Patent Publication Number: US-11392057-B2

Title: Developing apparatus having a flexible developer conveyor

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a developing apparatus to be used in an electrophotographic image forming apparatus. 
     Description of the Related Art 
     In an image forming apparatus that uses an electrophotographic image forming method, developer is typically stored in a developer container and successively supplied to a developing apparatus. The developer is typically conveyed from the developer container to the developing apparatus by using a rotational agitation member, which includes a flexible agitation sheet. 
     The agitation member is supported inside the developer container. As the agitation member rotates, the flexible agitation sheet may transition repeatedly between a state, in which the agitation sheet is in contact with the frame of the developer container and is thus bent, and a state, in which the agitation sheet is separate from the frame and released from bending. The difference between bent state and release state can be great especially with a downsized developer container, thus increasing the fatigue of the agitation sheet. In this respect, Japanese Patent Application Publication No. 2015-129812 describes a configuration including ribs that come into contact with the agitation sheet to prevent the release noise generated when the sheet is released. 
     SUMMARY OF THE INVENTION 
     The present invention further improves conventional techniques, and it is an object of the present invention to provide a developing apparatus that is downsized and has an increased capacity but still suppresses the fatigue of agitation sheets. 
     To achieve the above objective, a developing apparatus according to the present invention includes: 
     a developing container having a first opening and a second opening; 
     a lid fixed to the developing container so as to close the first opening, the lid defining, together with the developing container, a storage space for developer; 
     a developing roller provided so as to face the second opening; and 
     a conveyance member configured to convey a toner toward the developing roller through the second opening in the developing container, the conveyance member including a flexible sheet and a support member that supports the sheet and is rotatable about a rotation axis together with the sheet, the sheet having a first distance between the rotation axis and an edge of the sheet in a direction orthogonal to the rotation axis in a state in which the sheet is unbent, 
     wherein the lid includes:
         a corner portion that, as viewed in a direction along the rotation axis, extends the storage space outward of an imaginary circle with a radius of the first distance centered on the rotational axis; and   a contact portion that protrudes from the corner portion to an inner side of the imaginary circle and is configured to come into contact with the rotating sheet.       

     As described above, the present invention provides a developing apparatus that is downsized and has an increased capacity but still suppresses the fatigue of agitation sheets. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of the principal section of a developing unit; 
         FIG. 2  is a cross-sectional view of an apparatus main body and a cartridge of an image forming apparatus; 
         FIG. 3  is a cross-sectional view of the cartridge; 
         FIG. 4  is a perspective view illustrating the configuration of the cartridge; 
         FIG. 5  is a perspective view illustrating the configuration of the cartridge; 
         FIGS. 6A and 6B  are cross-sectional views of guide portions of the image forming apparatus for illustrating the attachment of the cartridge; 
         FIGS. 7A and 7B  are cross-sectional views of the image forming apparatus for illustrating the positioning of the cartridge; 
         FIGS. 8A to 8D  are perspective views illustrating a configuration in which the cartridge receives driving force from the apparatus main body; 
         FIG. 9  is a perspective view illustrating the configuration of the developing unit; 
         FIG. 10  is a cross-sectional view of the principal section of the developing unit; 
         FIG. 11  is a cross-sectional view of the principal section of the developing unit; 
         FIG. 12  is a cross-sectional view of the principal section of a developing unit; and 
         FIG. 13  is a cross-sectional view of the principal section of a developing unit. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, a description will be given, with reference to the drawings, of embodiments (examples) of the present invention. However, the sizes, materials, shapes, their relative arrangements, or the like of constituents described in the embodiments may be appropriately changed according to the configurations, various conditions, or the like of apparatuses to which the invention is applied. Therefore, the sizes, materials, shapes, their relative arrangements, or the like of the constituents described in the embodiments do not intend to limit the scope of the invention to the following embodiments. 
     First Embodiment 
     Referring to the drawings, an embodiment of the present invention is now described. 
     A direction along the rotation axis of the electrophotographic photosensitive drum is referred to as a longitudinal direction. In the longitudinal direction, the side in which the electrophotographic photosensitive drum receives driving force from the image forming apparatus main body is referred to as a drive side, and the opposite side is referred to as a non-drive side. 
     Referring to  FIGS. 2 and 3 , the overall configuration and an image formation process are now described.  FIG. 2  is a cross-sectional view of an apparatus main body (electrophotographic image forming apparatus main body, image forming apparatus main body) A and a process cartridge (hereinafter referred to as a cartridge B) of the electrophotographic image forming apparatus according to the embodiment of the present invention.  FIG. 3  is a cross-sectional view of the cartridge B. The apparatus main body A is a portion of the electrophotographic image forming apparatus excluding the cartridge B. 
     Overall Configuration of Electrophotographic Image Forming Apparatus 
     The electrophotographic image forming apparatus (image forming apparatus) shown in  FIG. 2  is a laser beam printer using an electrophotographic technique in which the cartridge B is attached to the apparatus main body A in a detachable manner. When the cartridge B is attached to the apparatus main body A, an exposure apparatus  3  (laser scanner unit) is arranged that forms latent images on an electrophotographic photosensitive drum  62 , which serves as an image bearing member of the cartridge B. A sheet tray  4 , which is arranged under the cartridge B, stores recording medium such as recording paper or plastic sheet (hereinafter referred to as sheet material PA) on which images are formed. The electrophotographic photosensitive drum  62  is a photosensitive member (electrophotographic photosensitive member) used to form electrophotographic images. 
     The apparatus main body A further includes a pickup roller  5   a , a pair of feeding rollers  5   b , a transfer guide  6 , a transfer roller  7 , a conveyance guide  8 , a fixing apparatus  9 , a pair of discharge rollers  10 , and a discharge tray  11 , which are arranged along the conveying direction D of the sheet material PA. The fixing apparatus  9  includes a heating roller  9   a  and a pressing roller  9   b.    
     Image Formation Process 
     The outline of the image formation process is now described. In response to a print start signal, the electrophotographic photosensitive drum (hereinafter, referred to as photosensitive drum  62  or simply as drum  62 ) is driven to rotate in the arrow R direction at a predetermined circumferential speed (process speed). A charging roller (charging member)  66 , to which a bias voltage is applied, is in contact with the outer circumferential surface of the drum  62  and uniformly charges the outer circumferential surface of the drum  62  (see  FIG. 3 ). 
     The exposure apparatus  3  outputs a laser beam L according to image information. The laser beam L passes through the laser opening  71   h  provided in a cleaning frame  71  of the cartridge B, and scans the outer circumferential surface of the drum  62  to perform exposure. An electrostatic latent image corresponding to the image information is thus formed on the outer circumferential surface of the drum  62 . 
     As shown in  FIG. 3 , a developing unit  20 , which serves as the developing apparatus, includes a toner chamber  29  storing toner T. A conveyance member (agitation member)  43  rotates to agitate and convey the toner T to a toner supply chamber  28 . The magnetic force of a magnet roller  34  (stationary magnet) holds the toner T on the surface of a developing roller  32 . The developing roller  32  is a developer carrying member that carries developer (toner T) on its surface to develop the latent image formed on the drum  62 . A developing blade  42  friction-charges the toner T and controls the layer thickness of the toner T on the circumferential surface of the developing roller  32 , which serves as the developer carrying member. 
     The toner T is supplied to the drum  62  according to the electrostatic latent image to develop the latent image. As a result, the latent image is formed as a visible toner image. The drum  62  is an image bearing member that bears a latent image or an image to be formed with toner (toner image, developer image) on its surface. As shown in  FIG. 2 , the sheet material PA stored in a lower portion of the apparatus main body A is sent out from the sheet tray  4  by the pickup roller  5   a  and the pair of feeding rollers  5   b  in time with the output of a laser beam L. The sheet material PA is conveyed along the transfer guide  6  to the transfer position between the drum  62  and the transfer roller  7 . At this transfer position, the toner image is sequentially transferred from the drum  62  to the sheet material PA. 
     The sheet material PA to which the toner image is transferred is conveyed away from the drum  62  and to the fixing apparatus  9  along the conveyance guide  8 . The sheet material PA then passes through the nip portion of the heating roller  9   a  and the pressing roller  9   b  of the fixing apparatus  9 . The fixing process of pressing and heating at the nip portion fixes the toner image on the sheet material PA. The sheet material PA that has undergone the toner image fixing process is conveyed to the pair of discharge rollers  10  and discharged to the discharge tray  11 . 
     As shown in  FIG. 3 , the residual toner on the outer circumferential surface of the drum  62  after transferring is removed by a cleaning member  77  and used for an image formation process again. The toner removed from the drum  62  is stored in a waste toner chamber  71   b  of a cleaning unit  60 . The cleaning unit  60  is a photosensitive drum unit including the photosensitive drum  62 . 
     In the foregoing description, the charging roller  66 , the developing roller  32 , the transfer roller  7 , and the cleaning member  77  function as a process unit for acting on the drum  62 . 
     Overall Cartridge Configuration 
     Referring to  FIGS. 3, 4, and 5 , the overall configuration of the cartridge B is now described.  FIG. 3  is a cross-sectional view of the cartridge B, and  FIGS. 4 and 5  are perspective views illustrating the configuration of the cartridge B. In this embodiment, the description of the screws for connecting parts is omitted. 
     The cartridge B includes the cleaning unit (photosensitive member holding unit, drum holding unit, image bearing member holding unit, first unit)  60  and the developing unit (developer carrying member holding unit, second unit)  20 . 
     As shown in  FIG. 3 , the cleaning unit  60  includes the drum  62 , the charging roller  66 , the cleaning member  77 , and a cleaning frame  71 , which supports these components. On the drive side, the drum  62  includes a drive-side drum flange  63 , which is rotationally supported by a hole portion  73   a  of a drum bearing  73  (see  FIG. 4 ). In a broad sense, the drum bearing  73  and the cleaning frame  71  can be collectively referred to as a cleaning frame. 
     As shown in  FIG. 5 , on the non-drive side, a drum shaft  78  is press-fitted into a hole portion  71   c  formed in the cleaning frame  71  so that a hole portion (not shown) of the non-drive-side drum flange is rotationally supported. The drum flanges are portions that are rotationally borne and supported by the respective bearing portions. 
     As shown in  FIG. 3 , the charging roller  66  and the cleaning member  77  of the cleaning unit  60  are in contact with the outer circumferential surface of the drum  62 . 
     The cleaning member  77  has a rubber blade  77   a , which is a blade-shaped elastic member made of rubber as an elastic material, and a support member  77   b  supporting the rubber blade. The rubber blade  77   a  substantially extends in the direction opposite to the rotation direction of the drum  62  and is in contact with the drum  62 . That is, the rubber blade  77   a  is in contact with the drum  62  with its distal edge portion pointing toward the upstream side in the rotation direction R of the drum  62 . The waste toner removed from the surface of the drum  62  by the cleaning member  77  is stored in the waste toner chamber  71   b  defined by the cleaning frame  71  and the cleaning member  77 . 
     As shown in  FIG. 3 , a scooping sheet  65  for preventing waste toner from leaking from the cleaning frame  71  is provided at an edge of the cleaning frame  71  in contact with the drum  62 . 
     The charging roller  66  is rotationally attached to the cleaning unit  60  through charging roller bearings  67  located at opposite ends in the longitudinal direction of the cleaning frame  71 . The longitudinal direction of the cleaning frame  71  (the longitudinal direction of the cartridge B) is substantially parallel to the direction in which the rotation axis of the drum  62  extends (axial direction). Hereinafter, the longitudinal direction and the axial direction therefore refer to the axial direction of the drum  62  unless otherwise specified. 
     Urging members  68  press the charging roller bearings  67  toward the drum  62 , thereby pressing the charging roller  66  against the drum  62 . The charging roller  66  is driven and rotated by the rotation of the drum  62 . 
     As shown in  FIG. 3 , the developing unit  20  includes the developing roller  32 , a developing container  600  supporting the developing roller  32 , and a developing blade  42 . The developing roller  32  is rotationally attached to the developing container  600  through bearing members  26  ( FIG. 4 ) and  27  ( FIG. 5 ) provided at opposite ends. 
     The developing roller  32  contains the magnet roller  34 . The developing unit  20  includes the developing blade  42  for controlling the toner layer on the developing roller  32 . As shown in  FIGS. 4 and 5 , spacing members  38  are attached to opposite ends of the developing roller  32 . The spacing members  38  are brought into contact with the drum  62 , so that the developing roller  32  is held with a small gap created between the developing roller  32  and the drum  62 . As shown in  FIG. 3 , a spout prevention sheet  33  for preventing the toner from leaking from the developing unit  20  is provided at an edge of the developing container  600  and in contact with the developing roller  32 . A conveyance member  43  is provided in the toner chamber  29  defined by the developing container  600  and a lid  601 . The conveyance member  43  agitates the toner stored in the toner chamber  29  and conveys the toner to the toner supply chamber  28 . 
     As shown in  FIGS. 4 and 5 , the cartridge B is formed by combining the cleaning unit  60  and the developing unit  20 . To join the developing unit  20  to the cleaning unit  60 , the center of a first developing-side support boss  26   a  of the bearing member  26  is aligned with a first suspension hole  71   i  on the drive side of the cleaning frame  71 , and the center of a second developing-side support boss  27   a  of the bearing member  27  is aligned with a second suspension hole  71   j  on the non-drive side. Specifically, the developing unit  20  is moved in the direction of arrow G so that the first and second developing-side support bosses  26   a  and  27   a  are fitted into the first and second suspension holes  71   i  and  71   j . The developing unit  20  is thus movably connected to the cleaning unit  60 . Specifically, the developing unit  20  is rotationally (pivotally) connected to the cleaning unit  60 . That is, the developing roller  32  is coupled to the drum  62  so as to be movable toward and away from the drum  62 . Then, the drum bearing  73  is coupled to the cleaning unit  60  to form the cartridge B. 
     In this embodiment, a non-drive-side urging member  46 L ( FIG. 5 ) and a drive-side urging member  46 R ( FIG. 4 ) are compression springs. The urging force of the springs allows the drive-side urging member  46 R and the non-drive-side urging member  46 L to urge the developing unit  20  to the cleaning unit  60 , ensuring that the developing roller  32  is pressed in the direction of the drum  62 . The present embodiment also includes the spacing members  38  at opposite ends of the developing roller  32 . That is, the drum  62  is in contact with the developing roller  32  through the spacing members  38  with a predetermined contact pressure, so that the developing roller  32  is held with a predetermined gap created between the developing roller  32  and the drum  62 . The relative positions of these components are thus determined. 
     Cartridge Attachment 
     Referring to  FIGS. 6A, 6B, 7A, and 7B , the attachment of the cartridge B is now described in detail.  FIG. 6A  is a cross-sectional view of the drive-side guide portion of the image forming apparatus A for illustrating the attachment of the cartridge B.  FIG. 6B  is a cross-sectional view of the non-drive-side guide portion of the image forming apparatus A for illustrating the attachment of the cartridge B.  FIG. 7A  is a cross-sectional view of the drive side of the image forming apparatus A for illustrating the positioning of the cartridge B.  FIG. 7B  is a cross-sectional view of the non-drive side of the image forming apparatus A for illustrating the positioning of the cartridge B. 
     The cartridge B is attached as follows. As shown in  FIGS. 6A and 6B , a first drive-side plate  15  includes an upper guide rail  15   g  and a guide rail  15   h  as guides, and a non-drive-side plate  16  includes a guide rail  16   d  and a guide rail  16   e . The drum bearing  73  provided on the drive side of the cartridge B has a rotation stop target portion  73   c . The cartridge B is attached in a direction (arrow C) substantially perpendicular to the axis of the drum  62  ( FIG. 3 ). 
     The cleaning frame  71  includes, on the non-drive side in the longitudinal direction, a positioning target portion  71   d  as a first positioning portion and a rotation stop target portion  71   f  as a second positioning portion. When the cartridge B is attached through a cartridge insertion slot  17  of the apparatus main body A, the guide rail  15   h  of the apparatus main body A guides the rotation stop target portion  73   c  of the cartridge B on the drive side of the cartridge B. On the non-drive side of the cartridge B, the guide rails  16   d  and  16   e  of the apparatus main body A guide the positioning target portion  71   d  and the rotation stop target portion  71   f  of the cartridge B. The cartridge B is thus attached to the apparatus main body A. 
     The closing of an opening/closing door  13  is now described. As shown in  FIGS. 6A, 6B, 7A, and 7B , the first drive-side plate  15  has an upper positioning portion  15   a , a lower positioning portion  15   b , and a rotation stop portion  15   c  as positioning portions, and the non-drive-side plate  16  has a positioning portion  16   a  and a rotation stop portion  16   c . The drum bearing  73  includes a positioning target portion (first positioning target portion, first protrusion, first bulging portion)  73   d  and a positioning target portion (second positioning target portion, second protrusion, second bulging portion)  73   f.    
     Cartridge pressing members  1  and  2  are rotationally attached to opposite axial ends of the opening/closing door  13 . Cartridge pressing springs  19  and  21  are attached to the longitudinal ends of the front plate of the image forming apparatus A. The drum bearing  73  has a pressing target portion  73   e  as an urging force receiving portion, and the cleaning frame  71  has a pressing target portion  710  on the non-drive side (see  FIG. 3 ). When the opening/closing door  13  is closed, the cartridge pressing members  1  and  2  urged by the cartridge pressing springs  19  and  21  of the apparatus main body A press the pressing target portions  73   e  and  710  of the cartridge B (see  FIGS. 7A and 7B ). 
     As a result, on the drive side, the upper positioning target portion  73   d , the lower positioning target portion  73   f , and the rotation stop target portion  73   c  of the cartridge B are fixed to the upper positioning portion  15   a , the lower positioning portion  15   b , and the rotation stop portion  15   c , respectively, of the apparatus main body A. The cartridge B and the drum  62  are thus positioned on the drive side. Likewise, on the non-drive side, the positioning target portion  71   d  and the rotation stop target portion  71   f  of the cartridge B are fixed to the positioning portion  16   a  and the rotation stop portion  16   c , respectively, of the apparatus main body A. The cartridge B and the drum  62  are thus positioned on the non-drive side. 
     The above description of an example of the configuration for positioning the cartridge B relative to the apparatus main body A is not intended to limit the means for positioning. A configuration may be used that directly acts on the positioning target portion  73   d  and the rotation stop target portion  73   f  on the drive side of the cartridge B, and the positioning target portion  71   d  and the rotation stop target portion  71   f  on the non-drive side to fix the positioning portions. 
     Referring to  FIGS. 8A, 8B, 8C, and 8D , the configuration in which the cartridge B receives driving force from the apparatus main body A is now described.  FIG. 8A  is a diagram showing the configuration of a drive portion of the apparatus main body A.  FIG. 8B  is a diagram showing the configuration of a drive portion of the cartridge B.  FIG. 8C  is a diagram showing a state before the drive portions of the apparatus main body A and the cartridge B are engaged.  FIG. 8D  is a diagram showing a state in which the power of the apparatus main body A is turned on and the drive portions of the apparatus main body A and the cartridge B are engaged. 
     As shown in  FIG. 8A , the apparatus main body A includes a drive transmission member  81 , which receives driving force from a driving source (not shown) of the apparatus main body A and transmits the driving force to the cartridge B. As shown in  FIG. 8B , the cartridge B includes a driven portion  63   b  in the drive-side drum flange  63  to engage with the drive transmission member  81  and receive the driving force. When the opening/closing door  13  is closed and the power of the apparatus main body A is turned on, the drive transmission member  81  moves in the direction of arrow E in  FIG. 8C . Then, as shown in  FIG. 8D , a drive transmission portion  81   b  of the drive transmission member  81  engages with the driven portion  63   b  of the drive-side drum flange  63 , and the drum  62  is rotated through the drive-side drum flange  63 . The outer circumference of the drive transmission member  81  has a gear shape  81   g . Additionally, a developing roller gear  90  is coupled to an end of the developing roller  32  of the cartridge B. When the driven portion  63   b  of the drive-side drum flange  63  is engaged as shown in  FIG. 8D , the gear shape  81   g  on the drive transmission member  81  and the developing roller gear  90  are arranged so as to mesh with each other. That is, when the drive transmission member  81  rotates the drum  62  through the drive-side drum flange, the developing roller  32  also rotates simultaneously through the developing roller gear  90 . 
     Configuration of Developing Unit  20   
     Referring to  FIG. 9 , the configuration of the developing unit  20  is described in further detail.  FIG. 9  is a perspective view illustrating the configuration of the developing unit  20 . 
     As shown in  FIG. 9 , the developing container  600  is integrally joined, at a first opening  600   a , with the lid  601 , which is a first base member, by a joining member such as welding. The conveyance member  43  includes a shaft member  43   a  (support member) and a conveyance sheet member  43   b  (sheet) as a sheet member. The conveyance sheet member  43   b , which is a flexible member, is fixed to the shaft member  43   a  by a fixing member such as snap fit, heat caulking, or double-sided tape. That is, the shaft member  43   a  supports the conveyance sheet member  43   b . The shaft member  43   a  includes a drive opening  43   a   1  for driving input from the outside and a cylindrical supported portion (not shown). When the developing container  600  and the lid  601  are joined, the conveyance member  43  is placed within the developing container  600  and supported so as to be rotatable about a rotation axis A 1  (rotation axis) and relative to the developing container  600 . The lid  601  is located opposite to the developing roller  32  with respect to the conveyance member  43 . As such, the capacity of the developing unit  20  can be changed simply by replacing the lid  601  with a smaller second base member  602  (see  FIG. 13 ). This allows the assembly steps to be easily changed when the capacity of the developing container  600  varies among production lots. When the conveyance member  43  rotates about the rotation axis A 1  of the conveyance member  43  and if the conveyance sheet member  43   b  maintains its natural state (natural length), the circle that is traced by the sheet distal edge portion  43   b   1  of the conveyance member  43  is referred to as a rotation path  43   r  of the conveyance member  43  (see  FIG. 1 ). The “natural length” used herein refers to the distance (first distance) between the rotation axis A 1  of the shaft member  43   a  and an edge of the conveyance sheet member  43   b  in a direction perpendicular to the rotation axis A 1  in a state in which the conveyance sheet member  43   b  is unbent. That is, the circle (rotation path  43   r ) that is traced by the sheet distal edge portion  43   b   1  is an imaginary circle having a center on the rotation axis A 1  and a radius of the first distance. 
     The drive-side end of the shaft member  43   a  has the drive opening  43   a   1 , which faces the developing container  600 . The developing container  600  has a hole  600   n  (see  FIG. 9 ), which faces the drive opening  43   a   1 . A conveyance gear  93  is inserted into the hole  600   n  from the outer side in the longitudinal direction of the developing container  600  and engages with the drive opening  43   a   1  inside the developing container  600 . The conveyance gear  93  is connected to the developing roller gear  90  by a first idler gear  91  and a second idler gear  92  so as to be driven. The drive transmission member  81  drives the developing roller gear  90  to rotate the conveyance gear  93 . The rotation of the conveyance gear  93  rotates the conveyance member  43 . A conveyance sealing member  94  is compressed between the conveyance gear  93  and the developing container  600 . The conveyance sealing member  94  is made of a material with sufficient cushioning characteristics and adhesiveness, such as urethane foam. The conveyance sealing member  94  is in close contact with the conveyance gear  93  and the developing container  600 , thereby preventing the toner in the developing container  600  from leaking to the outside through the hole  600   n.    
     Description of Developing Frame 
     Referring to  FIGS. 1, 10, and 11 , the configuration of the developing unit  20  is described in further detail.  FIG. 1  is a cross-sectional view of the principal section of the developing unit  20  including the developing container  600 . As shown in  FIG. 1 , the developing unit  20  stores toner T in the storage space defined by the developing container  600  and the lid  601 .  FIG. 10  is a cross-sectional view illustrating the support configuration of the conveyance member  43 .  FIG. 11  is a partial cross-sectional view of the drive-side end of the developing unit  20  as viewed from the non-drive side in the longitudinal direction. 
     As shown in  FIG. 1 , a developer sealing wall  600   b  divides the developing container  600  into a developing portion  600   c  and a developer storage portion  600   d . The developer storage portion  600   d  includes the above-mentioned conveyance member  43 , and is formed by the developer sealing wall  600   b , an upper wall  600   e , a first opening  600   a , and a lower wall  600   g . The developer sealing wall  600   b  has a second opening  600   h , which provides communication between the developer storage portion  600   d  and the developing portion  600   c . The conveyance member  43  conveys toner T to the developing portion  600   c  through the second opening  600   h . The section of the developer sealing wall  600   b  located below the second opening  600   h  is referred to as a lower sealing wall  600   b   1 , and the section above the second opening  600   h  is referred to as an upper sealing wall  600   b   2 . 
     The developing portion  600   c  includes the developing roller  32 , the developing blade  42 , a developing blade back seal  600   j , and a developing roller lower sheet  602 . The developing roller  32  faces the second opening  600   h . That is, the conveyance member  43  conveys the toner T toward the developing roller  32  through the second opening  600   h . This configuration allows the toner T conveyed to the developing portion  600   c  to be carried on the developing roller  32  with a constant layer thickness as the developing roller  32  rotates. Additionally, the configuration limits leakage of the toner T from the developing portion  600   c . An inclined portion  600   k  is formed between the second opening  600   h  and the developing roller  32 . The inclined portion  600   k  is continuous with the lower sealing wall  600   b   1 . The developing blade back seal  600   j  and the inclined portion  600   k  are parts of the developing container  600 , while the developing blade  42  and the developing roller lower sheet  602  are directly fixed to the developing container  600  (not shown). 
     The lid  601  is fixed to the developing container  600  at the first opening  600   a  of the developing container  600 . The lid  601  includes an upper wall  601   a , a first inclined surface  601   b , a second inclined surface  601   c , and a concave arcuate wall  601   d  (arcuate surface). The first and second inclined surfaces  601   b  and  601   c  each form, with a horizontal plane, an angle that allows the toner T to fall under its own weight (the angle of repose) or greater (an angle greater than or equal to the angle of repose). The arcuate wall  601   d  is continuous with the lower wall  600   g , which is the base surface of the developing container  600 . The lid  601  further includes ribs  601   f  extending across the upper wall  601   a  and the first and second inclined surfaces  601   b  and  601   c . The ribs  601   f  serve as contact portions configured to come into contact with the conveyance sheet member  43   b . Each rib  601   f  extends across the first and second inclined surfaces  601   b  and  601   c  and along a plane perpendicular to the rotation axis. The ribs  601   f  are provided at intervals in the longitudinal direction (ribs  601   f   1  to  601   f   3 , see  FIG. 9 ). 
     The relationship between the above-mentioned components and the rotation path  43   r  of the conveyance member  43  is now described. As shown in  FIG. 1 , a part of the inclined portion  600   k  in the developing portion  600   c  is at the inner side of the rotation path  43   r . The inclined portion  600   k  faces toward the rotation center A 1  of the conveyance member  43 . The inclined portion  600   k  is an inclined surface extending from the lower edge of the second opening  600   h  such that the distance from the rotation center A 1  (rotation axis) of the conveyance member  43  gradually increases from the upstream side to the downstream side in the rotation direction S of the conveyance member  43 . The lid  601  includes a region (corner portion  601   g ) that extends the toner storage space outward of the rotation path  43   r . Of the space defined by the upper wall  601   a , the first inclined surface  601   b , and the second inclined surface  601   c , the corner portion  601   g  defines a space that is outside the rotation path  43   r . The ribs  601   f  located in this corner portion  601   g  each have the shape of a rib protruding to the inner side of the rotation path  43   r . Each rib  601   f  is formed so that the distance from the rotation center A 1  increases from the upstream side to the downstream side in the rotation direction S. 
     According to the configuration described above, the inclined portion  600   k  faces toward the rotation center A 1 , and the distance between the inclined portion  600   k  and the rotation center A 1  increases in the rotation direction S. Consequently, the conveyance sheet member  43   b  is gradually released from bending while in contact with the inclined portion  600   k  (see also  FIG. 10 ). The allows the toner T on the inclined portion  600   k  to be conveyed in the direction of the developing roller  32 , achieving the efficient use of the toner T in the developing portion  600   c . Also, the bending of the conveyance sheet member  43   b  is released gradually, reducing the noise (release noise) generated when the conveyance sheet member  43   b  is released from a bent state. 
     Furthermore, the lid  601  includes the corner portion  601   g , which is outside the rotation path  43   r , allowing the toner T to be stored outward of the rotation path  43   r . The developing unit  20  can thus have a larger capacity. 
     Moreover, the ribs  601   f , which protrude into the inner side of the rotation path  43   r , are located in the corner portion  601   g . As such, the conveyance member  43  rotates with its distal edge portion  43   b   1  constantly in contact with the developing container  600  or the lid  601  except when the distal edge portion  43   b   1  reaches the developing portion  600   c  (see also  FIG. 11 ). This reduces the occasions in which the conveyance sheet member  43   b  is released from a bent state, thereby reducing the release noise. The configuration also reduces the fatigue fracture, which would otherwise occur due to repeated bending and releasing of the conveyance sheet member  43   b.    
     Each rib  601   f  is shaped such that the distance from the rotation center A 1  increases in the rotation direction S. As such, when the conveyance sheet member  43   b  moves from the upper wall  600   e  and along the ribs  601   f , the bending of the conveyance sheet member  43   b  is gradually released without fluctuations. This reduces the occasions in which the conveyance sheet member  43   b  is released, further limiting the generation of release noise and fatigue fracture. The ribs  601   f  are located in a region having an angle greater than or equal to the angle of repose in the inner surface of the corner portion  601   g  forming the storage space. The arcuate wall  601   d , which has an angle less than the angle of repose, does not have a rib. This allows the conveyance sheet member  43   b  to come into contact with the arcuate wall  601   d  and thus convey the toner T on the arcuate wall  601   d.    
     Other Embodiments 
     As shown in  FIG. 12 , the conveyance member  43  may include a second sheet member  43   c , which may be fixed to the developer sealing wall  600   b  by heat welding or other means. The second sheet member  43   c  may be fixed to the developer sealing wall  600   b  with a fixing force that allows the second sheet member  43   c  to be peeled off from the developer sealing wall  600   b  when the conveyance member  43  rotates at the beginning of use of the cartridge B, thereby opening the second opening  600   h . As such, when the cartridge B is unused, the developer sealing wall  600   b  and the second sheet member  43   c  separate the developer storage portion  600   d  from the developing portion  600   c  to prevent leakage of the toner T during its distribution and storage. 
       FIG. 13  shows another embodiment in which the lid  601  is replaced with a second base member  603  including ribs  603   f  that extend along planes perpendicular to the rotation axis of the conveyance member  43  and are configured to come in contact with the conveyance sheet member  43   b  as contact portions. The second base member is shaped so that the inner surface defining the toner storage space is located inside the rotation path of the conveyance member  43 . As such, the amount of toner T stored in the developing unit  20  can be changed. Each rib  603   f  is shaped such that the distance from the rotation center A 1  gradually increases from the upstream side to the downstream side in the rotation direction S, thereby reducing the occasions in which the conveyance sheet member  43   b  is released. 
     This embodiment reduces the fatigue of the conveyance sheet member  43   b  in the developing apparatus whose storage capacity for developer can be changed simply by replacing the base member. This embodiment also reduces the release noise of the conveyance sheet member  43   b . Furthermore, the toner T in the developing portion  600   c  is used efficiently. 
     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. 2020-102663, filed on Jun. 12, 2020, which is hereby incorporated by reference herein in its entirety.