a second guide portion  16   b,  which correspond to the same on the opposite side. The installation of the process cartridge B into the apparatus main assembly  14  is accomplished by inserting the process cartridge B along the guide portions  16   a  and  16   b  and closing the cover  15 . As for the inserting direction of the cartridge B, it is a direction which intersects with the axial line of the photosensitive drum  7 ; more specifically, such a direction that is substantially perpendicular to the axial line of the photosensitive drum  7  as illustrated in FIGS. 10-17. In this case, the cleaning unit C side is the leading side and the developing unit D side is the tailing side. 
     A recessed portion  17  is provided on the cartridge B, at each of the longitudinal ends, which makes it easier for an operator to hold it during its installation or removal (see FIG.  3 ); the operator uses both hands to hang onto the recessed portions, as handholds, of the process cartridge when installing or removing it. 
     Further, the process cartridge B comprises a drum shutter  18  (see FIG.  3 ), the movement of which is linked to the movement of the cartridge B during its installation or removal. When the cartridge B is removed from the laser beam printer assembly, the shutter  18  is closed to protect the portion of the photosensitive drum  7  which faces the transfer opening. This shutter member  18  is connected to each of the tips of an arm  18   a  and a link member  18   b,  being thereby supported, both of which are rotatively supported on the cleaning means frame  13  as illustrated in FIG.  6 . Also referring to FIG. 6, as the process cartridge B is inserted in the apparatus main assembly  14  in the arrow X direction, the leading end of the lever  23 , which is fixed to the arm  18   a  by its base portion, strikes a stopper (unillustrated) fixed on the apparatus main assembly  14 , whereby the lever  23  is rotated about a supporting point  18   c  where the shutter arm  18   a  is supported, opening thereby the shutter member  18 . As the process cartridge B is taken out of the apparatus main assembly  14 , the shutter member  18  is closed due to the elastic force of a torsion spring  23   a.    
     The first guide portion  16   a  is the bottom portion of the guide member  16 , and guides the long guide  12   a  and cylindrical guide  13   a  provided on the process cartridge B side. This first guide portion  16   a  comprises a main guide portion  16   a   1 , a stepped portion  16   a   2 , a recessed portion  16   a   3 , an auxiliary guide portion  16   a   4 , and a positioning groove  16   a   5 , which are disposed in this order from the upstream side toward the downstream relative to the inserting direction. The main guide portion  16   a   1  guides the long guide  12   a  and cylindrical guide  13   a.  The auxiliary guide portion  16   a   4  guides the cylindrical guide  13   a  into the positioning groove  16   a   5 . The positioning groove  16   a   5  is where the cylindrical guide  13   a  is fitted to regulate the position of the cartridge B in the apparatus main assembly  14 . The second guide portion  16   b  is the upper portion of the guide member  16 , and comprises a slanted surface  16   b   1  and a recess  16   b   2 , which are disposed in this order from the upstream side toward the downstream relative to the inserting direction. 
     Further, in the cartridge accommodating space S of the apparatus main assembly  14 , a fixed member  25  (member for regulating the rotation) is provided on the left and right sides. It is fixed to a stay  27 . This fixed member  25  comes in contact with the aforementioned regulatory contact portion  13   e  to regulate the clockwise rotation of the cartridge B (FIG.  15 ). More specifically, the cartridge B is accurately positioned in the apparatus main assembly  14  as the cylindrical guide  13   a  fits into the groove  16   a   5  and the regulatory contact  13   e  comes in contact with the fixed member  25 . Further, when the cartridge B is taken out, the fixed member  25  comes in contact with the disengagement contact portion  13   f  to facilitate the smooth removal of the cartridge B. 
     Further, in the cartridge accommodating space S, a pressing member  26  is disposed on the left and right sides (refer to FIGS.  10 - 19 B). This pressing member  26  pressed in the clockwise direction (FIGS. 10-17) by the elastic force of a coil spring  26   a  is rotatable about a fulcrum  26   b,  and elastically presses the top surface of the cartridge B, whereby the cartridge B is prevented from being vibrated when the apparatus A is subjected to vibration or the like. 
     Next, the relationship between the installation guide  16  provided on the apparatus main assembly  14  and the guide members  12   a,    13   a  and  13   b  provided on the cartridge B, during the installation or removal of the cartridge B, will be described with reference to the drawings. FIGS. 10-15 are schematic drawings, which depict the steps for installing the process cartridge B from the beginning of the cartridge installation to the moment when the process cartridge B is finally positioned in a predetermined location. In FIGS. 10 and 15, the full side view of the process cartridge B is depicted with a solid line, and the installation guide member of the apparatus main assembly  14  is depicted with a double dot chain line (imaginary line). In FIGS. 11-14, which depict intermediary steps of the cartridge installation, only the guide members of the process cartridge B are depicted with the solid line, and the other portions are depicted with the double dot chain lines. 
     First, referring to FIG. 10, at the beginning of the cartridge B installation into the apparatus main assembly  14  by an operator, the cylindrical guide  13   a  and long guide  12   a  of the cartridge B are guided by the guide portion  16   a  in such a manner as to slide thereon. At this moment, the short guide  13   b  is not guided by the guide portion  16   b,  being away from it by a predetermined distance E (in this embodiment, approximately 2.0 mm to 4.0 mm). 
     Also at this moment, the pressing member  26  rotates upward following the slanted surface  13   i  provided on the top surface of the cartridge B, so that it does not interfere with the cartridge installation. As the cartridge B is being further inserted, the pressing member  26  keeps on sliding on the top surface of the cartridge B, checking thereby the upward movement of the cartridge B. Even after the cartridge B has been installed in the apparatus A, the pressing member  26  keeps on pressing on the top surface of the cartridge B as long as the cartridge B is in the apparatus A. 
     Next, when the process cartridge B has been further inserted and is in the state depicted in FIG. 11, the cylindrical guide  13   a  is ready to pass the stepped portion  16   a   2  provided on the first installation guide portion  16   a  and to move onto the recess portion  16   a   3  provided also on the first installation guide portion  16   a.  This recessed portion  16   a   3  of the guide portion  16   a  is to let go the long guide  12   a  when the process cartridge B is inserted to a predetermined point (FIG.  15 ), and its depth m (in this embodiment, approximately 4.0 mm to 8.0 mm) is set to be larger than the aforementioned distance E (E&lt;M). It should be noted that at this moment, the short guide  13   b  is not in contact with the second guide portion  16   b  (upwardly slanted surface  16   b   1 ). 
     Next, as the process cartridge B is further inserted till the state depicted in FIG. 12 is realized, the short guide  13   b  makes contact with the guide portion  16   b  before the cylindrical guide  13   a  of the cartridge B reaches the bottom of the recessed portion  16   a   3 . 
     In other words, at this time, both the long and short guides  12   a  and  13   b  serve as the insertion guide, whereby the shock, which might be imparted on the cartridge B by the stepped portion or the like, is reduced. 
     As the process cartridge B is further inserted, the state illustrated in FIG. 13 is realized. In this state, the trailing end of the long guide  12   a  of the process cartridge B is at the edge of the recessed portion  16   a   3  of the first guide portion  16   a,  and the cylindrical guide  13   a  of the process cartridge B is in contact with the auxiliary guide portion  16   a   4 , being ready to follow the guide portion  16   a   4 . Next, the cylindrical guide  13   a  and short guide  13   b  of the process cartridge B are guided by the first guide portion  16   a  and second guide portion  16   b,  respectively (FIG.  14 ). 
     Next, as the cartridge B is further inserted and the state illustrated in FIG. 14 is realized, the short guide  13   b  comes to the recessed portion  16   b   2  of the second guide portion  16   b.  For a short period in which this short guide  13   b  drops into the recessed portion  16   b   2 , only the cylindrical guide  13   a  is in contact with the apparatus main assembly  14 , at the auxiliary guide portion  16   a   4 ; therefore, the process cartridge B slightly rotates in the counterclockwise direction, and lastly, the cylindrical guide  13   a  drops into the groove  16   a   5  of the guide portion  16   a  (FIG.  15 ). At substantially the same time, the regulatory contact portion  13   c  provided on the cleaning means frame portion  13  comes in contact with the rotation regulating portion  25   a  (FIG. 15) of the fixed member  25  fixed to the apparatus main assembly  14 . As a result, the overall position and orientation of the process cartridge B within the apparatus A is fixed. In this state, the position of the process cartridge is fixed by the cylindrical guide  13   a  alone, and the other guides (long and short guides  12   a  and  13   b ) are not in contact with any portion of the installation guide member  16  of the apparatus main assembly  14 ; therefore, the position of the cartridge B is accurately fixed. 
     The positional relationship between the regulatory contact portion  13   e  and rotation regulating portion  25   a,  which will be described later in detail, is such that the moment, which is generated on the process cartridge B as the process cartridge B is driven, is received by the contact between regulatory contact portion  13   e  and rotation regulating portion  25   a.  The distance from the contact point between the regulatory contact portion  13   e  and rotation regulating portion  25  to the center of the cylindrical guide  13   a  is longer than the distance between the long guide  12   a  and the center of the cylindrical guide  13   a,  and the distance between the short guide  13   b  and center of the cylindrical guide  13   a.  Therefore, the orientation of the process cartridge B remains more stable when the process cartridge B is driven. 
     In a state shown in FIG. 15, a helical drum gear  7   b  provided on the photosensitive drum  7 , at one of the axial ends, engages with a driving helical gear  28  provided on the apparatus main assembly  14 . Thus, the driving force is transmitted from the apparatus main assembly  14  to the photosensitive drum by way of the gears  28  and  7   b,  wherein as the driving force is transmitted from the helical gear  28  to helical gear  7   b,  the cartridge B is subjected to a force that works in the clockwise direction (FIG.  17 ). However, the movement generated on the cartridge B is regulated by the contact portion  13   e.    
     The pressing member  26  presses down the process cartridge B from above. Therefore, even if the cylindrical guide  13   a  fails to drop into the groove  16   a   5  of the apparatus main assembly  14 , a moment is generated about the contact point between the rotation regulating portion  25   a  and contact portion  13   e,  whereby the cylindrical guide  13   a  is caused to drop into the groove  16   a   5 . 
     Next, referring to FIGS. 16 and 17, the steps for taking the process cartridge B out of the apparatus main assembly  14  will be described. In the drawing, the direction indicated by an arrow Y is the direction in which the process cartridge B is removed. 
     Referring to FIG. 16, when the process cartridge B is to be removed from the apparatus main assembly  14 , the operator grabs a handle portion  17  (to provide the handle, recessed portions, are formed on the cartridge B) and lifts the cartridge B by the handle portion  17  (direction of an arrow a), whereby the process cartridge B is rotated counterclockwise about the cylindrical guide  13   a.  As a result, the disengagement contact portion  13   f  of the process cartridge B makes contact with the disengagement contact portion  25   b  of the fixed member  25  provided on the apparatus main assembly  14 . As the process cartridge B is further lifted, it is rotated about the contact point F between the disengagement contact portion  13   f  and disengagement contact portion  25   b  of the fixed member  25 . As a result, the cylindrical guide  13   a  is lifted out of the groove  16   a   5 . At this moment, the engagement between the drum gear  7   b  and driving gear  28  is smoothly broken. In this state, the process cartridge B can be pulled straight out of the apparatus A, following the steps depicted in FIGS. 14,  13 ,  12 ,  11  and  10  in that order. 
     As described above, according to this embodiment, the long guide as the second guide member is extended in the cartridge inserting direction in such a manner as to bridge the lateral surfaces of the developing unit D and cleaning unit C; therefore, the process cartridge is prevented from wobbling during the installation or removal. As a result, the cartridge installation becomes more reliable, which improves the operational efficiency. 
     The guiding means, which serves as the guide when the process cartridge is inserted into the apparatus main assembly  14  or removed therefrom, is constituted of three guide members: cylindrical guide  13   a,  long guide  12   a,  and short guide  13   b,  and the process cartridge B is guided by at least two guides during its installation or removal; therefore, even if there is a stepped portion or the like on the installation guide members of the apparatus main assembly  14 , the shock, to which the process cartridge B might be subjected, is cushioned. 
     The position of the process cartridge B is fixed by the rotation regulating portion  25   a  oriented to control the moment, which is generated on the cartridge B as the cartridge is driven, and the cylindrical guide  13   a,  whereas the other guides (long and short guides  12   a  and  13   b ) remain in non-contact with the guide members of the apparatus main assembly  14 ; therefore, the orientation of the process cartridge B remains more stable while the image forming apparatus is driven (during the image formation). 
     As for the guiding means for installing or removing the cartridge B, the embodiment described above exemplifies a guiding means comprising three guide members positioned at different locations. However, the embodiment described above is not limited to this example, but instead, it may be a guiding means comprising at least a cylindrical guide as the first guide member, and a long guide as the second guide member, or a guiding means comprising an additional guide member or guide members besides the three mentioned above. Such an arrangement can also stabilize the cartridge B during the installation or removal, and improves the operational efficiency. 
     Referring to FIGS. 9A and 9B, a spur gear  7   n  is disposed on the photosensitive drum  7 , at the end opposite, relative to the axial direction, to the end where the drum gear  7   b  is disposed. When the process cartridge B is mounted in the apparatus main assembly  14 , this spur gear  7   n  engages with a gear (unillustrated), which is disposed in the apparatus main assembly  14  on the same axis as the transfer roller  4 . As it engages with the unillustrated gear, the driving force is transmitted from the process cartridge to rotate the transfer roller  4 . 
     A reference numeral  9   u  designates a helical gear, which is disposed at one of the axial ends of the developing roller  9   c.  It engages with the aforementioned spur gear  7   b,  whereby the driving force for rotating the developing roller  9   c  is transmitted by way of the helical drum gear  7   b.    
     [Toner Container Frame (Toner Container)] 
     Referring to FIGS. 3,  29 ,  30 ,  32  and  33 , a toner container frame (toner container) will be described in detail. FIG. 29 is a perspective view before a toner seal is welded; FIG. 30, a perspective view after the toner is filled; FIG. 32, a plan view a top frame  11   a;  and FIG. 33 is a perspective view of the disassembled toner container frame. 
     A toner container frame  11  is constituted of two components: a top frame  11   a  (first frame) and a bottom frame  11   b  (second frame). On each of the longitudinal end surfaces of the top frame  11   a,  a recessed portion  17  is provided. It is disposed close to the top surface of the top frame, and serves as the handhold described above. The bottom frame  11   b  is provided with a number of ribs  11   c.  They are disposed in parallel to the longitudinal direction of the process cartridge B, with intervals of approximately 5 mm, on the exterior surface, which becomes the bottom portion when the process cartridge B is assembled. When grasping the process cartridge B, the operator uses both hands, holding onto the recessed portion  17  and ribs  11   c.  In this case, the ribs  11   c  prevent the hands from slipping when grasping the process cartridge B. The top and bottom frames  11   a  and  11   b  are joined at a welding surface U, and the welding rib is melted by forced vibration, welding the frames  11   a  and  11   b  together. The methods for joining two frames are not limited to the forced vibration method. For example, they may be welded using heat welding, ultrasonic welding, or the like, or may be simply glued. Before joining two frames  11   a  and  11   b,  the stirring member  9   b  is assembled into the top frame  11   a,  and then a coupling member  11   e  is put through a hole  11   e   1 , and engaged to the end portion of the stirring member  9   b  (state illustrated in FIG.  29 ). The hole  11   e   1  is located at one of the longitudinal ends of the top frame  11   a.  On the same side as this hole  11   e   1 , a toner filling opening  11   d  for filling the toner is located. The diameter of this toner filling opening  11   d  is approximately 30 mm. In other words, the hole  11   e   1  and toner filling opening  11   d  are located next to each other. The toner frame  11  is provided with an opening  11   i  for feeding the toner from the toner frame  11  to the developing frame  12 , and a seal, which will be described later, is welded to cover this opening  11   i.  After the seal is welded, the toner is filled through the toner filling opening  11   d,  and then the toner filling opening  11   d  is covered with a toner cap  11   f,  completing a toner unit J. The toner cap  11   f  is formed of soft material such as polyethylene or polypropylene, and is pressed into the toner filling opening  11   d  of the toner frame  11  so that it does not come off. Next, the toner unit J is joined with the developing frame  12 , which will be described later, using ultrasonic welding, constituting a part of a completed developing unit D. The joining methods are not limited to ultrasonic welding. They may be glued together, or may be snap-fitted using the elasticity of their materials. 
     Referring to FIG. 3, the angle θ of a slanted surface K, constituting a part of the bottom frame  11   b  of the toner frame  11 , must be such an angle that the toner located in the deeper end of the toner chamber slides down, naturally and continuously, in response to toner consumption. More specifically, the angle θ is the angle formed between the slanted surface K of the process cartridge B and the horizontal surface Z, with the apparatus main assembly  14  being leveled. The preferable value for the angle θ is approximately 60 degrees. When rotating, the stirring member  9   b  reaches beyond the plane of the slanted surface K. Therefore, the bottom frame  11   b  is provided with a recessed portion  11   g  to afford a clearance for the rotating stirring member  9   b;  it bulges outward. The rotational diameter of the stirring member  9   b  is approximately 30 mm. (According to this embodiment, the bottom surface of the bottom frame  11   b  dips approximately 3.6 mm. The depth of this recessed portion has only to be approximately 2.0 mm to 10 mm.) The reason for this arrangement is as follows. If the sweeping area of the stirring member  9   b  is above the slanted surface K, it is possible that the toner settling between the tip of the toner feeding (stirring) member  9   b  and the slanted surface K is not fed into the developing frame  12 , being left unused. However, in this embodiment, the toner is reliably fed from the toner frame  11  into the developing frame  12 . 
     Referring to FIG. 29, the stirring member  9   b  is formed of a rod of steel or the like material, having a diameter of approximately 3 mm and being in the form of a rectangular frame to improve toner stirring/feeding performance. Each of the opposing longitudinal ends of the stirring member  9   b  is provided with a supporting axis  9   b   1 . The supporting axis  9   b   1  on one end is fitted in a hole  11   r,  which is located on the internal surface of the top frame  11   a,  adjacent to the opening  11   i  of the top frame  11   a,  and the supporting member  9   b   1  on the other end is fixed to the coupling member  11   e.    
     As described above, the toner frame  11  is constituted of two members, that is, the top and bottom frames  11   a  and  11   b,  and the bottom wall of the bottom frame  11   b  is provided with the recessed portion  11   g  to afford a clearance for the toner feeding member  9   b;  therefore, it is possible to provide even a large capacity process cartridge with reliable toner feeding performance, without increasing cost. 
     The foregoing can be summarized as follows. 
     The toner frame (toner container)  11  constitutes a part of a replaceable process cartridge for an electrophotographic image forming apparatus, which comprises an electrophotographic photosensitive member ( 7 ,  7   e ), and developing means  9  for developing the latent image formed on the electrophotographic photosensitive member. It stores the toner used in the developing means  9  for developing the latent image, and comprises the top frame  11   a,  and the bottom frame  11   b  which is joined with the top frame  11   a.  The top frame  11   a  comprises the opening  11   i  for supplying the stored toner to the developing means  9 , and a stirring member mount  9   b   1  (FIG. 29) where the stirring member  9   b  for stirring the stored toner is rotatively mounted. The bottom frame  11   b  is provided with the recessed portion  11   g  (as seen from within), that is, a bulge (as seen from outside), to afford the clearance for the sweeping area of the stirring member  9   b.  Further, the top frame  11   a  is provided with the welding surface U (joining surface) where the bottom frame  11   b  is welded (FIGS. 29,  33  and  36 ). The angle of this welding surface, that is, the angle which is formed between this welding surface and the horizontal line  12  when the shorter edge of the rectangular opening  11   i  (FIG. 29) is vertically oriented, is approximately 20 to 40 degrees. Further, the top frame  11   a  is provided with the hole  11   e   1  (transmission opening), through which the coupling member  11   e  (transmission member) for transmitting the driving force from the apparatus main assembly to the stirring member  9   b,  when the process cartridge is in the image forming apparatus, is put. One end of the coupling member  11   e  is engaged with the stirring member  9   b,  and the other end is engaged with the toner feeding gear  9   s  to receive the driving force. The stirring member  9   b  is formed of a metallic rod, and is in the form of a rectangular frame. Further, the top frame  11   a  is provided with the toner filling opening  11   d  (filling opening), which is disposed next to the hole  11   e   1  (FIG.  29 ). It is to this toner filling opening  11   d  that the toner cap  11   f  for sealing the toner filling opening  11   d  is attached. Further, the top frame  11   a  is provided with a groove  11   n  which extends in parallel to the plane of the opening  11   i.  This groove  11   n  is where the developing frame  12 , in which the developing roller  9   c  of the developing means  9  is mounted, is joined. Further, the top frame  11   a  is provided with a cover film plate  53  (seal mount) where a cover film  51  for sealing the opening  11   i  and a tear tape  52  (toner seal) for unsealing the opening  11   i  are attached. The cover film plate  53  is also in parallel to the plane of the opening  11   i.  Further, the top frame  11   a  is provided with the handhold (recessed portion)  17 , which is where the longitudinal end surfaces of the process cartridge are indented to offer the handhold. The recessed portion  11   g  (bulge) of the bottom frame  11   b  is in the form of a longitudinally sliced cylinder, having an arc shaped cross section. It is disposed close to the opening  11   i,  relative to the widthwise direction of the bottom frame  11   b,  and extends in the longitudinal direction of the opening  11   i,  along substantially the entire length the opening  11   i.  Further,the top frame  11   a  is provided with a slanted surface L. The angle of the slanted surface L, that is, the angle which is formed between this slanted surface L and the vertical line when the shorter edge of the opening  11   i  is vertically oriented, is approximately 10 to 40 degrees (FIG.  36 ). This slanted surface L is located above the opening  11   i,  sloping down toward the opening  11   i  and extending in parallel to the longitudinal direction of the opening  11   i,  along substantially the entire length of the opening  11   i.    
     The toner frame (toner container)  11  is assembled in the following manner. First, the top frame  11   a,  which is provided with the opening  11   i  for supplying the stored toner into the developing means  9 , and the stirring member mount  9   b   1  where the stirring member  9   b  is mounted, is prepared. Next, the bottom frame  11 , which is provided with the recessed portion  11   g  bulging outward to afford the clearance to the sweeping area of the stirring member  9   b,  is prepared. Finally, the two frames,  11   a  and  11   b,  are joined to complete the toner frame (toner container)  11 . 
     It is predictable that the toner within the toner frame  11  will move suddenly due to vibration, impact, or the like, during the shipment of the process cartridge B from factory to user. 
     Therefore, according to the present invention, plural partitioning plates  11   p  are provided within the top frame  11   a  of the toner frame  11 . 
     They are arranged in the longitudinal direction of the top frame  11   a  (FIGS. 3,  32  and  33 ). In this embodiment, three partitioning plates  11   p  are disposed at three different locations. As for the configuration of the partitioning plate  11   p,  the edge  11   p   1  facing the toner feeding member  9   b  forms a substantial quadrant in such a manner as to surround the toner feeding member  9   b,  and the edge  11   p   2  facing the bottom frame  11   b  holds a slight gap therefrom. Further, as seen from the longitudinal direction of the top frame  11   a,  the edge  11   p   1  is positioned so that the partitioning plate  11   p  partially blocks the toner filling opening  11   d.    
     In order to prevent the toner from shifting within the toner container  11 A, the partitioning plate  11   p  should be as large as possible. However, when the toner filling opening  11   d  is faced upward to fill the toner, the partitioning plate  11   p  is situated directly below the toner filling opening  11   d,  and if the partitioning plate  11   p  blocks the toner filling opening  11   d  entirely, it is difficult to fill the toner into the deepest corner of the toner container  11 A. Therefore, the partitioning plate  11   p  should be formed as it is in this embodiment, so that the toner can be filled all the way into the deepest corner through the space which is not blocked by the partitioning plate  11   d.  Further, according to the present invention, the partitioning plate  11   p  occupies a substantial part of the cross-sectional area perpendicular to the longitudinal direction of the toner frame  11 ; therefore, even when the process cartridge B is subjected to vibration, impact, or the like, the partitioning plate  11   p  can prevent the toner from shifting and becoming compacted. 
     [Toner Frame Structure Facing Developing Frame] 
     Referring to FIGS. 29,  31 A, and  31 B, at the joint between the toner frame  11  and developing frame  12 , the opening  11   i  for feeding the toner from the toner frame  11  into the developing frame  12  is provided. The opening  11   i  is surrounded by a recessed surface  11   k,  on which the cover film plate  53  is thermally welded. The depth of this recessed surface  11   k  is such that after the cover film plate  53  is welded to the recessed surface  11 , the outward facing surface of the cover film plate  53  becomes substantially level with the surface  11   j  of the toner frame  11  (top frame  11   a ). On the recessed surface  11   k,  plural dowels  11   m  are disposed in a straight line along one of the longitudinal edges of the opening  11   i  (in this embodiment five dowels  11   m  are disposed at five different locations). Also, two dowels  11   o  are disposed on the surface  11   j  along one of the widthwise edges of opening  11   i;  these two dowels  11   o  are not on the recessed surface  11   k.  Further, along each of the longitudinal external edges of the surface  11   j,  a groove  11   n  is disposed in parallel to the one on the opposing side. The bottom surface  11   n   2  of this groove  11   n  is above the level of the surface  11   j  (closer to the developing frame  11  than the surface  11   i ) (FIGS.  31 A and  31 B). 
     The surface of the developing frame  12 , which comes directly in contact with the surface of the toner frame  11 , is a surface  12   u.  Along each of the longitudinal edges of this surface  12   u,  a tongue  12   v,  which fits into the groove  11   n  of the toner frame  11 , is provided. At the end surface of this tongue  12   v,  an angular ridge  12   v   1 , used for ultrasonic welding, is provided (FIGS.  31 A and  31 B); the angular ridge  12  is melted by ultrasonic welding to weld the toner frame  11  and developing frame  12 , along their longitudinal external edges. 
     Referring to FIG. 30, the cover film plate  53 , which is loosely fitted onto the recessed surface  11   k  of the toner frame  11 , is provided with holes  53   c,  which correspond to the plural dowels  11   m.  The holes  53   c   1 , which exactly fit to the corresponding end dowels  11   m   1 , are round, and the holes  53   c  other than the round holes  53   c   1  are elongated so as to be loosely fitted to the corresponding dowels  11   m  other than the end dowels  11   m   1 . More specifically, the positional relationship between the dowels  11   m  and hole  53   c  is such that when the dowels  11   m   1  and  11   m  are fitted in the corresponding holes  53   c   1  and  53   c,  the dowel  11   m  is positioned at the middle of the elongated holes  53   c  in the longitudinal direction of the elongated holes  53   c.  Further, the cover film plate  53  is provided with an opening  53   b  (having approximately the same size as the opening  11   i ), which corresponds to the opening  11   i . In order to seal this opening  53   b,  a cover film  51 , which can be easily torn in the longitudinal direction, is pasted on the cover film plate  53 ; the four peripheral areas of the cover film  51  are pasted on corresponding four peripheral areas of the opening  53   b.  On the cover film  51 , the tear tape  52  for tearing the cover film  51  to unseal the opening  53   b  is welded. The tear tape  52  is extended from one of the longitudinal ends of the opening  53   b  to the other end, where it is doubled back and put through the starting end, between the toner frame  11  and an elastic seal member  54  (FIG.  27 ), such as a piece of felt, which is pasted on the flat developing frame surface  12   u , directly facing the toner frame  11 , at the starting end. The doubled back end of the tear tape  52  is exposed from between the toner frame  11  and developing frame  12  (FIGS.  6  and  30 ). On the inward side surface of the seal member  54 , a synthetic resin film tape  55  with a small friction coefficient is pasted. Also on the flat surface  12   u,  an elastic seal member  56  is pasted at the longitudinal end opposite from where the seal member  54  is pasted (FIG.  27 ). 
     In order to make it easier to align the toner frame  11  and developing frame  12  when joining two frames  11  and  12 , the surface  11   j  of the toner frame  11  is provided with a round hole  11 r and a square hole  11   q , which engage with a cylindrical dowel  12   w   1  and square column dowel  12   w   2 , respectively, provided on the developing frame  12 ; the round hole  11   r  engages with the dowel  12   w   1 , and the square hole  11   q  loosely engages with the dowel  12   w   2 . The seal member  56  is fitted around the cylindrical dowel  12   w   1 , and also is glued to the flat surface  12   u . Further, in the flat surface  12   u  of the developing frame  12 , which directly comes in contact with the toner frame  11 , recessed portions  12   y  are provided, in which the dowels  11   m  and  11   o  of the toner frame  11  loosely fit. 
     Before the toner frame  11  and developing frame  12  are joined, each frame is independently assembled as a subcomponent. Thereafter, the cylindrical positioning dowel  12   w   1  and square column positioning dowel  12   w   2  of the developing frame  12  are fitted into the round positioning hole  11   r  and square positioning hole  11   q  of the toner frame  11 , respectively. Also, the tongue  12   v  of the developing frame  12  is fitted into the groove  11   n  of the toner frame  11 . Then, as the toner frame and developing frame  12  are pressed together, the seal members  54  and  56  are compressed, and ridges  12   z , which are integrally formed as spacers with the developing frame, at each of the longitudinal ends, approach the surface of the toner frame  11 . The ridges  12   z  are aligned in the widthwise direction of the developing frame  12 , with an interval substantially equal to the width of the tear tape  52 , to allow the tear tape  52  to be put through. With the toner frame  11  and developing frame  12  being pressed together as described above, ultrasonic vibration is applied between the tongue  12   v  and groove  11   n,  whereby the angular ridge  12   v   1  is melted and welded to the bottom of the groove  11   n  by the frictional heat. As a result, the edges  11   n   1  of the grooves  11   n  of the toner frame  11 , and the ridges  12   z , as the spacers, of the developing frame  12 , firmly contact their counterparts, sealing the entire joint between the toner frame  11  and developing frame  12 , except for the gap left between the surface  11   j  of the toner frame  11  and the flat surface  12   u  of the developing frame  12 . The cover film  51  and tear tape  52  are confined in this gap. 
     In order to feed the toner stored in the toner frame  11  into the developing frame  12 , the operator has only to pull the end portion  52   a  (FIG. 6) of the tear tape  52 , which is exposed from the process cartridge B, by hand. As the tear tape  52  is pulled, the cover film  51  is torn open to unseal the opening  53   b  ( 11   i ), allowing the toner to be fed from the toner frame  11  into the developing frame  12 . 
     Since the joining portions of the toner frame  11  and developing frame  12  are structured as described in the foregoing, that is since the surface of the cover film plate  53  and the surface  11   j  of the toner frame  11  are substantially at the same level, the tear tape  52  can be smoothly pulled out from between the two frames  11  and  12  by applying to the tear tape  52  a sufficient amount of force for tearing the cover film  51  as described above. The cover film plate  53  is located by the dowel  11   m   1  at one of its longitudinal ends, that is, the end opposite to where the tear tape  52  is pulled out, and in addition, it is disposed on the recessed surface  11   k  of the toner frame  11 ; therefore, it is not liable to be dislocated. Further, the dowels  11   m  are aligned in a straight line in the longitudinal direction, and the cover film plate  53  is fitted to these dowels  11   m ; therefore, even the easily deformable cover film  51  can be precisely located to allow it to remain flat. Further, even if the assembly process moves on to the subsequent steps before the welded joint between the cover film plate  53  and toner frame  11  is solidified and stabilized, the cover film plate  53  is not dislocated. 
     When the toner frame  11  and developing frame  12  are joined using ultrasonic welding method, frictional heat is generated to melt the angular ridge  12   v   1 . This frictional heat is liable to cause thermal stress in the toner frame  11  and developing frame  12 , which might result in the thermal deformation of the toner frame  11  and developing frame  12 . However, according to this embodiment, the groove  11   n  of the toner frame  11  and the tongue  12   v  of the developing frame  12  are engaged across substantially the full length in the longitudinal direction. In other words, the joint portions between the toner frame  11  and developing frame  12  are reinforced as to frames  11  and  12  are joined; therefore, the thermal deformation due to the thermal stress is not likely to occur. 
     As described above, the grooves  11   n , handholds (recessed portions)  17 , partitioning plates  11   p , toner filling opening  11   d,  hole  11   e   1 , round hole  11   r , square hole  11   q , and cover film plate mount (recessed surface  11   k , dowels  11   m  and opening  11   i ), of the top frame  11   a  are integrally formed with the top frame  11   a . Also, the ribs  11   c  and recessed portion  11   g , of the bottom frame  11   b  are integrally formed with the bottom frame  11   b . The material for the top and bottom frames  11   a  and  11   b  is a plastic material, for example, polyethylene, ABS resin (acrylonitrile-butadiene-styrene copolymer), polycarbonate. polyethylene, and polypropylene. 
     FIG. 36 is a side view of the toner frame  11  used in this embodiment; the surface  11   j  of the toner frame  11 , which is joined with the developing frame  12 , is vertically oriented. 
     The toner frame  11  employed in this embodiment is provided with two slanted surfaces K and L, which allow the toner (single component toner) stored in the storage portion  11 A to efficiently descend toward the opening  11   i.  Both slanted surfaces K and L extend across the entire longitudinal length of the toner frame  11 . The slanted surface L is located above the opening  11   i , and the slanted surface K is located immediately behind the opening  11   i  (being slanted in the widthwise direction of the toner frame  11 ). The slanted surface L belongs to the top frame  11   a,  and the slanted surface K is formed as a part of the structure of the bottom frame  11   b.  The angle θ 2  of the slanted surface L relative to a vertical line  11  (joining surface  11   j ) is approximately 10 degrees to 40 degrees (in this embodiment, θ 2  is set at 24 degrees). The angle θ 3  of the slanted surface K, relative to the horizontal plane  12 , perpendicular to the vertical line  11 , is approximately 20 to 40 degrees (in this embodiment, θ 3  is set at approximately 27 degrees). In other words, the configuration of the top frame  11   a  in this embodiment is regulated so that when the bottom frame  11   b  is joined with the top frame  11   a,  the joined bottom frame  11   b  holds the aforementioned angle. Therefore, even if the toner storage portion  11 A is such a toner storage portion that contains a large amount (for example, no less than 800 g), the toner can be efficiently fed toward the opening  11   i.    
     Next, the developing frame will be further described in detail. 
     [Developing Frame] 
     The developing frame will be described with reference to FIGS. 3,  26 ,  27  and  28 . FIG. 26 is an exploded perspective view of the developing frame  12 , illustrating how the components are assembled; FIG. 27, a perspective view of the developing frame  12  and toner stirring member  9   e  and  9   f,  as seen from the direction of the surface to be welded, illustrating how the stirring members  9   e  and  9   f  are assembled into the frame  12 ; and FIG. 28 is a perspective view of the developing unit without the developing frame holder. 
     As described above, the developing roller  9   c,  developing blade  9   d,  toner stirring members  9   e  and  9   f,  and antenna rod  9   h  for detecting the amount of the remaining toner, are assembled into the developing frame  12 . 
     The developing blade  9   d  comprises a 1-2 mm thick metallic plate  9   d   1 , and a urethane rubber blade  9   d   2  fixed to the metallic plate  9   d   2  by means of hot melting, double-side adhesive tape, or the like. It regulates the amount of toner coated on the peripheral surface of the developing roller  9   c.  The flatness of a blade accommodating flat surface  12   i , as a blade mount, provided on the developing frame  12  is regulated; it is approximately 0.05 mm. This flat surface  12   i  is provided with dowels  12   i  and screw holes  12   i   2 . The dowels  12   i   1  are fitted into the holes  9   d   3  provided on the metallic plate  9   d   1 . Thereafter, the metallic plate  9   d   1  is screwed onto the flat surface  12   i , using the screw holes  9   dr  provided on the metallic plate  9   d   1 , and the screw holes  12   i   2 . Also on the developing frame  12 , an elastic seal member  12   s  formed of MOLTPLANE or the like is pasted to prevent toner invasion. It is disposed above the metallic plate  9   d   1 , extending in the longitudinal direction thereof. In addition, an elastic seal member  12   s   1  is pasted on the developing member, at each of the longitudinal ends, covering from both ends of the elastic seal member  12   s  to a round surface  12   j , which follows the contour developing roller  9   c.  Further, on the mandible-like portion  12   h , a thin elastic seal member  12   s   2  is pasted. This elastic seal member  12   s   2  contracts the generatrix of the developing roller  9   c.    
     One  9   d   1   a  of the longitudinal ends of the developing blade  9   d  is bent by approximately 90 degrees. This bent portion  9   d   1   a  equalizes the voltages of the metallic plate  9   d   1  and developing roller  9   c  by contacting a development bias contact point  121  (FIGS.  23 (A) and  23 (B)), supported on a developing frame holder  40  which will be described later. This arrangement is made because the amount of the toner is detected on the basis of the change in the capacitance between the antenna rod  9   h  for detecting the amount of the remaining toner, and the developing roller  9   c,  and this capacitance must be prevented from irregularly changing due to the influence of the metallic plate  9   d   1 . 
     Next, a developing roller unit G will be described. The developing roller unit G comprises: (1) developing roller  9   c;  (2) spacer roller  9   i  for keeping constant the distance between the peripheral surface of the developing roller  9   c  and the peripheral surface of the photosensitive drum  7 ; (3) developing roller bearing  9   j  for locating the developing roller  9   c  on the developing frame  12 ; (4) sleeve cap  9   o  which is placed on both ends of the developing roller  9   c  so that leakage does not occur between the aluminum cylindrical portion of the photosensitive drum  7  and the aluminum cylindrical portion of the developing roller  9   c;  (5) developing roller gear  9   k  (helical gear) which rotates the developing roller  9   c  as it receives the driving force from the helical gear  7   b  mounted on the photosensitive drum  7 ; (6) coil spring contact point  91 , one end of which is in engagement with the developing roller gear  9   k  mounted at one end of the developing roller gear  9   k ;and (7) magnet  9   g  which is contained in the developing roller  9   c  to adhere the toner to the peripheral surface of the developing roller  9   c.  This developing unit G is attached to the developing roller mount  12 X of the developing frame  12  in the following manner. First, a hole  9   j   1  provided on each of the developing roller bearings  9   j  is aligned with the hole  12   p  provided at each of the longitudinal ends of the developing frame  12 , and a pin provided on the development holder  40 , which will be described later, is inserted through the holes  9   j   1  and  12   d . Then, the developing frame holder  40  is fixed to the developing frame  12  using screws. 
     As described above, in this embodiment, when the developing roller  9   c  is mounted on the developing frame  12 , the developing roller unit G is assembled first. Then, the assembled developing roller unit G is mounted on the developing frame  12  with the use of developing frame holder  40 . By going through these steps, assembly efficiency is improved compared to the case in which the developing roller  9   c  alone is directly mounted on the developing frame  12 . 
     The developing roller unit G is assembled through the following steps. To begin with, each end of the developing roller  9   c  is covered with the sleeve cap  9   o . Next, the spacer roller  9 i is mounted at each end of the developing roller  9   c;  the spacer roller  9   i  is placed on the outward side of the sleeve cap  9   o . Then, the developing roller bearing  9   j  is mounted on the outward side of the spacer roller  9   i . Next, the developing roller gear  9   k  is mounted at one of the longitudinal ends of the developing roller  9   c,  on the outward side of the bearing  9   j , and the coil spring contact point  91  is mounted on the further outward side. At this point in the assembly, one end  9   g   1  of magnet  9   g , which has a D-shaped cross section, projects from one end of the developing roller  9   c,  that is, the end where the developing roller gear  9   k  is mounted, and the other end of the magnet  9   g , which is cylindrical, projects from the other end of the developing roller  9   c.  This is the way developing roller unit G is assembled. 
     Next, the antenna rod  9   h  for detecting the amount of the remaining toner will be described. One end of the antenna rod  9   h  is U-shaped. This U-shaped portion  9   h   1  is placed in contact with, being thereby electrically connected to, the toner detection contact point  122  mounted on the developing frame holder  40  which will be described later. This antenna rod  9   h  is attached to the developing frame  12  in the following manner. First, the end portion  9   h   3  of the antenna rod  9   h  is inserted into the developing frame  12  through a through hole  12   b , provided on the side plate  12 A of the developing frame  12 . Then, the inserted end portion  9   h   3  is put through a through hole  12   k  provided on the other side plate of the developing frame  12 , being supported thereby. In other words, the antenna rod  9   h  is located and supported by the through holes  12   b  and  12   k . In the through hole  12   b , a seal member (unillustrated) formed of felt, sponge, or the like, is inserted to prevent toner invasion. 
     Further, the tip portion  9   h   2  of the U-shaped portion  9   h   1  is inserted into an approximately 5 mm deep hole  12   o  of the developing frame  12  to locate the antenna rod  9   h  in the axial direction. Also, this arrangement improves the rigidity of the U-shaped portion  9   h   1  as the contact point which contacts the toner detection contact point  122  which will be described later. The through hole  12   k , into which the end portion  9   h   3  of the antenna rod  9   h  has been inserted is plugged from outside using thermal welding or the like method, so that toner invasion can be prevented. Next, the toner stirring members  9   e  and  9   f  will be described. The toner stirring members  9 e and  9   f  are shaped like a crank and stir the toner as they rotate. They are disposed near the developing roller  9   c  and antenna rod  9   h , across the toner path which the toner having been stored in the toner container  11 A passes as it is fed toward the developing roller  9   c.  The toner stirring members  9   e  and  9   f  are fixed perpendicular to each other. 
     In assembling the toner stirring members  9   e  and  9   f  onto the developing frame  12 , to begin with, the end portions  9   e   3  and  9   f   3  of the toner stirring members  9   e  and  9   f , respectively, are inserted through corresponding through holes  12   t  and  12   r  provided on the side plate  12 A of the developing frame  12 , which is on the same side as the one through which the antenna rod  9   h  is inserted. Then, the end portions  9   e   3  and  9   f   3  are inserted into corresponding through holes  12   m  and  12   n , provided on the side plate  12 B, which is the opposite side plate of the side plate  12 A. Thereafter, each of the through holes  12   m  and  12   n  are plugged from outside by the thermal welding method, as are the through holes  12   k  for the antenna rod  9   h . After the stirring members  9   e  and  9   f  are inserted into the developing frame  12  as described above, stirring gears  9   m  and  9   n  are fitted into the through holes  12   t  and  12   r . At this time, notches  9   m   1  and  9   n   1 , which are cut in the axial direction at the end portions of the gears  9   m  and  9   n , respectively, are engaged with the crank arms  9   e   2  and  9   f   2  of the toner stirring members  9   e  and  9   f , respectively. Further, the journals  9   e   1  and  9   f   1  of the stirring members  9   e  and  9   f  are fitted into center holes (unillustrated) provided at the deeper ends of the notches  9   m   1  and  9   n   1  of the gear  9   m  and  9   n , respectively, supporting thereby the toner stirring members  9   e  and  9   f  on the developing frame  12 . 
     When the toner frame  11  and developing frame  12  are joined, the side plate  12 A of the developing frame  12 , which is located on the side from which the antenna rod  9   h  and toner stirring members  9   e  and  9 f are inserted, overlaps the side plate of the toner frame  11 , covering the toner cap  11   f  provided on the top frame  11   a  of the toner frame  11 . Also, on the side plate  12 A, a hole  12   x  is provided, in which a toner feeding gear  9   s  (FIG. 28) for transmitting the driving force to the toner feeding member  9   b  is rotatively fitted. The toner feeding gear  9   s  is linked with the coupling member  11 e (FIGS.  29  and  30 ), which is rotatively supported by the toner frame  11   a  and is engaged with the end portion of the toner feeding member  9   b,  whereby the driving force is transmitted to the toner feeding member  9   b.    
     Next, how the driving force is transmitted will be described. 
     Referring to FIGS. 28 and 35, the stirring gears  9   m  and  9   n , and the toner feeding gear  9   s , receive the driving force from the developing roller gear  9   k . More specifically, to begin with the stirring gear  9   m  receives the driving force through a small gear  9   g   1  of an idler gear  9   q  as a stepped gear. Receiving this driving force, the stirring member  9   e  rotates. The idler gear  9   g  receives the driving force from the developing roller gear  9   k  since the large gear  9   g   3  of the idler gear  9   g  meshes with the developing roller gear  9   k . The received driving force is transmitted from the middle gear  9   g   2  of the idler gear  9   g  to an idler gear  9   r  as a stepped gear. Then, the driving force is further transmitted from the small gear  9   r   1  of the idler gear  9   r  to the toner feeding gear  9   s , rotating thereby the stirring member  9   b  (through the coupling member lie). Further, the driving force is transmitted from the toner feeding gear  9   s  to the stirring gear  9   n  by way of an idler gear  9 t to rotate the stirring member  9   f . It should be noted here that all the idler gears,  9   q ,  9   r  and  9   t , are rotatively mounted on corresponding dowels,  12   e    12   f  and  12   g , which are integrally formed with the developing frame  12 . These dowels  12   e ,  12   f  and  12   g  are approximately 2 mm to 3 mm in diameter, and their end portions are supported by the developing frame holder  40  which will be described later; therefore, the dowels  12   e ,  12   f  and  12   g  do not deform due to load. Further, the rigidity of dowels  12   e ,  12   f  or  12   g  is increased by padding or stepping their base portions, or the like means. 
     The gear train described above is disposed on the same side surface as the previously described U-shaped portion  9   h   1  of the anttena  9   h.    
     With the adoption of the above structure, a single member (in this embodiment, the developing frame holder  40 ) can support the gears constituting the gear train, and establish electrical connection for the toner remaining detecting contact point. In addition, all of the toner stirring members  9   e  and  9   f,  antenna rod  9   h , gears  9   o ,  9   r ,  9   s  and  9   t  constituting the gear train, and stirring gears  9   m  and  9   n , can be assembled into the developing frame  12  from the same side relative to the longitudinal direction of the developing frame  12 . Therefore, assembly effeciency can be greatly improved. 
     The mandible-like portion  12   h  of the developing frame  12  doubles as a conveying guide for the recording medium  2 , such as recording paper. In order to increase the rigidity, the developing frame  12  may be formed using the blow molding method. 
     Referring to FIG. 27, a reference numeral  12 P designates an opening which extends in the longitudinal direction of the developing frame  12 . As the toner frame  11  and developing frame  12  are joined, this opening  12 P aligns with the opening  11   i  of the toner frame  11 , allowing the toner stored in the toner frame  11  to be supplied to the developing roller  9   c.  The aforementioned stirring members  9   e  and  9   f , and antenna rod  9   h , are mounted across the entire longitudinal length of this opening  12 P. 
     Further, according to this embodiment, the developing frame  12  comprising the developing roller mount  12 X, side plate  12 A, developing blade mount (blade accommodating flat surface  12   i ), antenna rod  9   h  mount (through holes  12   b ,  12   k  and  12   o ), stirring member mount (through holes  12   t ,  12   r ,  12   m  and  12   n ), gear mount (dowels  12   e ,  12   f  and  12   g ),and the like, is integrally formed with these portions. The material for the developing frame  12  is the same as the aforementioned material for the toner frame  11 . 
     [Developing frame holder  40 ] 
     Next, the developing frame holder  40  will be described. 
     Referring to FIGS. 4-9 and FIGS. 23A-25, description will be given as to the developing frame holder  40 . FIG. 23A is a perspective view of the developing frame holder, which is mounted on the driving side, as seen from the outside of the developing frame  12 ; FIG. 23B a perspective view of the same as seen from inside; FIG. 24, an enlarged sectional view of the FIG. 23B at (I)—(I) line; and FIG. 25 is an enlarged perspective view of the toner detecting contact point. 
     The developing unit D is completed by attaching the development holders  40  and  41  at the corresponding lateral ends of the developing frame assembly, having been finished up to the stage illustrated in FIG.  28 . In this case, the developing roller unit G is mounted in the following manner. First, one of two pins  40   d  provided at different locations of the developing frame holder is engaged with the hole  9   j   1  of the aforementioned developing roller bearing, and the other pin  40   d  is engaged with the hole  12   p  of the developing frame  12 . Next, the developing frame holders  40  and  41  are fixed to the developing frame  12  with screws, in such a manner that the developing roller bearings  9   j  are sandwiched between the corresponding developing frame holders  40  and  41 , and the developing frame  12 . At this time, the screws are put through the corresponding holes  401  of the holders  40  and  41 . Next, one end  9   g   1  of the magnet  9   g  (FIGS. 3 and 28) contained in the developing roller  9   c  is engaged with a D-shaped hole  40   e  provided on the developing frame holder  40 , and the other end  9   g   2  is engaged with a hole (unillustrated) provided on the developing frame holder  41 , whereby the position of the magnet  9   g  in the longitudinal direction is fixed. The angles of the magnetic poles of the magnet  9   g  are determined as the end portion  9   g   1 , having the aforementioned D-shaped section, is engaged with the D-shaped hole  40   e  of the developing frame holder  40 . 
     Next, rotational shafts  20 , which are integrally formed with the developing frame holders  40  and  41  and project therefrom, are placed into recessed portions  21  (FIG. 9B) of the cleaning frame, and covered with connector members  22  (FIG.  7 ), whereby the developing unit D is rotatively supported on the cleaning frame  13  which supports the photosensitive drum  7  and in addition, the compression spring  22   a  attached to the connector members  22  is compressed against the spring seats  40   h  of the developing frame holders  40  and  41 , stabilizing the distance between the photosensitive drum  7  and developing roller  9   c  (preventing the distance from widening). 
     As already described, the long guide  12   a  is disposed on the external surfaces of the developing frame holders  40  and  41 . In addition, the metallic plate toner detecting contact point  122  for detecting the amount of the remaining toner, and the developing bias contact point  121 , are fitted on the developing frame holder  40 ; these contact points  121  and  122  are fixed to the developing frame holder  40  as the dowels provided on the internal surface of the developing frame holder  40  are forced into the locking hole of the contact points. 
     To begin with, how the toner detection contact point  122  is attached will be described with reference to the drawings. 
     FIG. 24 is a sectional view of FIG. 23B, at the (I)—(I) line, and FIG. 25 is an enlarged view of the toner detection contact point illustrated in FIG.  23 B and the adjacencies thereof. The toner detection contact point  122  has an external contact point portion  122   a  and an internal contact portion  122   b . The external contact point portion  122   a  is disposed on the external surface of the holder  40 , and when the process cartridge B is in the apparatus main assembly  14 , it contacts a toner detection contact point member  126  provided on the apparatus main assembly  14 . The internal contact point portion  122   b  presses on the U-shaped portion  9   h   1  of the antenna rod  9   h . Referring to FIG. 24, the external contact point portion  122   a  is at substantially the same level as the side plate  40   a  of developing frame holder  40 . The internal contact point portion  122   b  is disposed within the developing frame holder  40 , opposing the antenna rod  9   h.    
     Referring to FIG. 25, the toner detection contact point  122  is mounted on the developing frame holder  40 , with its locking flap  122   c   1  cut out of the mounting base  122   c  being fitted around the dowel  40   h  which projects inwardly from the side plate  40   a , and the mounting base  122   c  being in contact with the side plate  40   a . Further, from the mounting base  122   c , an angled portion  122   d  is extended at an angle, and from the angled portion  122   d , the internal contact point  122   b  is extended at an angle, so that the internal contact point  122   b  becomes parallel to the side plate  40   a . Further, a connective portion  122   e , which is bent outward at 90 degrees from the mounting base  122   c , projects outward along one of the edges of the first rectangular hole  40   c  formed in the side plate  40   a . Then, the connective portion  122   e  is bent at 90 degrees in the direction opposite to the direction in which the connective portion  122   e  is already bent, constituting the external contact point portion  122   a . The external contact point portion  122   a  is in contact with the bottom surface of a recessed portion  40   i  formed in the side plate  40   a . The depth of this recessed portion  40   i  is substantially the same as the thickness of the external contact point portion  122   a  (FIG.  24 ). Therefore, the outward facing surface of the external contact point portion  122   a , and the outward facing surface  40   a   1  of the side plate  40 , are at substantially the same level. Further, the end portion of the external contact point portion  122   a  is put through the second rectangular hole  40   j  formed in the side plate  40   a , reaching the interior of the side wall  40   a , with an end fixing portion  122   f  being engaged with a dowel  40   k  projecting from one of the walls of the second rectangular hole  40   j . This is the way that toner detection contact point is mounted on the developing frame holder  40 . 
     Referring to FIG. 24, a width L 2  of the first hole  40   c , of the side plate  40   a , is greater than a distance L 1  between the side wall facing surface of the mounting base  122   c  of the toner detection contact point  122  and the outwardly facing surface of the external contact point portion  122   a , and is also greater than the height of the end fixing portion  122   f . Further, a gap large enough to allow the end fixing portion  122   f  of the toner detection contact point  122  to be passed through is provided between the end surface of the dowel  40   k  within the second hole  40   j  and the opposing surface of the second hole. 
     The toner detection contact point  122  is mounted in the following manner. First, the end fixing portion  122   f  is inserted into the first hole  40   c , from the inside of the developing frame holder  40 . Then, the end fixing portion  122   f  is inserted into the second hole  40   j  by rotating the toner detection contact point  122  in the clockwise direction of FIG.  24 . Subsequently, the hole  122   c  of the mounting base  122   c  is engaged with the dowel  40   k . On the other hand, the end fixing portion  122   f  rides over the dowel  40   k  due to its own elasticity, and the hole of the end fixing portion  122   f  engages with the dowel  40   k.    
     The developing bias contact point  121  will be described. 
     The developing bias contact point  121  comprises a plate spring portion  121   a  located within the developing frame holder  40 ; an internal contact point portion  121   b ; and an external contact point portion  121   c  located on the outwardly facing surface  40   a   1 . As the developing frame holder  40  is attached to the developing frame  12 , the plate spring portion  121   a  elastically contacts the bent portion  9   d   1   a  of the metal plate substantially equal to the potential of the developing roller  9   c.  The internal contact point portion  121   b  is fitted around a boss  40 f provided with th aforementioned hole  40 e, being elastically in contact with the coil spring contact point  91  which is fitted around the  40   f  (contact pressure is approx. 100 g to 300 g). The frictional area of the internal contact point portion  121   b  may be coated with electrically conductive grease if desired. The external contact point portion  121   c  is disposed in the recessed portion of the side plate  40   a , and its external surface outwardly facing surface  40   a   1  of the developing frame holder  40 . When the process cartridge B is in the apparatus main assembly  14 , external contact point portion  121   c  is in contact with a developing frame contact point member  125  provided in the apparatus main assembly  14 , and receives the developing bias to be applied from the apparatus main assembly  14  to the developing roller  9   c.  The developing bias received from the apparatus main assembly  14  is applied to the developing roller  9   c  through the developing bias contact point  121  and coil spring contact point  91 . 
     As the developing frame holder  40  is attached to the developing frame  12 , the internal contact point portion  122   b  in the form of a plate spring comes in contact with the U-shaped portion  9   h   1  of the antenna rod  9   h  illustrated in FIG. 28; therefore, the toner detection contact point  122  is electrically connected to the antenna rod  9   h . The contact pressure between the antenna rod  9   h  and internal contact point portion  122   b  is approx. 100 g. When the process cartridge B is in the apparatus main assembly  14 , the external contact point portion  122   a  provided on the outwardly facing surface  40   a   1  of the developing frame holder  40  is electrically connected to the contact point member  126  provided in the apparatus main assembly  14 . Therefore, an electrical signal, correspondent to the capacitance which changes in response to the change in the amount of toner between the developing roller  9   c  and antenna rod  9   h  is transmitted to the developing frame  12  through the antenna rod  9   h , and toner detection contact point  122 . As the control section (not shown) detects that the electric signal transmitted to the contact point member  126  has reached a predetermined value, it signals a need for process cartridge exchange. Three engagement holes  40   g  provided in the internal surface of the developing frame holder  40  are engaged with the corresponding end portions of the dowels  12   e ,  12   f  and  12   g  which serve as the gear shafts for the gears  9   q ,  9   r  and  9 the illustrated in FIG.  35 . In other words, the dowels  12   e ,  12   f  and  12   g  are supported by the developing frame holder  40  and the developing frame  12 , coming between the two. The engagement hole  40   m  provided in the internal surface of the developing frame holder  40 , rotatably supports the stirring gear  9   m.    
     As is evident from the foregoing description, the fact that various functions are assigned to a single component (developing frame holder) leads to improvement in assembling efficiency, and also, cost reduction. 
     Further, according to this embodiment, developing frame holder  40  comprises the rotatable shaft  20 , spring seat  40   b , long guide  12   a,  engagement hole (hole  40   a ) for magnet  9   g , mount (boss  40   f  and the like) for the developing bias contact point  121 , mount (dowel  40   h , first hole  40   c ), developing frame holder  40  (dowel  40   k  and the like) for the toner detection contact point  122 , engagement hole  40   m , pin  40   d , screw hole  401 , and the like, and these portions are integral formed with the developing frame holder  40 . The developing frame holder  41  comprises the rotatable shaft  20 , spring seat  40   b , long guide  12   a,  and the like, and these portions are integrally formed with the developing frame holder  41 . Each of the developing frame holders  40  and  41  is formed, as a single piece component of acrylonitrile-styrene copolymer resin (containing glass filler by 20%) 
     The positions of the developing frame holders  40  and  41  are fixed as the pins  40   d  of the developing frame holders  40  and  40  are inserted into the corresponding holes  12   p  of the developing frame  12 . Then, the developing frame holders  40  and  41  are fixed to the developing frame  12  with the use of screws put through the screw holes  401  (developing frame holders  40  and  41 ), and screw holders  12   r   1  (developing frame  12 ). 
     [Structure of Bottom Surface of Cleaning Frame] 
     The developing frame  12  and cleaning frame  13  are provided with guide ribs  121  and  13   m , which project from the bottom surfaces thereof, respectively, extending in parallel in the moving direction of the recording medium or material  2 . Both guide ribs  121  and  13   m  are arranged in such a manner that the outermost ribs  121  and  13   m  fall within the path of the widest piece of recording medium  2  by a small margin. In this embodiment, the outermost ribs are located approx. 5 mm inwardly from the edges of the path of the widest piece of recording medium  2 . The remainder of the ribs are spread between the outermost ribs to facilitate conveyance of the recording medium  2 . The image forming apparatus in this embodiment is of a type that can accommodate recording medium  2  of different sizes, and the recording medium  2  is centered regardless of size (center line CL coincides with the center line of the recording medium  2 ). Therefore, the arrangement of the ribs provided on the bottom surface of the developing frame  12  and cleaning frame  13  is symmetrical relative to the (center line CL). The rib height is set at predetermined values for the developing frame  12  and cleaning frame  13 , respectively, to facilitate conveyance of the recording medium  2 . By adopting the above structure, the image disturbance due to the contact between the pre-fixation toner image and the bottom survace of the cleaning frame  13  can be prevented, while improving conveyance efficiency. FIG. 34 shows an example of measurement in millimeters between the center line CL and various ribs, along with the symbols correspondent to the standard sizes (Japan Industrial Standard) for the recording medium  2 . For example, a symbol A3L stands for an A3 size recording medium fed in the longitudinal direction; a symbol A4s stands for an A4 size recording medium fed in the widthwise direction. A symbol ENV stands for a recording medium of envelope size, and EXE corresponds to a recording medium of an EXE size. The guide ribs  121  and/or  13   m , located 5.0 mm, 13.0 mm and 28 mm away from the center line CL, are the ribs which make contact with the center line of the recording medium  2 . 
     FIG. 34 is a schematic view of the bottom portion of the cleaning frame  13  as seen from the sheet conveyance direction. This embodiment is different in that the height of guide ribs  13   m  is symmetrically increased in relation to the distance from the center line; both ribs of each rib pair correspondent to one of the various sheet sizes of the recording medium  2  have the same height. This rib arrangement can reliably prevent the ribs located toward the center line CL from coming in contact with the image bearing surface of the recording medium  2 , reliably preventing the image disturbance. The horizontal rib arrangement in this embodiment is the same as the embodiment in which the rib height is the same for all ribs. 
     [Structure of Electrical Contact Points] 
     Hereinafter referring to FIGS. 5,  8 ,  9 A,  9 B,  19 A, and  19 B the connection and placement of the contact points, which establishes electrical connections between the process cartridge B and the laser beam printer main assembly  14  when the former is installed into the latter, will be described. 
     The process cartridge B is provided with a plurality of electrical contact points: (1) Electrically conductive grounding contact point  119  electrically connected to the photosensitive drum  7  to ground the drum  7  through the apparatus main assembly  14 ; (2) Electrically conductive charging bias contact point  120  electrically connected to the charging roller shaft  8   a  in order to apply a charge bias from the apparatus main assembly  14  to the charging roller  8 ; (3) Electrically conductive developing bias contact point  121  electrically connected to the developing roller  9   c  in order to apply a developing bias from the apparatus main assembly  14 ; and (4) Electrically conductive toner remaining detecting contact point  122  electrically connected to an antenna rod  9   h  in order to detect the amount of the remaining toner. All of these four contact points  119 - 122  are exposed on the lateral surface (right-hand side) of the cartridge frame, with intervals large enough to prevent electrical leakage among them. As described before, the ground contact point  119  and charge bias contact point  120  are disposed on the cleaning means frame  13 , and development bias contact  121  and toner remainder detecting contact point  122  are disposed on the development chamber frame  12  (developer holder  40 ). It should be noted here that the toner remaining detecting contact point  122  doubles as a cartridge detecting contact point for detecting the presence (or absence) of the process cartridge within the apparatus main assembly  14 . 
     The grounding contact point  119  is constituted of the electrically conductive axial shaft  7   a  of the photosensitive drum  7 , or an electrically conductive insert molded in the shaft  7  of resin material. In this embodiment, it is constituted of a metallic shaft  7   a  of iron or the like. The other contact points  120 ,  121  and  122  are approximately 0.1 mm to 0.3 mm thick electrically conductive metallic pieces, for example, stainless steel piece, phosphor bronze piece, or the like, which are planted on the surface so as for their leg portions to reach into the process cartridge interior. The charging bias contact point  120  is exposed on the driving side surface (lateral side C 1 ) of the cleaning unit C, and the developing bias contact point  121  and toner remaining detecting contact point  122  are exposed on the driving side surface (lateral side D 1 ) of the developing unit D. 
     More specifically, referring to FIG. 20, in this embodiment, the helical drum gear  7   b  is provided at one end of the photosensitive drum  7  in the axial direction of the drum  7  as described before. This helical drum gear  7   b  engages with the helical driver gear  28  provided on the apparatus main assembly  14  to rotate the drum  7 . As this helical gear  7   b  rotates, it generates a thrust (in the direction of an arrow d in FIG.  20 ), pressing thereby the drum  7 , which is mounted on the cleaning means frame portion  13  with the allowance of some play in its longitudinal direction, toward the direction of the helical gear  7   b . As a result, one  7   b   1  of the lateral surfaces of the helical gear  7   b  remains in contact with the internal surface  13   k   1  of one  13   k  of the lateral surfaces of the cleaning means frame portion  13  of the cartridge frame, whereby the position of the drum  7  within the cartridge B in the axial direction is regulated. The grounding contact point  119  and charging bias contact point  120  are exposed on the one  13   k  of the lateral surfaces of the cleaning means portion  13  of the frame, wherein the grounding contact point  119  is at the end of the drum shaft  7   a , and projects outward slightly (approximately 0.8 mm) beyond the end of the aforementioned cylindrical guide  13   a.  This drum shaft  7   a  is put through the drum cylinder  7   d  (aluminum cylinder in this embodiment) covered with a photosensitive layer  7   e , and is supported at each end by the cylindrical guide  13   a,  which in turn is supported on the lateral walls  13   c  and  13   d . The drum cylinder  7   d  and shaft  7   a  are connected with a grounding plate  7   f , which is in contact with both the internal surface  7   d   1  of the drum cylinder  7   d  and peripheral surface  7   a   1  of the shaft  7   a.    
     The charging bias contact point  120  is located almost directly above the long guide  12 , that is, adjacent to the cleaning means portion  13  of the frame, which supports the charging roller  8  (FIG.  9 A). Also, the charging bias contact point  120  is electrically connected to the charging roller shaft  8   a  through an electrically conductive member  120   a , which is in contact with the charging roller shaft  8   a.    
     Next, the developing bias contact point  121  and toner remaining detecting contact point  122  will be described. These two contact points  121  and  122  are located on one surface, D 1 , of the lateral surface of the developing unit D, that is, the same side as the lateral surface  13   k  of the cleaning means portion  13  of the frame. The developing bias contact point  121  is located directly below the long guide  12   a  and adjacent to the right-hand end of the frame portion  12   c  where the magnet  9   g  contained in the developing roller  9   c  is supported (FIG.  5 ), and is electrically connected to the developing roller  9   c  through the coil spring contact point  91 , which is in contact with the lateral end of the developing roller  9   c  (FIG.  9 B). Referring to FIG. 5, the toner remaining detecting contact point  122  is disposed on the upstream side of the long guide  12   a  relative to the cartridge inserting direction (arrow X direction in FIG.  8 ), and is connected to an antenna rod  9   h , which is disposed on the side of the toner container  11 A and extends in the longitudinal direction of the developing roller  9   c  in parallel with the developing roller  9   c  as shown in FIG. 9B, through the electrically conductive member  9   f , which is in contact with an antenna rod  9   h . The antenna rod  9   h  is disposed so as to hold a predetermined distance from the developing roller  9   c.  The capacitance between this antenna rod  9   h  and developing roller  9   c  varies in response to the amount of the toner present between two components; therefore, the amount of the remaining toner is detected by measuring this capacitance change as a potential difference change, through a control section (unillustrated) in the apparatus main assembly  14 . 
     Here, the terminology “amount of the remaining toner” means an amount of the toner that creates a predetermined amount of capacitance by being present between the developing roller  9   c  and antenna rod  9   h . In other words, the detection of the predetermined amount of capacitance means that the amount of the toner remaining in the toner chamber  11 A has reached the predetermined amount. 
     Thus, it is detected by the control section, which is provided in the apparatus main assembly  14  and is connected to the cartridge B through the toner remaining detecting contact point  122 , that the capacitance has reached a predetermined first value; whereby it is determined that the amount of the toner remaining in the toner chamber  11   a  has reached the predetermined amount. When it is detected that the capacitance has reached the aforementioned first determined value, the apparatus main assembly  14  signals the need for process cartridge B exchange (for example, flashing light, buzzing sound). When the capacitance detected by the control section matches a predetermined second value, which is smaller than the first value, the detecting circuit determines that the cartridge B has been installed in the apparatus main assembly  14 . The control section circuit does not allow the apparatus main assembly  14  to be driven unless it detects that the cartridge B has been installed in the apparatus main assembly. In other words, the control section does not allow the apparatus main assembly  14  to start forming images. 
     It may be arranged so that a warning signal (for example, blinking light or the like) may be provided to inform the operator of the absence of the cartridge B in the apparatus. 
     Next, a description will be given as to the connection between the contact point provided on the cartridge B and the contact point member provided on the apparatus main assembly  14 . 
     Referring to FIGS. 19A and 19B, four contact point members, which make contact with corresponding contact points  119 - 122  when the process cartridge is installed in the apparatus A, are provided on one of the lateral walls of the cartridge accommodating space S of the image forming apparatus A (grounding contact point member  123  which electrically contacts the grounding contact point  119 , charging bias contact point member  124  which electrically contacts the charging bias contact point  120 , developing contact point member  125  which electrically contacts the developing bias contact point  121 , and toner detection contact point member  126  which electrically contacts the toner remaining detecting contact point  122 ). 
     As shown in FIGS. 19A and 19B, the grounding contact point member  123  is disposed in correspondence to the groove  16   a   5 . The developing bias contact point member  125  and toner remaining detecting contact point member  126  are disposed below the first guide portion  16   a . The charging bias contact point member  124  is disposed above the second guide portion  16   b.    
     Here, the positional relationship between the contact points and guides will be described. 
     First, referring to FIG. 5, as for the positional relationship in the vertical direction (as seen from the horizontal direction), the developing bias contact point  121  is the bottommost one; the toner remaining detecting contact point  122 , long guide  12   a  and cylindrical guide  13   a  (grounding contact point  119 ) are disposed above the bias contact point  121 , being at about the same level; above them is the short guide  13   b,  and the topmost one is the charging bias contact point  120 . As for the positional relationship in the cartridge inserting direction (arrow X direction), the toner remaining detecting contact point  122  is the most upstream one; next is the long guide  12   a;  at a further downstream location is the charging bias contact point  120  and developing bias contact point  121 ; and at the most downstream locations are short guide  13   b  and cylindrical guide  13   a  (grounding contact point  119 ). Arranging the contact points as described above allows the charging bias contact point  120  to be positioned near the charging roller  8 ; the developing bias contact point  121 , near the developing roller  9   c;  the toner remaining detecting contact point  122 , near the antenna rod  9   h ; and the grounding contact point  119  to be positioned near the photosensitive drum  7 . Therefore, the wiring for the contact points can be shortened. 
     The measurements of the contact points are as follows: the charging bias contact point  120  is approximately 10.0 mm in height and width (tolerable range of 8.0 mm to 12.0 mm); developing bias contact point  121 , approximately 9.0 mm in height (tolerable range of 6.0 mm to 12.0 mm) and approximately 8.0 mm (tolerable range of 5.0 mm to 11.0 mm); toner remaining detecting contact point  122 , approximately 8.0 mm (tolerable range of 6.0 mm to 10.0 mm) in height and approximately 9.0 mm (tolerable range of 7.0 mm to 11.0 mm) in width; and grounding contact point  119  is circular and its diameter is approximately 7.0 mm. The charging bias contact point  120 , developing bias contact point  121 , and toner remaining detecting contact point  122  are rectangular. 
     The grounding contact point member  123  is an electrically conductive plate spring member, and is mounted in the groove  16   a   5 , in which the cylindrical guide  13   a  (in which the drum shaft  7   a  of the photosensitive drum  7  is fitted), on which the grounding contact point  119  of the cartridge B is mounted, is disposed to fix the position of the cartridge B, whereby the grounding contact point member  123  is grounded through the chassis of the apparatus main assembly (FIGS. 19A,  19 B, and  26 ). The other contact point members  124 ,  125  and  126  are mounted in the corresponding holder covers  127  in such a manner as to be projected therefrom by the corresponding compression springs  129 . This arrangement will be described referring to the charging bias contact point member  124 . Referring to FIG. 20, the charging bias contact point member  124  is placed under a holder cover so that it projects but does not come off, and then, this holder cover  127  is fixed to a circuit board  128  mounted on one of the lateral walls of the apparatus main assembly, whereby the contact point members are electrically connected to the wiring patterns by the electrically conductive compression springs  129 , correspondingly. 
     Next, referring to FIGS. 21A through 21C, it will be described with reference to the charging bias contact point member  120  how the contact points on the cartridge side come in contact with the corresponding contact point members on the image forming apparatus side when the process cartridge B is installed into the image forming apparatus A. FIGS. 21A through 21C are explanatory drawings, which depict the state of the process cartridge B in the image forming apparatus A, wherein an arrow mark H designates the movement of the charging bias contact point  124  on the apparatus main assembly, relative to the process cartridge B, when the cartridge B is installed into the image forming apparatus A. It should be noted here that FIGS. 21A through 21C are a cross-section of FIG. 5 at a line O. 
     During the installation of the process cartridge B into the image forming apparatus A using the guide members  16   a  and  16   b  as the guide, the charging bias contact point member  124  is in the state depicted in FIG. 21A before it reaches the predetermined position where it is to be fixedly disposed. At this time, the charging bias contact point member  124  is not in contact with the flat surface  20  of the cleaning means portion  13  of the frame. As the cartridge B is further inserted, the charging bias contact point member  124  is advanced to a position in FIG.  21 B. In this state, it remains in contact with the slanted surface  31  (FIG. 5) formed on the right lateral wall  13   c  of the cleaning means portion  13  of the frame; slides on this slanted surface  31 , whereby it is gradually pressed, compressing thereby gradually the compression spring  129 ; and smoothly moves onto the flat surface  32  where the charging bias contact point  120  is exposed. When the inserted cartridge B arrives at the predetermined location, the contact member  124  arrives at a position in FIG. 21C where it makes contact with the charging bias contact point  120 . The other contact point members  125  and  126  come in contact with the contact points  121  and  122 , respectively, in the same manner. 
     With such an arrangement as described above being in place, when the cartridge B is guided by the guide member  16  into the predetermined cartridge accommodating location, the contact points and the corresponding contact point members are reliably placed in contact with each other. 
     Further, when the process cartridge B is positioned at the predetermined location in the apparatus main assembly  14 , the grounding contact point member  123  in the form of a plate spring makes contact with the grounding contact point  119  projecting from the cylindrical guide  13   a  (FIG.  20 ). As the process cartridge B is inserted into the apparatus main assembly  14 , the grounding contact point  119  and grounding contact member  123  electrically contact with each other, grounding thereby the photosensitive drum  7 . The charging bias contact point  120  and charging bias contact member  124  electrically contact with each other, allowing thereby a high voltage (superposed voltage of AC and DC voltages) to be applied to the charging roller  8 . The developing bias contact point  121  and developing contact member  125  make electrical contact with each other, allowing thereby a high voltage to be applied to the developing roller  9   c.  The toner remaining detecting contact point  122  and toner remaining detecting contact member  126  make electrical contact with each other, allowing thereby information reflecting the capacitance to be transmitted to the apparatus main assembly  14 . 
     Next, a case in which the photosensitive dram  7  is rotated by driving the image forming apparatus A, will be described. The photosensitive drum  7  is given an approximately 2 mm to 3 mm thrust play in the axial direction so that it is easier to install the process cartridge B into the image forming apparatus A. Therefore, it is necessary for the charging bias contact point member  124  or the like to be capable of projecting by a distance larger than the thrust play. Further, in this embodiment, a plate spring  45  is provided, which presses the process cartridge B toward one side (side where the contact point members  123 - 126  are located) of the apparatus main assembly when the cartridge B is in the apparatus main assembly. This plate spring  45  is on the side opposite to the side where the contact point members are located, above the first installation guide  16   a.    
     Further, when the contact points  119 - 122  of the process cartridge B are disposed, as they are in this embodiment, on the side where the helical drum gear  7   b  is disposed (lateral wall on the driving side), the connection for mechanically driving the cartridge B by the apparatus main assembly through the helical drum gear  7   b , and the electrical connection between the cartridge B and apparatus main assembly through the contact points  119 - 122 , can be made on the same side of the cartridge B. Therefore, when the aforementioned side of the cartridge B is used as the referential side, the integrated error in the component sizes can be reduced, which makes it possible to mount more accurately the contact points and helical gear. Further, when a helical drum gear with teeth cut in such a direction as to generate a thrust directed toward the side where the helical drum gear is positioned is used, the position of the photosensitive drum  7  in the axial direction is fixed on the side where the contact points are located; therefore, in this case, the accuracy in the positional relationship between the photosensitive drum  7  and the contact points is also improved, in addition to the aforementioned effects. Further, when a lever  23  (FIG. 6) for opening or closing the drum shutter  18  is located, as it is in the aforementioned embodiment, on the side opposite to the one where the contact points  119 - 122  are located, the frictional resistance generated on one side of the cartridge by the contact points  119 - 122  as the cartridge B is inserted into the image forming apparatus A, and the resistance (or pressure), which is made by the lever  23  (FIG. 6) for opening or closing the drum shutter member  18 , are distributed toward the longitudinal ends of the cartridge B when the process cartridge B is inserted into the image forming apparatus A; in other words, the resistance generated when the cartridge B is inserted is evenly distributed in the longitudinal direction of the cartridge B. Therefore, the cartridge B can be smoothly inserted. 
     Further, as described in the preceding embodiment, when all the contact points of the process cartridge B are positioned on one and the same lateral wall of the cartridge frame, and the process cartridge B is placed under the elastic pressure generated by the plate spring, it is possible to provide stable electrical connections between the contact points and the corresponding contact point members on the apparatus main assembly side. 
     FIG. 22 illustrates an arrangement in which the contact points are located on the side where the aforementioned lever  23  is located. This arrangement can also sufficiently provide the aforementioned effects. 
     Further, in each of the preceding embodiments, the process cartridge B is of a type which is used to form a monochrome image, but the present invention is also applicable to a multicolor process cartridge, which comprises two or more developing means and is used to form a multicolor image (image of two colors, three colors, or full-color). 
     As for the electrophotographic photosensitive member, it is not limited to the aforementioned photosensitive drum  7 . The present invention is also applicable to the following. To begin with, the photoconductive material is usable as the photosensitive material. As for the photoconductive material, amorphous silicon, amorphous selenium, zinc oxide, titanium oxide, organic photoconductor (OPC), or the like, is usable. Further, as for the configuration of a base member on which the photosensitive material is placed, a base member in the form of a drum or a belt is used. For example, in the case of the base member of the drum type, the photoconductive material is coated, deposited, or placed by the like means on a cylinder of aluminum alloy or the like. 
     As for the developing method, the present invention is compatible with various well-known methods such as the double component magnetic brush developing method, cascade developing method, touch down developing method, cloud developing method, and the like. 
     Further, as to the structure of the charging means, the so-called contact charging method is employed in the first embodiment, but it is needless to say that the present invention is also applicable to other conventional charging methods such as the one in which a metallic shield of aluminum or the like is placed on three sides of a tungsten wire, and positive or negative ions generated by applying a high voltage to the tungsten wire are transferred onto the surface of the photosensitive drum to charge it uniformly. 
     Further, the aforementioned charging means may be of the blade type, (charging blade), pad type, block type, rod type, wire type, or the like, in addition to the roller type described previously. 
     As for the method for cleaning the residual toner on the photosensitive drum, the cleaning means may be constituted of a blade, fur brush, magnetic brush, or the like. 
     As described above, all of the plural electrical contact points of the process cartridge are disposed on only one of the lateral surfaces of the cartridge frame; therefore, the electrical connection between the process cartridge and image forming apparatus can be reliably established by positioning the process cartridge in such a manner as to be pressed by elastic means toward its lateral surface where the electrical contact points are disposed. 
     Further, the electrical connection, as well as the driving mechanism connection, between the process cartridge and image forming apparatus can be more reliably established by means of disposing the helical gear and electrical contact points on the side toward which the electrophotographic photosensitive member is pressed by the rotation of the helical gear for transmitting the driving force to the photosensitive member. 
     Further, the distance the wiring must be routed within the process cartridge can be shortened by means of disposing each of the contact points in the same manner as described in the preceding embodiments. 
     Further, according to the embodiment, the electrical circuit board of the apparatus main assembly, to which the aforementioned electrical contact points are to be connected, can be vertically arranged on the lateral surface of the apparatus main assembly; therefore, the apparatus size can be reduced. 
     As described in the foregoing, according to the embodiment, the toner supply performance is high even if the amount of toner is large. 
     According to the present invention, there is provided a developing device frame, a process cartridge and an electrophotographic image forming apparatus, which are easy to assemble. 
     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 with in the purposes of the improvements or the scope of the following claims.