Patent Publication Number: US-9897970-B2

Title: Developer container, developing device, process cartridge and image forming apparatus

Description:
FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to a developer container, a developing device, a process cartridge and an image forming apparatus. 
     Here, the developer container is a container for accommodating a developer carrying member, for visualizing an electrostatic latent image with the developer. Further, the developer container is used alone so as to be detachably mountable to the image forming apparatus. 
     Further, the process cartridge refers to a cartridge constituted by integrally assembling at least the developer container and the developer carrying member into a unit, which is detachably mountable to an image forming apparatus main assembly. 
     Examples of the image forming apparatus may include an electrophotographic copying machine, an electrophotographic printer (such as an LED printer or a laser beam printer) and an electrophotographic facsimile machine, in which an image is formed on a recording material (medium) by using an electrophotographic image forming process. 
     In the image forming apparatus using the electrophotographic image forming process, a process cartridge type in which an electrophotographic photosensitive drum and a process means actable on the drum into a cartridge (unit), which is detachably mountable to the image forming apparatus main assembly is employed. According to this process cartridge type, maintenance of the apparatus can be performed by a user himself (herself) without relying on a service person, and therefore operativity was able to be considerably improved. For that reason, this process cartridge type has widely been used in the image forming apparatuses. 
     Such a process cartridge includes a developer accommodating portion for accommodating a toner as the developer for visualizing a latent image formed on the photosensitive drum and a developing unit including a developing means for developing the latent image with the toner. During a brand-new state of the process cartridge including the developing unit, a toner sealing member for preventing the developer in the developer accommodating portion from entering a developing unit side through an opening provided in the developer accommodating portion is provided. For that reason, when the user uses the process cartridge, the user peels off the toner sealing member from the process cartridge and then mounts the process cartridge in the image forming apparatus main assembly. 
     Further, in recent years, from the viewpoint of usability, a constitution in which the toner sealing member is peeled off only by mounting the process cartridge into the image forming apparatus main assembly is disclosed (Japanese Laid-Open Patent Application (JP-A) Hei 5-197288 and JP-A 2014-66967). In this constitution, one end portion of the toner sealing member is mounted on a rotatable member in the developer accommodating portion and the toner sealing member is automatically wound up around the rotatable member with drive of the image forming apparatus main assembly, so that the toner can be sent to the developing unit. 
     However, in the constitution in which the toner sealing member provided on the opening of the toner accommodating portion is pulled by rotational drive of the image forming apparatus main assembly, there was a problem that a torque when the toner sealing member was pulled was large. This is because when the toner sealing member is pulled, a force for peeling off a welded portion between the developer accommodating portion and the toner sealing member is needed. The welded portion is portion where an adhesive layer is provided on the toner sealing member and then heated and welted at the opening of the developer accommodating portion and thus is bonded to a periphery of the opening, so that the opening is completely closed (blocked) using the welded portion and thus toner leakage is prevented. However, from the viewpoints of energy saving and downsizing in recent years, there arose a need to reduce the torque, when the toner sealing member was pulled, to the possible extent. 
     SUMMARY OF THE INVENTION 
     A principal object of the present invention is to reduce a torque when a toner sealing member is pulled while preventing toner leakage from a developer accommodating portion before a user uses an image forming apparatus. 
     According to an aspect of the present invention, there is provided a developer container comprising: a frame, provided with an opening, for accommodating a developer; a sealing member, including a folded-back portion, for sealing the opening; and a sandwiching portion for sandwiching the folded-back portion of the sealing member, wherein in a plane perpendicular to the opening, the sealing member is nonwelded in the sandwiching portion. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In  FIG. 1 , (a) and (b) are sectional views of a developing device unit according to Embodiment 1. 
         FIG. 2  is a sectional view of an image forming apparatus in Embodiment 1. 
         FIG. 3  is a sectional view of a cartridge in Embodiment 1. 
         FIG. 4  is a perspective view showing a state in which the cartridge is being mounted into the image forming apparatus in Embodiment 1. 
         FIG. 5  is a perspective view of the cartridge in Embodiment 1. 
       In  FIG. 6 , (a) and (b) are perspective views each showing a stirring member in Embodiment 1. 
       In  FIG. 7 , (a) and (b) are perspective views for illustrating assembling of a sealing member in Embodiment 1. 
       In  FIG. 8 , (a) to (d) are sectional views for illustrating an unsealing operation of the sealing member in Embodiment 1. 
       In  FIG. 9 , (a) and (b) are illustrations each showing a toner filling port in the developing device unit in Embodiment 1. 
       In  FIG. 10 , (a) is an illustration of a toner supply opening in Embodiment 1, and (b) is a graph showing a result of comparison and investigation of a torque during unsealing of a sealing member in Embodiment 1 and Comparison Example. 
       In  FIG. 11 , (a) and (b) are sectional views of a developing device unit according to Embodiment 2. 
       In  FIG. 12 , (a) and (b) are schematic views for illustrating a sandwiching portion in Embodiment 2. 
         FIG. 13  is a graph showing a result of comparison and investigation of a torque during unsealing of a sealing member in Embodiment 2 and Comparison Example. 
       In  FIG. 14 , (a) to (c) are sectional views of a developing device unit according to Embodiment 3. 
         FIG. 15  is a graph showing a result of comparison and investigation of a torque during unsealing of a sealing member in Embodiment 3 and Comparison Example. 
       In  FIG. 16 , (a) to (c) are sectional views of another developing device unit in Embodiment 3. 
       In  FIG. 17 , (a) and (b) are sectional views of a developing device unit according to Embodiment 4. 
         FIG. 18  is a graph showing a result of comparison and investigation of a torque during unsealing of a sealing member in Embodiment 4 and Comparison Examples 1 and 2. 
       In  FIG. 19 , (a) and (b) are sectional views of a developing device unit according to Embodiment 5. 
         FIG. 20  is a graph showing a result of comparison and investigation of a torque during unsealing of a sealing member in Embodiment 5 and Comparison Examples 1 and 2. 
       In  FIG. 21 , (a) and (b) are sectional views of a developing device unit according to Embodiment 6. 
         FIG. 22  is a graph showing a result of comparison and investigation of a torque during unsealing of a sealing member in Embodiment 6 and Comparison Examples 1 and 2. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiments for carrying out the present invention will be specifically described with reference to the drawings. Dimensions, materials, shapes and relative arrangement of constituent elements described in the following embodiment should be appropriately be changed depending on structures and various conditions of devices (apparatuses) to which the present invention is applied. Accordingly, the scope of the present invention is not intended to be limited to the following embodiments. 
     [Embodiment 1] 
     An image forming apparatus to which a cartridge according to this embodiment is detachably mountable will be described. In this embodiment, as the image forming apparatus, a laser beam printer using electrophotography will be described as an example. 
     (Structure of Image Forming Apparatus) 
     In  FIG. 2 , the image forming apparatus in this embodiment is the laser beam printer, using the electrophotography, in which a cartridge B is detachably mountable to an apparatus main assembly A. When the cartridge B is mounted in the apparatus main assembly A, above the cartridge B, an exposure device  3  (laser scanner unit) is provided. Further, below the cartridge B, a sheet tray  4  in which a recording material (sheet material P) to be subjected to image formation is accommodated is provided. 
     Further, in the apparatus main assembly A, along a feeding direction D of the sheet material P, a pick-up roller  5   a , a feeding roller pair  5   b , conveying roller pairs  5   c , a transfer guide  6 , a transfer roller  7 , a conveying guide  8 , a fixing device  9 , a discharging roller pair  10 , a discharge tray  11  and the like are successively provided. Incidentally, the fixing device  9  is constituted by a heating roller  9   a  and a pressing roller  9   b.    
     (Image Forming Process Operation) 
     Next, the image forming process will be described using  FIGS. 2 and 3 . On the basis of a print start signal, an electrophotographic photosensitive drum  62  is rotationally driven at a predetermined peripheral speed (process speed: 215 mm/sec) in an arrow R direction in  FIG. 2 . A charging roller  66  to which a charging bias voltage is applied contacts an outer peripheral surface of the drum  62  and electrically charges the outer peripheral surface of the drum  62  uniformly. The exposure device  3  outputs laser light L depending on image information. The laser light L passes through an exposure window portion  74  provided at an upper surface of the cartridge B, so that the outer peripheral surface of the drum  62  is subjected to scanning exposure. As a result, on the outer peripheral surface of the drum  62 , an electrostatic latent image depending on the image information is formed. 
     On the other hand, as shown in a sectional view of the cartridge in  FIG. 3 , in a developing device unit  20  as a developing device, a toner T in a toner chamber  29  is stirred and fed by rotation of a rotatable member  45 , so that the toner T is sent to a toner supplying chamber  28 . The toner T is carried by a magnetic force of a magnet roller  34  (fixed magnet) on a surface of a developing roller (developer carrying member)  32 . The toner T is regulated in layer thickness on the peripheral surface of the developing roller  32  by a developing blade  42  while being triboelectrically charged. The toner T is transferred onto the drum  62  depending on the electrostatic latent image, so that the electrostatic latent image is visualized as a toner image which is a developer image. 
     Further, as shown in  FIG. 2 , in synchronism with output timing of the laser light L, by the pick-up roller  5   a , the feeding roller pair  5   b  and the conveying roller pair  5   c , the sheet material P accommodated at a lower portion of the apparatus main assembly A is fed from the sheet tray  4 . The sheet material P is supplied to a transfer position between the drum  62  and the transfer roller  7  via the transfer guide  6 . In this transfer position, the toner image is successively transferred from the drum  62  onto the sheet material P. The sheet material P on which the toner image is transferred is separated from the drum  62  and then is conveyed to the fixing device  9  along the conveying guide  8 . Then, the sheet material P passes through a fixing nip between the heating roller  9   a  and the pressing roller  9   b  which constitute the fixing device  9 . At this fixing nip, pressure and heat fixing is effected, so that the toner image is fixed on the sheet material P. The sheet material P on which the toner image is fixed is conveyed to the discharging roller pair  10  and then is discharged onto the discharge tray  11 . 
     On the other hand, as shown in  FIG. 3 , the drum  62  after the transfer is, after a residual toner on the outer peripheral surface of the drum  62  is removed by a cleaning blade  77 , used again in the image forming process. The residual toner removed from the drum  62  is stored in a residual toner chamber  71   b  of a cleaning unit  60 . 
     (Mounting and Demounting Constitution of Cartridge) 
     Next, mounting and demounting of the cartridge B relative to the apparatus main assembly A will be described using  FIG. 4 .  FIG. 4  is a perspective view of the apparatus main assembly in which an openable door  13  is opened for mounting and demounting the cartridge B, and of the cartridge B. 
     The apparatus main assembly is provided with the openable door  13  so as to be rotatable. When the openable door  13  is opened, a guide rail  12  is in sight, and the cartridge B is mounted into the apparatus main assembly A along the guide rail  12 . Then, a driving shaft  14  driven by a motor (not shown) of the apparatus main assembly A engages with a driving force receiving portion provided on the cartridge B. As a result, the drum  62  connecting with the driving force receiving portion receives the driving force from the apparatus main assembly A, and thus is rotated. 
     (General Structure of Process Cartridge) 
     Next, with reference to  FIGS. 3 and 5 , a general structure of the cartridge B will be described.  FIG. 5  is a perspective view for illustrating a structure of the cartridge B. 
     The cartridge B is constituted by combining the cleaning unit  60  and the developing device unit  20 . The cleaning unit  60  is constituted by a cleaning frame  71 , the drum (first bearing member)  62 , the charging roller  66 , the cleaning blade  77  and the like. On the other hand, the developing device unit  20  is constituted by, a cap member  22 , a toner accommodating frame  23 , first and second side members  26 L and  26 R, a developing blade  42 , the developing roller  32 , the magnet roller  34 , a toner stirring sheet  44 , the toner T, an urging member  46 , and the like. These cleaning unit  60  and developing device unit  20  are rotationally movably connected with each other by a connecting member  75 , so that the cartridge B is constituted. 
     Specifically, at free end portions of arm portions  26 aL,  26 aR formed on the first and second side members  26 L,  26 R provided at both end portions of the developing device unit  20  with respect to a longitudinal direction of the developing device unit  20 , rotational movement holes  26 bL,  26 bR in parallel with the developing roller  32  are provided, respectively. Further, at each of longitudinal end portions of the cleaning frame  71 , an engaging hole  71   a  for permitting engagement therein of the connecting member  75  is formed. 
     Then, the arm portions  26 aL and  26 aR are aligned with predetermined positions of the cleaning frame  71 , and then the connecting members  75  are inserted into the rotational movement holes  26 bL and  26 bR and the engaging holes  71   a . As a result, the cleaning unit  60  and the developing device unit  20  are connected with each other rotatably about the connecting members  75 . 
     At this time, urging members  46  mounted at base portions of the arm portions  26 aL and  26 aR abut against the cleaning frame  71 , so that the urging members  46  urge the developing device unit  20  toward the cleaning unit  60  with the connecting members  75  as the rotation centers. As a result, the developing roller  32  is pressed toward the drum  62  with reliability. 
     (Developing Device Unit) 
     Next, the developing device unit in the present invention will be described. First, using  FIG. 6 , a constitution of a rotatable member unit  54  used in the present invention will be described. 
     As shown in  8   a ) of  FIG. 6 , the rotatable member unit  54  is constituted by a sealing member (toner sealing member)  52 , the toner stirring sheet  44  and the rotatable member  45 . The sealing member  52  is constituted by a material compatible with a material of the toner accommodating frame  23  or by a material including an adhesive layer. In this embodiment, as the material of the sealing member  52 , a material, such as PET, PC or PPS, which has flexibility and which includes the adhesive layer capable of being melted by heat and bonded to a frame (container)  23 . The sealing member  52  is provided with a plurality of holes  52   a  arranged in a longitudinal direction, of the rotatable member  45 , which is an axial direction of the rotatable member  45 . 
     The toner storing sheet  44  as a stirring member is formed with a sheet-shaped material, such as PET, PC or PPS, having flexibility, and is provided with a plurality of holes  44   a  arranged in the longitudinal direction of the rotatable member  45  similarly as in the case of the sealing member  52 . 
     The rotatable member  45  used in this embodiment is constituted by an arcuate portion  45   b  and a rectilinear portion  45   c  in cross section as seen in the longitudinal direction of the rotatable member  45 , and a mounting surface  45   d  corresponding to the rectilinear portion  45   c  of the cross section is provided with a plurality of projections  45   a , arranged in the longitudinal direction, for supporting the above-described pluralities of the holes  53   a  and the holes  44   a.    
     The sealing member  52  and the toner stirring sheet  44  are, as shown in (a) of  FIG. 6 , supported at the holes  52   a  and the holes  44   a  by the projections  45   a  of the rotatable member  45 , and thereafter are fixed to the rotatable member  45  by thermal caulking as shown in (b) of  FIG. 6 . In this embodiment, the fixing of the sealing member  52  and the toner stirring sheet  44  is performed by the thermal caulking as described above, the fixing is not limited thereto but may also be performed by another means such as a double-side tape or snap fitting. Further, as regards the mounting surface for the sealing member  52  and the toner stirring sheet  44 , the sealing member  52  and the toner stirring sheet  44  may be mounted on the same mounting surface  45   d  as in this embodiment or may also be mounted on different surfaces of the rotatable member  45 . 
     (Mounting Method of Rotatable Member Unit  54  and Sealing Member  52 ) 
     Next, a mounting method of the rotatable member unit  54  and the sealing member  52  to the toner accommodating frame  23  will be described using  FIG. 7 . In (a) of  FIG. 7 , an arrow X direction is the longitudinal direction which is the axial direction of the rotatable member  45 , and an arrow Z direction is a widthwise (short) direction perpendicular to the axial direction. 
     As shown in (a) of  FIG. 7 , one end portion  52   b  of the sealing member  52  fixed to the rotatable member  45  with respect to the widthwise direction is fixed by the thermal welding or the like or a fixing portion  23   b  (hatched portion in (a) of  FIG. 7 ) provided at a periphery of a toner supply opening  23   a  of the toner accommodating frame  23 . The fixing portion  23   a  is constituted by a first fixing portion  23   c  extending along the longitudinal direction of the toner supply opening  23   a  and by second and third fixing portions  23   d  and  23   e  each extending along the widthwise direction of the toner supply opening  23   a . The second fixing portion  23   d  is positioned on a non-driving side opposite with respect to the longitudinal direction, from a side where the driving shaft  14  is provided in the apparatus main assembly A. The third fixing portion  23   e  is positioned on a driving side which is the same side, with respect to the longitudinal direction, as the side where the driving shaft  14  is provided in the apparatus main assembly A. Further, the sealing member  52  is provided with a folded-back portion U where the sealing member  52  is folded back. 
     As shown in (b) of  FIG. 7 , the toner supply opening  23   a  is sealed (covered) with the sealing member  52  at the fixing portion  23   b . Thereafter, the rotatable member unit  54  is supported by a shaft portion  35   a  of a stirring gear member  35  through a hole  37  provided in the toner accommodating frame  23  by inserting a driving-side end portion  45   f  of the rotatable member  45  into the hole  37 . On the other hand, a shaft portion  45   e  as a non-driving-side end portion of the rotatable member  45  is rotatably supported by an unshown hole provided in the toner accommodating frame  23 . 
     On the driving side, a seal member  36  is provided and constituted so as to prevent toner leakage through the hole  37  of the toner accommodating frame  23 . The rotatable member unit  54  is supported by the toner accommodating frame  23  and thereafter, the cap member  22  is fixed to the toner accommodating frame  23  by welding or the like. 
     (Sandwiching Portion M) 
     In  FIG. 1 , (a) and (b) are sectional views of the developing device unit  20  in this embodiment, in which (a) is the sectional view of an entirety of the developing device unit  20  and (b) is an enlarged view showing the folded-back portion U of the sealing member  52  and a sandwiching portion M in the developing device unit. Cross sections shown in (a) and (b) of  FIG. 1  are planes perpendicular to the toner supply opening  23   a.    
     In this embodiment, as shown in (a) of  FIG. 1 , one end portion  52   b  of the sealing member  52  is welded to the fixing portion  23   c  which is a portion on an upper end of the toner supply opening  23   a . Further, at the sandwiching portion M which is a portion under a lower end of the toner supply opening  23   a , the sealing member is sandwiched in a state in which the sealing member is folded back with the folded-back portion U as a bottom thereof. The sandwiching portion M is constituted by a wall  23   g , provided with the toner supply opening  23   a , constituting the toner accommodating frame  23  and a part  23   h , opposing the wall  23   g , of the toner accommodating frame  23 . A portion, of the sealing member  52 , sandwiched by the sandwiching portion M is not welded (i.e., nonwelded) in the sandwiching portion M when the sealing member  52  is seen on a plane perpendicular to the toner supply opening  23   a . Further, when the folded-back portion U of the sealing member  52  is sandwiched by the sandwiching portion M, a depth of the sealing member  52  (the folded-back portion U) is D, a width of the sealing member M is W, and a thickness of the sealing member  52  is L ((b) of  FIG. 1 ). As a condition of the width W at this time, when the width W is narrowed to the extent that the sealing member  52  is compressed (deformed), the sealing member  52  is not disconnected from the sandwiching portion M. For that reason, as a condition that the folded-back sealing member  52  is not compressed, there is a need to satisfy 2L&gt;W. Further, in the case where the width W is large, it is natural that the sealing member  52  is not in a state in which the folded-back portion U is sandwiched in the sandwiching portion M, and therefore as a result of investigation, it was found that W&lt;5L is desirable. From the above result, as the condition of the width W, it is desirable that 2L&lt;W&lt;5L is satisfied. In this embodiment, the depth D was 10 mm, the width W was 400 μm and the thickness L was 100 μm. By sandwiching the sealing member  52  in the sandwiching portion M in a state in which the sealing member  52  is folded back in the sandwiching portion M with the folded-back portion U as the bottom thereof, the toner T is prevented from leaking out of the toner accommodating frame  23 . 
     In a conventional constitution, the toner leakage was prevented by bonding the sealing member to the frame by welding, but in this case, a load of a torque when the sealing member is peeled off from the frame is large. In order to reduce the load, the sealing member is sandwiched, so that not only the load of the torque is reduced but also a degree of the toner leakage is reduced. That is, the sandwiching of the sealing member (folded-back portion U) is as if a temporally sealing. 
     For that reason, in this embodiment, the sealing member and the frame are not welded to each other in a region of the depth D of the sandwiching portion M in (b) of  FIG. 1 , and in addition, the sealing member is not welded to also a frame portion DU which is on the depth D region and under the opening. That is, a lower portion, of the sealing member, under the opening (on an upstream side with respect to an unsealing direction) is subjected to the temporary sealing for the sandwiching without being weld. 
     However, the present invention is not limited thereto, but the frame portion DU under the opening and the sealing member may also be welded to each other. In this case, compared with conventional welding, a torque load in the above welding is small. That is, the temporary sealing and the welding are used in combination. 
     (Unsealing Method of Sealing Member  52 ) 
     An unsealing operation of the sealing member  52  will be described using (a) to (d) of  FIG. 8 . When the cartridge B is mounted in the apparatus main assembly A and the openable door  13  of the apparatus main assembly A is closed, rotational drive of the apparatus main assembly A is started. With the rotational drive of the apparatus main assembly A, the drum  62  of the cartridge B receives a driving force from the apparatus main assembly A and is rotated. When the drum  62  is rotationally driven, the rotatable member  45  is started to be rotated in an arrow S direction in (a) of  FIG. 8  by a driving gear (not shown) provided in the cartridge B. 
     With rotation of the rotatable member  45 , the sealing member  52  mounted to the rotatable member unit  54  is subjected to tension and receives a force in a direction of being spaced from the toner supply opening  23   a , and therefore the folded-back portion U of the sealing member  52  is disconnected (eliminated) from the sandwiching portion M ((b) of  FIG. 8 ). As a result, the sealing member  52  is peeled off from the toner supply opening  23   a , and therefore the toner T is sent from the toner accommodating frame  23  in a direction toward a developing sleeve by the rotatable member unit  54  ((c) of  FIG. 8 ). Thereafter, with further rotation of the rotatable member unit  54 , the sealing member  52  is peeled off from the fixing portion  23   c  above the toner supply opening  23   a . The toner stirring sheet  44  is mounted at one end portion thereof together with the sealing member  52  on the rotatable member  45 , and therefore by the rotation of the rotatable member  45 , the toner stirring sheet  44  is rotated simultaneously with the sealing member  52 . By this toner stirring member rotated simultaneously with the sealing member  52 , the toner T in the toner chamber  29  is fed while being stirred, and is sent toward the toner supplying chamber  28  through the toner supply opening  23   a . Then, finally, the toner T is coated on the developing sleeve, and the image forming apparatus is in a printable state, so that the drive of the apparatus main assembly A stops ((d) of  FIG. 8 ). 
     (Toner Filling Port and Filling Method) 
     At the sandwiching portion M, different from the welding, the sealing member  52  is not completely fixed, and therefore the sealing member  52  is required to be prevented from disconnecting from the sandwiching portion M particularly during filling of the toner. For that reason, in the case where the toner is filled, there is a need that the toner T is sent to above the sealing member  52  and using a self-weight of the toner T, the sealing member  52  is not readily disconnected from the sealing member M. For that reason, as a filling port C through which the toner T is filled into the developing device unit  20 , the filling port C may desirably be a hatched region shown in (a) of  FIG. 9 . Specifically, as the filling port C, it is desirable that the filling port C is provided in a container wall of the toner accommodating frame  23  on not only a side closer to the toner supply opening  23   a  than an axial center of the rotatable member unit  54  is but also a side above a rotation locus of a rotation shaft of the rotatable member unit  54 . However, as shown in  8   b ) of  FIG. 9 , in the case where a position where the toner T is filled can be arbitrarily designated using a nozzle O or the like, the position of the filling port C is not limited if a filling condition of the toner T for causing the sealing member  52  to be not readily disconnected from the sandwiching portion M is satisfied. Further, also after the filling of the toner T, movement of the toner T is prevented to the possible extent by an attitude of the cartridge B, so that it becomes possible to prevent the sealing member  52  from disconnecting from the sandwiching portion M by the movement of the sealing member  52 . For that reason, also as regards a toner filling amount, the toner may preferably be filled without providing a space in the toner accommodating frame to the possible extent. 
     (Verification Experiment) 
     How a torque (N.m) of the driving shaft  14  during unsealing of the sealing member  52  in this embodiment changes will be verified. As Comparison Example, the case where the sealing member  52  is welded at the fixing portions  23   c ,  23   d ,  23   e ,  23   f  surrounding the toner supply opening  23   a  as shown in (a) of  FIG. 10  is used. 
     In  FIG. 10 , (b) is a graph in which a rotation start time of the driving shaft  14  of the apparatus main assembly A is taken as an origin on an abscissa and a magnitude of a torque is represented by an ordinate and in which progression of the torque from the rotational drive of the driving shaft  14 . In the graph of (b) of  FIG. 10 , a solid line represents Comparison Example and shows the torque during unsealing in the case where the sealing member  52  is welded to an entirety of a periphery of the toner supply opening  23   a . Further, in the graph of (b) of  FIG. 10 , a broken line represents Embodiment 1 and shows the torque during unsealing in the constitution in which the sealing member  52  is sandwiched in the sandwiching portion M. 
     Two peaks t 1  and t 2  where the torque in Comparison Example in (b) of  FIG. 10  increases will be described. The peak t 1  is a torque peak in the case where the welding at the fixing portion  23   f  is eliminated, and the peak t 2  is a torque peak in the case where the welding at the fixing portion  23   c  is eliminated. When these torque peaks are compared with each other, it is understood that in the same constitution, a maximum torque at t 1  is larger than a maximum torque at t 2 . This is because these torques are those immediately after the start of the drive of the driving shaft  14  and therefore the toner T in the toner accommodating frame is not loosened and thus the torque of the rotatable member unit  54  rotating in the toner T is large. On the other hand, at the peak t 2 , the toner T is loosened by the rotatable member and therefore compared with the peak t 1 , the sealing member  52  can be peeled off from the fixing portion  23   c  with a small torque. Similarly, an increased torque peak t 1 ′ in Embodiment 2 (this embodiment) in (b) of  FIG. 10  shows a torque in the case where the sealing member  52  sandwiched in the sandwiching portion M is disconnected from the sandwiching portion M, and it is understood that compared with t 1  in Comparison Example in which the sealing member is welded, the torque becomes small. Further, as regards the peak t 2 , the sealing member is welded in both of Comparison Example and Embodiment 1, and therefore it is understood that the torque is the same. 
     From the above, in the constitution in this embodiment, it becomes possible to suppress a torque peak value and thus to suppress a necessary torque as a whole. 
     Further, comparison and investigation regarding toner leakage from the toner accommodating frame was conducted. As the comparison and investigation regarding the toner leakage, a drop test of the cartridge B was conducted. The drop test is conducted in a packaged state in which the cartridge B is placed in an unused case. Assuming that the cartridge B is transported, the cartridge B is dropped from a height of 100 cm while being in the packaged state, and then whether or not the toner leaks out of the cartridge B is checked. As an object to be compared with that in this embodiment, the cartridge B in the case where the sealing member  52  is welded to the entirety of the periphery of the toner supply opening  23   a  ((a) of  FIG. 10 ) is used similarly as in the case of the measurement of the torque. 
     In the above-described comparison and investigation, in both of the constitutions in Embodiment 1 and Comparison Example, the toner leakage did not generate, and therefore it was confirmed that the toner T was able to be sealed in the toner accommodating frame  23  with no problem. 
     From the comparison and investigation described above, in the constitution in this embodiment, it becomes possible to suppress the torque during unsealing of the sealing member  52  while preventing the toner leakage from the cartridge B. 
     [Embodiment 2] 
     Embodiment 2 is characterized in that in addition to the constitution in Embodiment 1 in which the folded-back portion of the sealing member  52  is sandwiched, sealing is made using a restoring force of the folded-back portion so that the toner leakage can be further prevented. 
     In Embodiment 2, an apparatus main assembly A and an image forming process are the same as those in Embodiment 1, and therefore description of a sandwiching portion M of a developing device unit  20  will be made. 
     (Sandwiching Portion M) 
     In  FIG. 11 , (a) and (b) are sectional views of the developing device unit  20  in this embodiment, in which (a) is the sectional view of an entirety of the developing device unit  20  and (b) is an enlarged view showing the folded-back portion U of the sealing member  52  and a sandwiching portion M in the developing device unit. Cross sections shown in (a) and (b) of  FIG. 11  are planes perpendicular to the toner supply opening  23   a.    
     In this embodiment, as shown in (a) of  FIG. 11 , one end portion  52   b  of the sealing member  52  is welded to the fixing portion  23   c  which is a portion on an upper end of the toner supply opening  23   a  and welded to the side fixing portions  23   d ,  23   e  ((a) of  FIG. 10 ). Further, at the sandwiching portion M which is a portion under a lower end of the toner supply opening  23   a , the sealing member is sandwiched the toner accommodating frame  23  in a state in which the sealing member is folded back with the folded-back portion U as an inflection point thereof. The sandwiching portion M is constituted by a wall  23   g , provided with the toner supply opening  23   a , constituting the toner accommodating frame  23  and a part  23   h , opposing the wall  23   g , of the toner accommodating frame  23 . However, depending on a magnitude of the toner supply opening  23   a , the sealing member  52  is not particularly required to be welded at the fixing portions  23   d ,  23   e . Further, a portion, of the sealing member  52 , sandwiched by the sandwiching portion M is not welded (i.e., nonwelded) in the sandwiching portion M when the sealing member  52  is seen on a plane perpendicular to the toner supply opening  23   a.    
     In this embodiment, different from Embodiment 1, the sealing member  52  is not in the state in which the sealing member  52  is (sharply) folded back with the folded-back portion U as the bottom thereof, but is (loosely) folded back so as to have the inflection point at the folded-back portion U. For that reason, the sealing member  52  is sandwiched in the sandwiching portion M of the toner accommodating frame  23  by using a restoring force F of the sealing member  52 . Herein, the restoring force F refers to a force F (indicated by arrows in (a) of  FIG. 12 ) by which the sealing member  52  is restored to an original state in the case where the sealing member  52  is flexed (bent) using a flexible material as shown in (a) of  FIG. 12 . In this case, a condition in which the restoring force F of the sealing member  52  is obtained and thus the toner T can be sealed in the toner accommodating frame  23  will be described using (b) of  FIG. 12 . 
     A depth D in which the sealing member  52  is sandwiched in the sandwiching portion M may only be required to be not less than a radius R of an arcuate portion, i.e., D&gt;R. This is because, in the case of D≦R, the folded-back portion of the sealing member  52  is shallowly sandwiched in the sandwiching portion M and is likely to be restored to the original state by the restoring force F and therefore is liable to disconnect from the sandwiching portion M when is shallowly sandwiched. 
     Further, as regards a width W of the sandwiching portion M, 2R&gt;W may only be required in order to obtain the restoring force F in the case where the sealing member  52  is folded back. This is also a condition such that similarly as in the case of the sandwiching depth D, the sealing member  52  is shallowly sandwiched in the sandwiching portion M and is prevented from easily disconnecting from the sandwiching portion M. 
     Further, a material of the sealing member  52  may only be required to be flexible, and a thickness thereof is needed to be not less than a thickness in which the restoring force generates and not more than a thickness in which the sealing member  52  can be folded back. Values of these thicknesses are determined depending on the material of the sealing member  52 . 
     From the above, in this embodiment, the depth D of the sandwiching portion M is 10 mm, and the width W of the sandwiching portion M is 5 mm. Further, the thickness L of the sealing member  52  is 100 μm. The material of the sealing member  52  is a flexible material, such as PET, PC or PPS, having an adhesive layer which is melted by heat and thus can be welded to a frame (container). By sandwiching the sealing member  52  in the sandwiching portion M in a folded-back state, the toner T is prevented from leaking out of the toner accommodating frame  23 . 
     (Verification Experiment) 
     How a torque (N.m) of the driving shaft  14  during unsealing of the sealing member  52  in this embodiment changes will be verified. As Comparison Example, the case where the sealing member  52  is welded at the fixing portions  23   c ,  23   d ,  23   e ,  23   f  surrounding the toner supply opening  23   a  as shown in (a) of  FIG. 10  is used. 
       FIG. 13  is a graph in which a rotation start time of the driving shaft  14  of the image forming apparatus main assembly A is taken as an origin on an abscissa and a magnitude of a torque is represented by an ordinate and in which progression of the torque from the rotational drive of the driving shaft  14 . In the graph of (b) of  FIG. 13 , a solid line represents Comparison Example and shows the torque during unsealing in the case where the sealing member  52  is welded to an entirety of a periphery of the toner supply opening  23   a  as shown in (a) of  FIG. 10 . Further, in the graph of  FIG. 13 , a broken line represents Embodiment 2 and shows the torque during unsealing in the constitution in which the sealing member  52  is sandwiched in the sandwiching portion M. 
     Of two peaks t 1  and t 2  where the torque in Comparison Example in  FIG. 13  increases, as described in Embodiment 1, the peak t 1  is a torque peak in the case where the welding at the fixing portion  23   f  is eliminated, and the peak t 2  is a torque peak in the case where the welding at the fixing portion  23   c  is eliminated. Similarly, an increased torque peak t 1 ″ in Embodiment 2 (this embodiment) in  FIG. 13  shows a torque in the case where the sealing member  52  sandwiched in the sandwiching portion M is disconnected from the sandwiching portion M, and it is understood that compared with t 1  in Comparison Example in which the sealing member is welded, the torque becomes small. However, the sealing member  52  is sandwiched using the restoring force F and therefore the torque is larger than the torque in Embodiment 1. Further, as regards the peak t 2 , the sealing member is welded in both of Comparison Example and Embodiment 1, and therefore it is understood that the torque is the same. 
     From the above, in the constitution in this embodiment, it becomes possible to suppress a torque peak value and thus to suppress a necessary torque as a whole. 
     Further, comparison and investigation regarding toner leakage from the toner accommodating frame was conducted. As the comparison and investigation regarding the toner leakage, a drop test of the cartridge B was conducted. The drop test is conducted in a packaged state in which the cartridge B is placed in an unused case. Assuming that the cartridge B is transported, the cartridge B is dropped from a height of 100 cm while being in the packaged state, and then whether or not the toner leaks out of the cartridge B is checked. As an object to be compared with that in this embodiment, the cartridge B in the case where the sealing member  52  is welded to the entirety of the periphery of the toner supply opening  23   a  ((a) of  FIG. 10 ) is used similarly as in the case of the measurement of the torque. 
     In the above-described comparison and investigation, in both of the constitutions in Embodiment 2 and Comparison Example, the toner leakage did not generate, and therefore it was confirmed that the toner T was able to be sealed in the toner accommodating frame  23  with no problem. Further, compared with Embodiment 1, the sealing is made using the restoring force F in this embodiment, and therefore the sealing can be made more effectively against the toner leakage. 
     From the comparison and investigation described above, in the constitution in this embodiment, it becomes possible to suppress the torque during unsealing of the sealing member  52  while further preventing the toner leakage from the cartridge B. 
     [Embodiment 3] 
     Embodiment 3 is characterized in that in addition to the constitution in Embodiment 2 in which the sealing is made using the restoring force F of the sealing member  52 , also at a portion above the opening  23   a , the folded-back portion is similarly sandwiched and the sealing is made using the restoring force F of the sealing member  52 . 
     In Embodiment 3, an apparatus main assembly A and an image forming process are the same as those in Embodiment 1, and therefore description of a sandwiching portion M of a developing device unit  20  will be made. 
     (Sandwiching Portion M) 
     In  FIG. 14 , (a) to (c) are sectional views of the developing device unit  20  in this embodiment, in which (a) is the sectional view of an entirety of the developing device unit  20 , and (b) and (c) are enlarged views showing folded-back portions U, V of the sealing member  52  and sandwiching portions M, N in the developing device unit. Cross sections shown in (a) to (c) of  FIG. 14  are planes perpendicular to the toner supply opening  23   a.    
     In this embodiment, as shown in (a) and (b) of  FIG. 14 , one end portion  52   b  of the sealing member  52  is sandwiched in the sandwiching portion N which is a portion on an upper end of the toner supply opening  23   a  in a state in which the sealing member  52  is folded back with the folded-back portion V as an inflection point thereof. For this reason, using the restoring force F, the sandwiching portion N sandwiches the sealing member  52 . Further, at the sandwiching portion M which is a portion under a lower end of the toner supply opening  23   a , the sealing member is sandwiched in a state in which the sealing member is folded back with the folded-back portion U as an inflection point thereof. For that reason, similarly as in Embodiment 2, the sealing member  52  is sandwiched in the sandwiching portion M by using the restoring force F. Further, although the side fixing portions  23   d ,  23   e  are not shown in  FIG. 14 , at the periphery of the toner supply opening  23   a , the sealing member  52  is welded to the side fixing portions  23   d ,  23   e  sandwiching the toner supply opening  23   a  in this embodiment. However, depending on a magnitude of the toner supply opening  23   a , a constitution in which the fixing portions  23   d ,  23   e  are not provided, i.e., a constitution in which the sealing member  52  is not welded may also be employed. Further, a portion, of the sealing member  52 , sandwiched by the sandwiching portion M is not welded (i.e., nonwelded) in each of the sandwiching portions M, N when the sealing member  52  is seen on a plane perpendicular to the toner supply opening  23   a . Each of the sandwiching portions M, N is, similarly as in the above-described embodiments, constituted by the wall  23   g , provided with the toner supply opening  23   a , constituting the toner accommodating frame  23  and the part  23   h , opposing the wall  23   g , of the toner accommodating frame  23 . 
     As a condition in which the restoring force F of the sealing member  52  is obtained and thus the toner can be sealed in the toner accommodating frame  23 , similarly as in Embodiment 2, as shown in (b) of  FIG. 12 , a depth D in which the sealing member  52  is sandwiched in the sandwiching portion M may only be required to be not less than a radius R of an arcuate portion, i.e., D&gt;R. This is because, in the case of D≦R, the folded-back portion of the sealing member  52  is shallowly sandwiched in the sandwiching portion M and is likely to be restored to the original state by the restoring force F and therefore is liable to disconnect from the sandwiching portion M when is shallowly sandwiched. 
     Further, as regards a width W of the sandwiching portion M, 2R&gt;W may only be required in order to obtain the restoring force F in the case where the sealing member  52  is folded back. This is also a condition such that similarly as in the case of the sandwiching depth D, the sealing member  52  is shallowly sandwiched in the sandwiching portion M and is prevented from easily disconnecting from the sandwiching portion M. 
     Further, a material of the sealing member  52  may only be required to be flexible, and a thickness thereof is needed to be not less than a thickness in which the restoring force generates and not more than a thickness in which the sealing member  52  can be folded back. Values of these thicknesses are determined depending on the material of the sealing member  52 . 
     Similarly, also at the sandwiching portion N, only the direction is changed from the downward direction to the upward direction, and therefore when a condition similar to the condition in the case of the sandwiching portion M is satisfied, the toner T can be sealed in the toner accommodating frame  23  by using the restoring force F. 
     From the above, in this embodiment, the depth D of each of the sandwiching portions M, N is 10 mm, and the width W of each of the sandwiching portions M, N is 5 mm. Further, the thickness L of the sealing member  52  is 100 μm. The material of the sealing member  52  is a flexible material, such as PET, PC or PPS, having an adhesive layer which is melted by heat and thus can be welded to the container. By sandwiching the sealing member  52  in each of the sandwiching portions M, N in a folded-back state, the toner T is prevented from leaking out of the toner accommodating frame  23 . 
     (Verification Experiment) 
     How a torque (N.m) of the driving shaft  14  during unsealing of the sealing member  52  in this embodiment changes will be verified. As Comparison Example, the case where the sealing member  52  is welded at the fixing portions  23   c ,  23   d ,  23   e ,  23   f  surrounding the toner supply opening  23   a  as shown in (a) of  FIG. 10  is used. 
       FIG. 15  is a graph in which a rotation start time of the driving shaft  14  of the apparatus main assembly A is taken as an origin on an abscissa and a magnitude of a torque is represented by an ordinate and in which progression of the torque from the rotational drive of the driving shaft  14 . In the graph of (b) of  FIG. 15 , a solid line represents Comparison Example and shows the torque during unsealing in the case where the sealing member  52  is welded to an entirety of a periphery of the toner supply opening  23   a  as shown in (a) of  FIG. 10 . Further, in the graph of  FIG. 15 , a broken line represents Embodiment 3 and shows the torque during unsealing in the constitution in which the sealing member  52  is sandwiched in each of the sandwiching portions M, N. 
     Of two peaks t 1  and t 2  where the torque in Comparison Example in  FIG. 15  increases, as described in Embodiment 1, the peak t 1  is a torque peak in the case where the welding at the fixing portion  23   f  is eliminated, and the peak t 2  is a torque peak in the case where the welding at the fixing portion  23   c  is eliminated. Similarly, an increased torque peak t 3  in Embodiment 3 (this embodiment) in  FIG. 15  shows a torque in the case where the sealing member  52  sandwiched in the sandwiching portion M is disconnected from the sandwiching portion M, and it is understood that compared with t 1  in Comparison Example in which the sealing member is welded, the torque becomes small. Further, an increased torque peak T 4  in Embodiment 3 (this embodiment) in  FIG. 15  shows a torque in the case where the sealing member  52  sandwiched in the sandwiching portion N is disconnected from the sandwiching portion N, and it is understood that compared with t 2  in Comparison Example in which the sealing member is welded, the torque becomes small. 
     From the above, in the constitution in this embodiment, it becomes possible to suppress a torque peak value and thus to suppress a necessary torque as a whole. 
     Further, comparison and investigation regarding toner leakage from the toner accommodating frame was conducted. As the comparison and investigation regarding the toner leakage, a drop test of the cartridge B was conducted. The drop test is conducted in a packaged state in which the cartridge B is placed in an unused case. Assuming that the cartridge B is transported, the cartridge B is dropped from a height of 100 cm while being in the packaged state, and then whether or not the toner leaks out of the cartridge B is checked. As an object to be compared with that in this embodiment, the cartridge B in the case where the sealing member  52  is welded to the entirety of the periphery of the toner supply opening  23   a  ((a) of  FIG. 10 ) is used similarly as in the case of the measurement of the torque. 
     In the above-described comparison and investigation, in both of the constitutions in Embodiment 3 and Comparison Example, the toner leakage did not generate, and therefore it was confirmed that the toner T was able to be sealed in the toner accommodating frame  23  with no problem in use. 
     From the comparison and investigation described above, according to this embodiment, it becomes possible to suppress the torque during unsealing of the sealing member  52  while further preventing the toner leakage from the cartridge B. 
     Further, as shown in  FIG. 16 , even when a constitution opposite to the constitution shown in  FIG. 14  in that a direction of folding back of the sealing member  52  in the sandwiching portion N at the portion above the toner supply opening  23   a  is employed, the torque change device is the same as that in this embodiment, so that an effect similar to the effect of the present invention can be obtained. In this case, at the periphery of the toner supply opening  23   a , the fixing portion  23   b  is not provided, so that there was no problem also in terms of the toner leakage and therefore an effects similar to the effect of the present invention was obtained. 
     [Embodiment 4] 
     Embodiment 4 is characterized in that in addition to the constitution in Embodiment 2 in which the folded-back portion of the sealing member  52  is sandwiched at the portion under the opening, a sandwiching opening M′ is made narrower than that in Embodiment 2, so that the sealing member  52  does not readily disconnect from the sandwiching portion M and thus the toner does not readily leak out further by narrowing a sandwiching port M′ compared with that in Embodiment 2. 
     In Embodiment 4, an apparatus main assembly A and an image forming process are the same as those in Embodiment 1, and therefore description of a sandwiching portion M of a developing device unit  20  will be made. 
     (Sandwiching Portion M) 
     In  FIG. 17 , (a) and (b) are sectional views of the developing device unit  20  in this embodiment, in which (a) is the sectional view of an entirety of the developing device unit  20  and (b) is an enlarged view showing the folded-back portion U of the sealing member  52  and a sandwiching portion M and the sandwiching port M′ in the developing device unit. Cross sections shown in (a) and (b) of  FIG. 17  are planes perpendicular to the toner supply opening  23   a.    
     In this embodiment, as shown in (a) of  FIG. 17 , one end portion  52   b  of the sealing member  52  is welded to the fixing portion  23   c  which is a portion on an upper end of the toner supply opening  23   a  and welded to the side fixing portions  23   d ,  23   e  ((a) of  FIG. 10 ). Further, at the sandwiching portion M which is a portion under a lower end of the toner supply opening  23   a , the sealing member is sandwiched the toner accommodating frame  23  in a state in which the sealing member is folded back with the folded-back portion U as an inflection point thereof. However, depending on a magnitude of the toner supply opening  23   a , the fixing portions  23   d ,  23   e  are not needed. Further, in Embodiment 4, in addition to the sandwiching of the sealing member  52  in the sandwiching portion M by using the restoring force F as in Embodiment 2, the sandwiching port M′ which is an entering port for the sealing member  52  at the sandwiching portion M. Further, a portion, of the sealing member  52 , sandwiched at the sandwiching portion M and the sandwiching port M′ is not welded in the sandwiching portion as seen in a plane perpendicular to the toner supply opening  23   a . The sandwiching portion M is constituted by a wall  23   g , provided with the toner supply opening  23   a , constituting the toner accommodating frame  23  and a part  23   h , opposing the wall  23   g , of the toner accommodating frame  23 . 
     For that reason, as a condition at the sandwiching portion M, when a width of the sandwiching portion M is W and a width of the sandwiching port M′ is W′, W′&gt;W is satisfied. Further, when the width W′ becomes excessively narrow, then the sealing member  52  does not readily disconnect from the sandwiching portion M, and therefore the width W′ is required to be not less than twice the thickness L of the sealing member  52 . For that reason, as a condition of the width W′ of the sandwiching port M′, 2L&lt;W′&lt;W is satisfied. Further, when a distance from a lower end portion of the sandwiching port M′ to the folded-back portion U of the sealing member  52  is a sandwiching depth D′ of the sealing member  52  in the sandwiching portion M, the sandwiching depth D′ may only be required to be not less than a radius R of an arcuate portion, i.e., D′&gt;R. This is because, similarly as in Embodiment 2, in the case of D′≦R, the folded-back portion of the sealing member  52  is shallowly sandwiched in the sandwiching portion M and is likely to be restored to the original state by the restoring force F and therefore is liable to disconnect from the sandwiching portion M when is shallowly sandwiched. 
     From the above, in this embodiment, the depth D of the sandwiching portion M is 10 mm, and the width W of the sandwiching portion M is 5 mm. Further, the width W′ of the sandwiching port M′ is 2 mm. Further, the thickness L of the sealing member  52  is 100 μm. The material of the sealing member  52  is a flexible material, such as PET, PC or PPS, having an adhesive layer which is melted by heat and thus can be welded to the container. By sandwiching the sealing member  52  in the sandwiching portion M and the sandwiching port M′ in a folded-back state, the toner T is prevented from leaking out of the toner accommodating frame  23 . 
     (Verification Experiment) 
     How a torque (N.m) of the driving shaft  14  during unsealing of the sealing member  52  in this embodiment changes will be verified. As Comparison Example 1, a torque in the case where the sealing member  52  is welded at the fixing portions  23   c ,  23   d ,  23   e ,  23   f  surrounding the toner supply opening  23   a  as shown in (a) of  FIG. 10  is shown. As Comparison Example 2, a torque in the case where the sealing member  52  is sandwiched by the restoring force F at the sandwiching portion M in Embodiment 2 ( FIG. 11 ) is shown. 
       FIG. 18  is a graph in which a rotation start time of the driving shaft  14  of the apparatus main assembly A is taken as an origin on an abscissa and a magnitude of a torque is represented by an ordinate and in which progression of the torque from the rotational drive of the driving shaft  14 . In the graph of (b) of  FIG. 18 , a solid line represents Comparison Example and shows the torque during unsealing in the case where the sealing member  52  is welded to an entirety of a periphery of the toner supply opening  23   a  as shown in (a) of  FIG. 10 . Further, in the graph of  FIG. 18 , a broken line represents Comparison Example 2 and shows the torque in the case where the sealing member  52  is sandwiched by the restoring force F at the sandwiching portion M in Embodiment 2. In the graph of  FIG. 18 , a chain line represents a constitution of Embodiment 4 (this embodiment) and shows the torque during unsealing in the case where the sandwiching port M′ is made narrower than the sandwiching portion M. 
     In  FIG. 18 , an increased torque peak t 5  in this embodiment is the torque in the case where the sealing member  52  sandwiched in the sandwiching portion M disconnects from the sandwiching portion M, and an increased torque peak t 6  shows the torque in the case where the sealing member  52  welded to the sandwiching portion  23   c  is peeled off from the fixing portion  23   c . A torque peak t 1  in Comparison Example 1 shows the torque in the case where the sealing member  52  is peeled off from the fixing portion  23   f , and a torque peak t 2  shows the torque in the case where the sealing member  52  is peeled off from the fixing portion  23   c . Further, a torque peak t 1 ′ in Comparison Example 2 is the torque in the case where the sealing member  52  is peeled off from the sandwiching portion M, and a torque peak t 2 ′ shows the torque in the case where the sealing member  52  is peeled off from the sandwiching portion  23   c . Particularly, when the torque peaks t 1 , t 1 ′ and t 5  are compared, it is understood that t 5  is larger than t 1 ′ and is smaller than t 1 . Further, the torque peaks t 2 , t 2 ′ and t 6  have the same constitution, and therefore it is understood that the torques are the same. 
     From the above, in the constitution in this embodiment, it becomes possible to suppress a torque peak value compared with the case of the welding in Comparison Example 1 and thus to suppress a necessary torque as a whole. 
     Further, comparison and investigation regarding toner leakage from the toner accommodating frame was conducted. As the comparison and investigation regarding the toner leakage, a drop test of the cartridge B was conducted. The drop test is conducted in a packaged state in which the cartridge B is placed in an unused case. Assuming that the cartridge B is transported, the cartridge B is dropped from a height of 100 cm while being in the packaged state, and then whether or not the toner leaks out of the cartridge B is checked. As an object to be compared with that in this embodiment, as Comparison Example, the cartridge B in the case where the sealing member  52  is welded to the entirety of the periphery of the toner supply opening  23   a  ((a) of  FIG. 10 ) is used similarly as in the case of the measurement of the torque. 
     In the above-described comparison and investigation, in both of the constitutions in Embodiment 4 and Comparison Example, the toner leakage did not generate, and therefore it was confirmed that the toner T was able to be sealed in the toner accommodating frame  23  with no problem in use. 
     From the comparison and investigation described above, in the constitution in this embodiment, it becomes possible to suppress the torque during unsealing of the sealing member  52  while further preventing the toner leakage from the cartridge B. 
     [Embodiment 5] 
     Embodiment 5 is characterized in that in addition to the constitution in Embodiment 4 in which the sealing member  52  does not readily disconnect from the sandwiching portion M by narrowing the sandwiching port M′, the periphery of the sandwiching port M′ is formed with a sponge member and the sealing member  52  is sandwiched in a folded-back state. As a result, the torque during unsealing is suppressed while the sealing member  52  does not readily disconnect through the sandwiching port M′. 
     In Embodiment 5, an image forming apparatus main assembly A and an image forming process are the same as those in Embodiment 1, and therefore description of a sandwiching portion M of a developing device unit  20  will be made. 
     (Sandwiching Portion M) 
     In  FIG. 19 , (a) and (b) are sectional views of the developing device unit  20  in this embodiment, in which (a) is the sectional view of an entirety of the developing device unit  20  and (b) is an enlarged view showing the folded-back portion U of the sealing member  52 , a sandwiching portion M and the sandwiching port M′ in the developing device unit. Cross sections shown in (a) and (b) of  FIG. 19  are planes perpendicular to the toner supply opening  23   a.    
     In this embodiment, as shown in (a) of  FIG. 19 , one end portion  52   b  of the sealing member  52  is welded to the fixing portion  23   c  which is a portion on an upper end of the toner supply opening  23   a  and welded to the side fixing portions  23   d ,  23   e  ((a) of  FIG. 10 ). However, depending on a magnitude of the toner supply opening  23   a , the sealing member  52  is not required to be welded at the fixing portions  23   d ,  23   e . Further, at the sandwiching portion M which is a portion under a lower end of the toner supply opening  23   a , the sealing member is sandwiched the toner accommodating frame  23  in a state in which the sealing member is folded back with the folded-back portion U as an inflection point thereof. A portion, of the sealing member  52 , sandwiched at the sandwiching portion M is not welded in the sandwiching portion M as seen in a plane perpendicular to the toner supply opening  23   a . In Embodiment 5, as in Embodiment 4, the constitution in which the sandwiching port M′ is narrowed and the periphery of the sandwiching port M′ is formed with a sponge member Q (hatched portion of  FIG. 19 ) to sandwich the sealing member  52  is employed. The sandwiching portion M is constituted by a wall  23   g , provided with the toner supply opening  23   a , constituting the toner accommodating frame  23  and a part  23   h , opposing the wall  23   g , of the toner accommodating frame  23 . At the sandwiching port M′, the wall  23   g  and the sponge member Q oppose each other. For that reason, as a condition of the sandwiching port M′, when a width of the sandwiching portion M is W and a width of the sandwiching port M′ is W′, W′&gt;W is satisfied. In Embodiment 4, the lower limit of the width W′ was twice the thickness L of the sealing member  52 , but in this embodiment, the periphery of the sandwiching port M′ is formed using the sponge member Q, and therefore the lower limit of the width W′ can be made further small. However, the width W of the sandwiching portion M is required to be larger than twice the thickness L of the sealing member  52 , and therefore there is a need to satisfy 2L&lt;W. 
     From the above, in this embodiment, as a condition of the sandwiching port M′, W′&lt;W and 2L&lt;W are satisfied. Specifically, W=10 mm, W′=5 mm and L=100 μm are set. The material of the sealing member  52  is a flexible material, such as PET, PC or PPS, having an adhesive layer which is melted by heat and thus can be welded to a frame (container). 
     (Verification Experiment) 
     How a torque (N.m) of the driving shaft  14  during unsealing of the sealing member  52  in this embodiment changes will be verified. As Comparison Example 1, a torque in the case where the sealing member  52  is welded at the fixing portions  23   c ,  23   d ,  23   e ,  23   f  surrounding the toner supply opening  23   a  as shown in (a) of  FIG. 10  is shown. As Comparison Example 2, a torque in the case where the sealing member  52  is sandwiched by the restoring force F at the sandwiching portion M in Embodiment 2 ( FIG. 11 ) is shown. 
       FIG. 20  is a graph in which a rotation start time of the driving shaft  14  of the apparatus main assembly A is taken as an origin on an abscissa and a magnitude of a torque is represented by an ordinate and in which progression of the torque from the rotational drive of the driving shaft  14 . In the graph of (b) of  FIG. 20 , a solid line represents Comparison Example and shows the torque during unsealing in the case where the sealing member  52  is welded to an entirety of a periphery of the toner supply opening  23   a  as shown in (a) of  FIG. 10 . Further, in the graph of  FIG. 20 , a broken line represents Comparison Example 2 and shows the torque in the case where the sealing member  52  is sandwiched by the restoring force F at the sandwiching portion M in Embodiment 2. In the graph of  FIG. 20 , a chain line represents a constitution of Embodiment 4 (this embodiment) and shows the torque during unsealing in the case where the sandwiching port M′ is made narrower than the sandwiching portion M and the sponge member Q is used. 
     In  FIG. 20 , an increased torque peak t 7  in this embodiment is the torque in the case where the sealing member  52  sandwiched in the sandwiching portion M disconnects from the sandwiching portion M, and an increased torque peak t 8  shows the torque in the case where the sealing member  52  is peeled off from the fixing portion  23   c . A torque peak t 1  in Comparison Example 1 shows the torque in the case where the sealing member  52  is peeled off from the fixing portion  23   f , and a torque peak t 2  shows the torque in the case where the sealing member  52  is peeled off from the fixing portion  23   c . Further, a torque peak t 1 ′ in Comparison Example 2 is the torque in the case where the sealing member  52  is peeled off from the sandwiching portion M, and a torque peak t 2 ′ is the torque in the case where the sealing member  52  is peeled off from the sandwiching portion  23   c . Particularly, when the torque peaks t 1 , t 1 ′ and t 7  are compared, in this embodiment, the sealing member  52  is sandwiched more tightly than in Comparison Example 2 and therefore, it is understood that the torque peak t 7  in this embodiment is larger than the torque peak t 1 ′ in Comparison Example 2. However, it is understood that compared with the torque peak t 1  in Embodiment 1, the torque peak t 7  is not the torque peak in the case of the welding and thus is lower than the torque peak t 1  as a peak value. Further, the torque peaks t 2 , t 2 ′ and t 8  have the same constitution, and therefore it is understood that the torque peaks are the same. 
     From the above, in the constitution in this embodiment, it becomes possible to suppress a torque peak value compared with the case of the welding in Comparison Example 1 and thus to suppress a necessary torque as a whole. 
     Further, comparison and investigation regarding toner leakage from the toner accommodating frame  23  was conducted. As the comparison and investigation regarding the toner leakage, a drop test of the cartridge B was conducted. The drop test is conducted in a packaged state in which the cartridge B is placed in an unused case. Assuming that the cartridge B is transported, the cartridge B is dropped from a height of 100 cm while being in the packaged state, and then whether or not the toner leaks out of the cartridge B is checked. As an object to be compared with that in this embodiment, as Comparison Example, the cartridge B in the case where the sealing member  52  is welded to the entirety of the periphery of the toner supply opening  23   a  ((a) of  FIG. 10 ) is used similarly as in the case of the measurement of the torque. 
     In the above-described comparison and investigation, in both of the constitutions in Embodiment 5 and Comparison Example, the toner leakage did not generate, and therefore it was confirmed that the toner T was able to be sealed in the toner accommodating frame  23  with no problem in use. 
     From the comparison and investigation described above, in the constitution in this embodiment, it becomes possible to suppress the torque during unsealing of the sealing member  52  while further preventing the toner leakage from the cartridge B. 
     [Embodiment 6] 
     Embodiment 6 is characterized in that different from Embodiment 5 in which the periphery of the sandwiching port M′ is formed with the sponge member Q, the sponge member Q is mounted to define the opening to sandwich the sealing member  52 . 
     In Embodiment 6, an apparatus main assembly A and an image forming process are the same as those in Embodiment 1, and therefore description of a sandwiching portion M of a developing device unit  20  will be made. 
     (Sandwiching Portion M) 
     In  FIG. 21 , (a) and (b) are sectional views of the developing device unit  20  in this embodiment, in which (a) is the sectional view of an entirety of the developing device unit  20  and (b) is an enlarged view showing the folded-back portion U of the sealing member  52  and a sandwiching portion M in the developing device unit. Cross sections shown in (a) and (b) of  FIG. 21  are planes perpendicular to the toner supply opening  23   a.    
     In this embodiment, as shown in (a) of  FIG. 21 , one end portion  52   b  of the sealing member  52  is welded to the fixing portion  23   c  which is a portion on an upper end of the toner supply opening  23   a  and welded to the side fixing portions  23   d ,  23   e  ((a) of  FIG. 10 ). Further, at the sandwiching portion M which is a portion under a lower end of the toner supply opening  23   a , the sealing member is sandwiched in a state in which the sealing member is folded back at the folded-back portion U. However, depending on a magnitude of the toner supply opening  23   a , the sealing member  52  is not particularly required to be welded at the fixing portions  23   d ,  23   e . Further, a portion, of the sealing member  52 , sandwiched by the sandwiching portion M is not welded (i.e., nonwelded) in the sandwiching portion M when the sealing member  52  is seen on a plane perpendicular to the toner supply opening  23   a.    
     Further, in this embodiment, an assisting member  53  is provided at a portion blow the toner supply opening  23   a  and then the sponge member Q is mounted on the assisting member  53 . The sponge member Q is assisted by the assisting member  53  from a side opposite from a contact portion with the sealing member  52 . The sandwiching portion M is constituted by the wall  23   g , provided with the toner supply opening  23   a , constituting the toner accommodating frame  23  and by the sponge member Q provided opposed to the wall  23   g . Then, the folded-back portion of the sealing member  52  is sandwiched by the wall  23   g  and the sponge member Q, so that the sealing member  52  does not readily disconnect from the sandwiching portion M and thus the toner leakage is prevented. Further, in this embodiment, the assisting member  53  is provided using a SUS plate as shown in  FIG. 21  and is fixed with a double-side tape at the portion below the toner supply opening  23   a . When the width of the sandwiching portion M is W and the thickness of the sealing member  52  is L, in this embodiment, as a condition in which the sealing member  52  is sandwiched by the width  23   g  and the sponge member Q, 2L&gt;W is satisfied. Specifically, in this embodiment, the width W of the sandwiching portion M and the thickness L of the sealing member  52  are 180 μm and 100 μm, respectively. The material of the sealing member  52  is a flexible material, such as PET, PC or PPS, having an adhesive layer which is melted by heat and thus can be welded to a frame (container). 
     (Verification Experiment) 
     How a torque (N.m) of the driving shaft  14  during unsealing of the sealing member  52  in this embodiment changes will be verified. As Comparison Example 1, a torque in the case where the sealing member  52  is welded at the fixing portions  23   c ,  23   d ,  23   e ,  23   f  surrounding the toner supply opening  23   a  as shown in (a) of  FIG. 10  is shown. As Comparison Example 2, a torque in the case where the sealing member  52  is sandwiched by the restoring force F at the sandwiching portion M in Embodiment 2 ( FIG. 11 ) is shown. 
       FIG. 22  is a graph in which a rotation start time of the driving shaft  14  of the apparatus main assembly A is taken as an origin on an abscissa and a magnitude of a torque is represented by an ordinate and in which progression of the torque from the rotational drive of the driving shaft  14 . In the graph of (b) of  FIG. 22 , a solid line represents Comparison Example and shows the torque during unsealing in the case where the sealing member  52  is welded to an entirety of a periphery of the toner supply opening  23   a  as shown in (a) of  FIG. 10 . Further, in the graph of  FIG. 22 , a broken line represents Comparison Example 2 and shows the torque in the case where the sealing member  52  is sandwiched by the restoring force F at the sandwiching portion M in Embodiment 2. In the graph of  FIG. 22 , a chain line represents a constitution of Embodiment 4 (this embodiment) and shows the torque during unsealing in the case where the sandwiching sealing member  52  is sandwiched using the sponge member Q mounted on the assisting member  53 . 
     In  FIG. 22 , a torque peak t 9  in this embodiment is the torque in the case where the sealing member  52  sandwiched using the sponge member Q disconnects from the sandwiching portion M, and a torque peak t 10  is the torque in the case where the sealing member  52  is peeled off from the fixing portion  23   c . A torque peak t 1  in Comparison Example 1 is the torque in the case where the sealing member  52  is peeled off from the fixing portion  23   f , and a torque peak t 2  is the torque in the case where the sealing member  52  is peeled off from the fixing portion  23   c . Further, a torque peak t 1 ′ in Comparison Example 2 is the torque in the case where the sealing member  52  is peeled off from the sandwiching portion M, and a torque peak t 2 ′ is the torque in the case where the sealing member  52  is peeled off from the sandwiching portion  23   c . When the torque peaks t 1 , t 1 ′ and t 9  are compared, it is understood that the torque peak t 9  is larger than the torque peak t 1  in the case of the welding. Further, in this embodiment, the sealing member  52  is sandwiched more tightly than in Comparison Example 2 and therefore it is understood that the torque peak t 9  is larger than the torque peak t 1 ′ in Comparison Example 2. Further, the torque peaks t 2 , t 2 ′ and t 10  have the same constitution, and therefore it is understood that the torques are the same. 
     From the above, in the constitution in this embodiment, it becomes possible to suppress a torque peak value compared with the case of the welding in Comparison Example 1 and thus to suppress a necessary torque as a whole. 
     Further, comparison and investigation regarding toner leakage from the toner accommodating frame  23  was conducted. As the comparison and investigation regarding the toner leakage, a drop test of the cartridge B was conducted. The drop test is conducted in a packaged state in which the cartridge B is placed in an unused case. Assuming that the cartridge B is transported, the cartridge B is dropped from a height of 100 cm while being in the packaged state, and then whether or not the toner leaks out of the cartridge B is checked. As an object to be compared with that in this embodiment, as Comparison Example, the cartridge B in the case where the sealing member  52  is welded to the entirety of the periphery of the toner supply opening  23   a  ((a) of  FIG. 10 ) is used similarly as in the case of the measurement of the torque. 
     In the above-described comparison and investigation, in both of the constitutions in Embodiment 6 and Comparison Example, the toner leakage did not generate, and therefore it was confirmed that the toner T was able to be sealed in the toner accommodating frame  23  with no problem in use. 
     From the comparison and investigation described above, in the constitution in this embodiment, it becomes possible to suppress the torque during unsealing of the sealing member  52  while further preventing the toner leakage from the cartridge B. 
     [Other Embodiments] 
     In the above-described embodiments, the process cartridge including the developing device unit was described as an example, but the present invention is not limited thereto. Separately from the process cartridge including the photosensitive drum, a developing device detachably mountable to the image forming apparatus main assembly may also be independently provided. Alternatively, a developer container such as a toner bottle including the toner accommodating frame provided with the opening and the sealing member for sealing the opening may also be used. 
     In the above-described embodiments, as the process cartridge detachably mountable to the image forming apparatus main assembly, a process cartridge prepared by integrally assembling the photosensitive drum and, as the process means actable on the photosensitive drum, the charging means, the developing means and the cleaning means into a unit was described as an example. However, the present invention is not limited thereto. The process cartridge may also be a process cartridge integrally including in addition to the photosensitive drum and the developing means, either one of the charging means and the cleaning means as a unit. 
     Further, in the above-described embodiments, as the image forming apparatus, the printer was described as an example, but the present invention is not limited thereto. For example, other image forming apparatuses such as a copying machine, a facsimile machine and a multi-function machine having a combination of functions as these machines may also be used. By applying the present invention to these image forming apparatuses, a similar effect can be obtained. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2015-105995 filed on May 26, 2015, which is hereby incorporated by reference herein in its entirety.