Patent Publication Number: US-8971772-B2

Title: Developer transport member and developing apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority from Japanese Patent Application No. 2012-122763, filed on May 30, 2012, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a developer transport member configured to transport a developer, and a developing apparatus provided with the developer transport member. 
     2. Description of the Related Art 
     In general, a developing apparatus of an image forming apparatus such as a laser printer or the like includes a developing chamber having a supply roller and a developing roller for carrying a developer, and a developer accommodating chamber in which the developer is accommodated. In the developing apparatus of the known image forming apparatus, the developer accommodated in the developer accommodating chamber is principally transported to the developing chamber by means of a developer transport member which is provided in the developer accommodating chamber. 
     The developer transport member principally includes a rotational shaft, and a main developer transport member body having a proximal end portion fixed to the rotational shaft and configured to be rotatable together with the rotational shaft. The main developer transport member body has the forward end portion which makes sliding contact with the inner surface of the developer accommodating chamber to cause the deflective deformation (flexible deformation). The developer is released toward the developing chamber by utilizing the elastic force brought about by the restoration from the state of deflective deformation. The main developer transport member body as described above is formed of a sheet-shaped member made of resin. 
     SUMMARY OF THE INVENTION 
     However, when the main developer transport member body stops in a state of making a contact with the inner surface of the developer accommodating chamber, and the main developer transport member body is left to stand as it is while maintaining this state for a long period of time, then the main developer transport member body causes the creep deformation, and the elastic force is weakened. As a result, the transport ability of the developer transport member is lowered or deteriorated, and it becomes impossible to supply a sufficient amount of the developer to the developing chamber. In particular, in the case of such an arrangement that the developing chamber is arranged over or above the developer accommodating chamber, if the elastic force of the main developer transport member body is weakened, a problem arises such that the transport amount of the developer is greatly decreased. 
     In view of the above, an object of the present invention is to provide a developer transport member which makes it possible to suppress the decrease in the transport ability of the developer transport member and supply a sufficient amount of a developer. 
     According to a first aspect of the present teaching, there is provided a developer transport member including:
         a rotatable member;   a main body configured to transport the developer by being rotated in accordance with rotation of the rotatable member; and   a metal spring configured to bias the main body.       

     According to a second aspect of the present teaching, there is provided a developing apparatus including:
         a developer carrier configured to carry developer;   a casing defining a developer accommodating chamber for accommodating the developer and a developing chamber in which the developer carrier is arranged,   a developer transport member configured to transport the developer from the developer accommodating chamber to the developing chamber, the developing transport member including:
           a rotatable member;   a main body configured to transport the developer by being rotated in accordance with rotation of the rotatable member; and   a metal spring configured to bias the main body in a direction directed from an upstream side to a downstream side in a rotating direction when the main body is rotated while making a contact with an inner surface of the developer accommodating chamber   
               

     In any case, the metal member hardly causes the creep deformation. Therefore, even when the metal member is left to stand as it is for a long period of time in a state of being deflected or flexibly bent in the developer accommodating chamber during the stop of the developer transport member, it is possible to suppress the decrease in the transport ability of the developer transport member. Therefore, it is possible to stably supply a sufficient amount of the developer to the outside of the developer accommodating chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a sectional view illustrating a laser printer provided with an agitator according to a first embodiment. 
         FIG. 2  shows an enlarged view illustrating a developing cartridge. 
         FIG. 3A  shows an exploded perspective view illustrating the agitator according to the first embodiment, and  FIG. 3B  shows a perspective view illustrating an assembled state. 
         FIG. 4  shows an enlarged view illustrating a developing apparatus to explain the function brought about by the rotation of the agitator. 
         FIG. 5A  shows an exploded perspective view illustrating an agitator according to a second embodiment, and  FIG. 5B  shows a perspective view illustrating an assembled state. 
         FIG. 6  shows a perspective view illustrating an agitator according to a third embodiment. 
         FIG. 7  shows a perspective view illustrating an agitator according to a fourth embodiment. 
         FIGS. 8A ,  8 B and  8 C show the operation of the agitator according to the fourth embodiment. 
         FIGS. 9A and 9B  show the operation of the agitator according to the fourth embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     Next, an embodiment of the developer transport member of the present teaching will be explained in detail appropriately with reference to the drawings. In the following description, a schematic arrangement of a laser printer  1  provided with a developing apparatus according to one embodiment will be firstly explained, and then the construction concerning the feature of the present teaching will be explained. In the following description, the directions will be explained by using the directions provided on the basis of a user who uses the laser printer  1 . That is, as viewed in  FIG. 1 , the right side is defined as “front”, and the left side is defined as “rear”. The forward side is defined as “left”, and the backward side is defined as “right”. Further, the upward-downward direction, which is provided in  FIG. 1 , is defined as “up-down”. 
     [Schematic Arrangement of Laser Printer] 
     As shown in  FIG. 1 , the laser printer  1  includes, for example, in a main body casing  40 , a paper feed unit  20  configured to feed the printing paper P, and an image forming unit  30  configured to form an image on the printing paper P. Further, the laser printer  1  includes, on the main body casing  40 , a flat bed scanner  50  configured to read or scan a manuscript to generate image data. In this arrangement, the image forming unit  30  includes, for example, a process unit  60 , an exposure unit  70 , a transfer unit  80 , and a fixing unit  90 . 
     The paper feed unit  20  includes a paper feed tray  21  arranged under or below the main body casing  40 , a paper feed mechanism  22  arranged on the rear side of the paper feed tray  21 , and a printing paper pressing plate  23  configured to upwardly push or press the printing paper P accommodated in the paper feed tray  21 . The printing paper P, which is accommodated in the paper feed tray  21 , is drawn upwardly by the printing paper pressing plate  23 . The printing paper P is separated one by one by the paper feed mechanism  22 , and the printing paper P is transported upwardly. 
     The process unit  60  includes four process cartridges  62  which are accommodated in a holding case  61  and which are arranged at predetermined intervals in the front-back direction. Each of the process cartridges  62  includes a photosensitive drum  63  which has a photosensitive layer formed on the surface, an electrifier (charger)  64  configured to uniformly electrify the photosensitive layer of the photosensitive drum  63 , and a developing cartridge  10  as an example of the developing apparatus for supplying the developer to the photosensitive layer of the photosensitive drum  63 . The photosensitive drum  63  is arranged at an upper portion of the process cartridge  62 , the electrifier  64  is arranged on the rear side of the photosensitive drum  63 , and the developing cartridge  10  is arranged under or below the photosensitive drum  63 . 
     In each of the process cartridges  62 , the photosensitive layer, which is disposed on the surface of the photosensitive drum  63 , is uniformly electrified or charged by the electrifier  64 , followed by being scanned at a high speed with a laser beam radiated from the exposure unit  70  so that the photosensitive layer is exposed. As a result of the exposure of the photosensitive layer, an electrostatic latent image, which is based on the image data, is formed on the surface of the photosensitive drum  63 . A toner, which is an example of the developer, is supplied from the developing cartridge  10  to the electrostatic latent image formed on the surface of the photosensitive drum  63 . Thus, a toner image, in which the electrostatic latent image is visualized, is formed on the surface of the photosensitive drum  63 . 
     The exposure unit  70  is arranged under or below the process unit  60 , and over or above the paper feed unit  20 . The exposure unit  70  includes, for example, a laser light source (not shown), polygon mirrors, lenses, and reflecting mirrors. As for the exposure unit  70 , the laser beam, which is radiated from the laser light source, is reflected by the polygon mirror and the reflecting mirror, and the laser beam is radiated onto the surface of the photosensitive drum  63 . The laser beam is subjected to the scanning at a high speed, and thus the surface of the photosensitive drum  63  is exposed. 
     The transfer unit  80  is arranged over or above the process unit  60 . The transfer unit  80  includes a driving roller  81  arranged over or above the paper feed mechanism  22  on the rear side in the main body casing  40 , a driven roller  82  arranged on the front side in the main body casing  40 , and an intermediate transfer belt  83  configured to be wound between the driving roller  81  and the driven roller  82 . 
     The transfer unit  80  includes four primary transfer rollers  84  arranged on the inner side of a lower side pass line of the intermediate transfer belt  83  opposingly to the respective photosensitive drums  63  so that the intermediate transfer belt  83  is pressed against the four photosensitive drums  63  of the four process cartridges  62 , and a secondary transfer roller  85  arranged opposingly to the driving roller  81  so that the printing paper P is pressed against the intermediate transfer belt  83 . 
     In the transfer unit  80 , the toner images of the respective colors, which are formed on the photosensitive layers of the surfaces of the respective four photosensitive drums  63 , are successively overlaid and transferred onto the intermediate transfer belt  83 . Further, the printing paper P, which is transported upwardly from the paper feed mechanism  22 , is pressed against the intermediate transfer belt  83  by means of the secondary transfer roller  85 . Accordingly, the toner images of the respective colors, which have been overlaid and transferred onto the intermediate transfer belt, are transferred to the printing paper P. 
     The fixing unit  90  is arranged over or above the driving roller  81  of the transfer unit  80 . The fixing unit  90  includes a heating roller  91  configured to heat the printing paper P transported upwardly while being pressed by the secondary transfer roller  85 , and a pressing roller  92  arranged opposingly to the heating roller  91  so that the printing paper P is pressed against the heating roller  91 . In the fixing unit  90 , the toner images of the respective colors, which have been transferred to the printing paper P from the intermediate transfer belt  83 , are thermally fixed by being heated by the heating roller  91 . The printing paper P, on which the toner images of the respective colors have been thermally fixed, is discharged onto the paper discharge tray  41  by means of a paper discharge roller  93 . 
     [Detailed Arrangement of Developing Cartridge] 
     Next, an explanation will be made about the detailed arrangement of the developing cartridge  10 . 
     As shown in  FIG. 2  while being enlarged, the casing  13  of the developing cartridge  10  is formed with the developer accommodating chamber  11  in which the unillustrated toner is accommodated, and the developing chamber  12  arranged over or above the developer accommodating chamber  11 . An agitator  100 , which is an example of the developer transport member, is provided in the developer accommodating chamber  11 . 
     [Arrangement of Developer Accommodating Chamber] 
     An opening is formed at an upper portion of the developer accommodating chamber  11 . A lateral cross-sectional shape thereof is formed to be raindrop-shaped as shown in  FIG. 2 . A collision portion  11 A is formed at an upper portion on the rear side (left side) of the inner wall for defining the developer accommodating chamber  11 , a sliding flat surface portion  11 C is formed at an upper portion on the front side (right side) of the inner wall, and a sliding curved surface portion  11 B, which is continued to the collision portion  11 A and the sliding flat surface portion  11 C, is formed at a lower portion of the inner wall. A developer transport portion  11 D is constructed in the space between the sliding flat surface portion  11 C and the collision portion  11 A. A developer feeding port  11 E is open at an upper portion of the developer transport portion  11 D. 
     The collision portion  11 A is the wall surface against which a main agitator body  130  (main developer transport member body) of the agitator  100  is allowed to collide in the rotating direction as described later on. 
     The sliding curved surface portion  11 B is the curved surface-shaped wall surface along which the main agitator body  130  is allowed to slide while being elastically brought in contact therewith in such a state that the main agitator body  130  is elastically deformed toward the upstream side (back side in the direction of movement) in the rotating direction. 
     The sliding flat surface portion  11 C is the flat surface-shaped wall surface along which the forward end portion of the main agitator body  130  is allowed to slide while being elastically brought in contact therewith in such a state that the main agitator body  130  is elastically deformed toward the upstream side in the rotating direction. The sliding flat surface portion  11 C is inclined so that the upper portion approaches the collision portion  11 A. 
     The developer transport portion  11 D is such a space that the main agitator body  130 , which is elastically deformed toward the upstream side in the rotating direction, is rotated toward the collision portion  11 A while being elastically restored to the free state. 
     The developer feeding port  11 E is the feeding port for feeding the toner from the developer transport portion  11 D toward the developing chamber  12 . The developer feeding port  11 E is open over or above the sliding flat surface portion  11 C on the upstream side in the rotating direction of the main agitator body  130  from the collision portion  11 A. 
     [Arrangement of Developing Chamber] 
     The developing chamber  12  is arranged with a supply roller  12 A, a developing roller  12 B as an example of the developer carrier, and a layer thickness regulating blade  12 C. The developing chamber  12  is communicated with the developer accommodating chamber  11  at the developer feeding port  11 E. 
     The supply roller  12 A is the member which is provided in order that the toner adhered to the circumferential surface of the supply roller  12 A is supplied to the circumferential surface of the developing roller  12 B. The supply roller  12 A is arranged under or below the developing roller  12 B. The rotating directions of the supply roller  12 A and the developing roller  12 B are clockwise in the example shown in  FIG. 2 . On the circumferential surfaces on which the both are opposed to one another, the supply roller  12 A is moved forwardly (rightwardly), and the developing roller  12 B is moved backwardly (leftwardly) oppositely thereto. Accordingly, the toner is smoothly supplied from the circumferential surface of the supply roller  12 A to the circumferential surface of the developing roller  12 B. 
     The developing roller  12 B is the member which allows the toner supplied from the supply roller  12 A to be carried on the circumferential surface so that the toner is supplied to the electrostatic latent image formed on the circumferential surface of the photosensitive drum  63  (see  FIG. 1 ). The developing roller  12 B is arranged at the position deviated toward the front under or below the photosensitive drum  63 . 
     The layer thickness regulating blade  12 C is the member which constantly regulates the layer thickness of the toner to be carried after being supplied from the circumferential surface of the supply roller  12 A to the circumferential surface of the developing roller  12 B. The layer thickness regulating blade  12 C has the proximal end portion which is fixed to the upper portion of the backward (left) portion of the developer accommodating chamber  11  formed with the collision portion  11 A. The layer thickness regulating blade  12 C makes a contact with the lower side circumferential surface of the developing roller  12 B rotating in the backward direction (leftward direction) so that the forward end portion, which protrudes in the forward direction (rightward direction) from the proximal end portion, is opposed in the rotating direction of the developing roller  12 B. 
     [Arrangement of Agitator] 
     The agitator  100  is the part which is rotatable so that the unillustrated toner accommodated in the developer accommodating chamber  11  is agitated and transported to the developer feeding port  11 E. The agitator  100  has a rotatable member  110  extending in the left-right direction in the developer accommodating chamber  11 , a plate spring  120  as an example of the metal member, and the main agitator body  130 , proximal end portions of the plate spring  120  and the main agitator body  130  being fixed to a base portion  111  of the rotatable member  110  respectively. 
     As shown in  FIGS. 3A and 3B , the base portion  111  has an L-shaped form as viewed in a sectional view, and the base portion  111  is formed to extend in the left-right direction of the rotatable member  110 . The base portion  111  has a fixing surface  111 A which is disposed on the downstream side in the rotating direction and to which the proximal end portions of the plate spring  120  and the main agitator body  130  are fixed. 
     The plate spring  120  is formed as a plurality of plate-shaped metal pieces which are elastically deformable, and the plate spring  120  has biasing portions  121  which pushes or biases the main agitator body  130 . The proximal end portions of the plate spring  120  are fixed by pieces of double sided tape  111 B to the fixing surface  111 A of the base portion  111 . The length of the plate spring  120  ranging from the proximal end to the forward end (distal end) is set to such a length that the forward end portion of the plate spring  120  is positioned on the side of the base portion  111  (side of the rotatable member  110 ) as compared with the forward end portion of the main agitator body  130 . The forward end portions of the both are not secured to one another. That is, the forward end portion of the plate spring  120  and the forward end portion of the main agitator body  130  can be deviated from each other in the in-plane direction (surface direction) thereof. 
     The main agitator body  130  is formed as a sheet-shaped member which is formed of a resin such as polyethylene terephthalate or the like and which is capable of performing deflective deformation. The proximal end portion thereof is fixed by double sided tape  111 C to the fixing surface  111 A of the base portion  111  and the plate spring  120  fixed to the base portion  111  so that the plate spring  120 , which is fixed to the base portion  111 , is positioned on the upstream side in the rotating direction of the main agitator body  130 . The length of the main agitator body  130 , ranging from the proximal end to the forward end, is set to a length to such a degree that the forward end portion arrives at the upper portion of the collision portion  11 A confronted with the developer feeding port  11 E shown in  FIG. 2 . 
     [Detailed Explanation of Toner Transport Operation] 
     A detailed explanation will now be made with reference to  FIGS. 2 and 4  about the operation of the agitator  100 . 
     At first, as shown in  FIG. 2 , when the main agitator body  130  makes a contact with the inner surface of the developer accommodating chamber  11 , especially the sliding curved surface portion  11 B, then the plate spring  120 , arranged on the upstream side in the rotating direction of the main agitator body  130 , is elastically deformed to give such a state that the biasing portions  121  of the plate spring  120  bias the main agitator body  130  in the direction directed from the upstream side to the downstream side in the rotating direction (from the back side to the front side in the direction of movement). 
     The main agitator body  130 , which is rotated in the direction of the arrow shown in  FIG. 4 , is in the state of being deflectively deformed toward the upstream side in the rotating direction, and the forward end portion performs the rotation and the sliding movement along the sliding curved surface portion  11 B and the sliding flat surface portion  11 C of the developer accommodating chamber  11 . After that, as shown in  FIG. 4 , the main agitator body  130  releases the toner to the developer transport portion  11 D while being elastically restored to the free state in the flat plate form in the developer transport portion  11 D in accordance with the elastic restoring force of the biasing portions  121  of the plate spring  120 . The main agitator body  130  is further rotated to collide with the collision portion  11 A. Accordingly, the toner transport air flow R is generated. The released toner rides on the transport air flow R, and the toner is transported toward the developer feeding port  11 E. 
     By the way, when the agitator  100  is stopped, then the plate spring  120  and the main agitator body  130  are in the deflected postures in the developer accommodating chamber  11  (see  FIG. 2 ), and the plate spring  120  and the main agitator body  130  are left to stand as they are for a long period of time in some cases. In such a situation, for example, when the structure does not include the plate spring  120 , then the main agitator body  130  causes the creep deformation, the elastic restoring force of the main agitator body  130  is weakened, and the transport ability of the agitator  100  is lowered. 
     However, in the case of the agitator  100  of this embodiment, the toner is released to the developer transport portion  11 D by means of the elastic restoring force of the plate spring  120  formed of the metal. In other words, the plate spring  120  hardly causes the creep deformation. Therefore, even when the plate spring  120  is left to stand as it is for a long period of time in the deflected state in the stopped state of the agitator  100 , it is possible to suppress the decrease in the transport ability of the agitator  100 . Therefore, it is possible to stably supply a sufficient amount of the toner to the developing chamber  12 . 
     The plate spring  120 , which hardly causes the creep deformation, supports the main agitator body  130  from the upstream side in the rotating direction of the main agitator body  130 . Therefore, even when the rigidity and/or the elastic force of the main agitator body  130  is/are decreased, it is possible to suppress the decrease in the transport ability of the agitator  100 . Therefore, even in the case of the structure of the low cost, it is possible to stably supply a sufficient amount of the toner to the developing chamber  12 . 
     The proximal end portions of both of the plate spring  120  and the main agitator body  130  are fixed to the rotatable member  110 , and the forward end portions are not secured to one another. Therefore, the forward end portion of the plate spring  120  can be freely deviated with respect to the main agitator body  130 , and the plate spring  120  is elastically deformed with ease. Therefore, the elastic restoring force of the agitator  100  is increased, and hence the transport ability of the agitator  100  is improved. 
     The forward end portion of the plate spring  120  is positioned at the position deviated toward the rotatable member  110  as compared with the forward end portion of the main agitator body  130 . Therefore, the plate spring  120  does not make a contact with the inner surface of the developing chamber  12 . It is possible to suppress any scratch of the inner surface of the developing chamber  12 . 
     Other embodiments of the present teaching will be successively explained below. In the following respective embodiments, only portions, which are different from those of the first embodiment, will be explained. Portions, which are the same as or equivalent to those of the first embodiment, are designated by the same reference numerals, any explanation of which will be omitted. 
     Second Embodiment 
     As shown in  FIGS. 5A and 5B , an agitator  100 A of a second embodiment uses a plate spring  140  which has a plurality of biasing portions  141  and a connecting portion  142  for connecting proximal end portions of the biasing portions  141  and which is formed to have a comb-shaped form, in place of the plate spring  120  according to the first embodiment. The plate spring  140  has the connecting portion  142  which is fixed by double sided tape  111 D to the fixing surface  111 A of the base portion  111 . Further, the main agitator body  130  is fixed by double sided tape  111 E to the connecting portion  142  of the plate spring  140 . 
     According to the agitator  100 A, it is possible to stably supply a sufficient amount of the toner to the developing chamber  12  even in the case of the low cost construction, in the same manner as the first embodiment. Further, the metal member can be provided as the integrated part. Therefore, it is easy to assemble the agitator  100 A. 
     Third Embodiment 
     As shown in  FIG. 6 , an agitator  100 B of a third embodiment uses a plurality of wire springs  150 , in place of the plate spring  120  according to the first embodiment. The wire springs  150  are arranged at the same positions as those concerning the plate spring  120  according to the first embodiment. 
     According to the agitator  100 B, it is possible to stably supply a sufficient amount of the toner to the developing chamber  12  even in the case of the low cost construction, in the same manner as the first embodiment. 
     Fourth Embodiment 
     As shown in  FIG. 7 , an agitator  200  (developer transport member) of a fourth embodiment is illustrative of another exemplary embodiment, which includes a rotatable member  210 , a main agitator body  220  (main developer transport member body), and springs  230  (metal members) for connecting the rotatable member  210  and the main agitator body  220 . In the fourth embodiment, the main agitator body  220  includes a member having high rigidity, without using the member capable of performing the deflective deformation. 
     In this arrangement, the rotatable member  210  is formed to be substantially semi-cylindrical, and the rotatable member  210  has a flat surface portion  211  to which the springs  230  are attached, and a curved surface portion  212  which makes a contact with the main agitator body  220 . The main agitator body  220  is a plate-shaped member having a certain thickness. The main agitator body  220  has a transport flat plate portion  221  to which the springs  230  are attached and which is provided to transport the toner, and a displacement regulating portion  222  which is disposed on the side of the proximal end portion of the main agitator body  220  and which is formed to protrude from the surface disposed on the upstream side in the rotating direction. 
     The spring  230  is an elastically deformable spring such as a plate spring or a wire spring. The spring  230  has a deformable portion  231  which is formed to be substantially V-shaped, and fixing portions  232 ,  233  which are arranged at both ends of the deformable portion  231 . The fixing portion  232 , which is disposed on one end side of the both ends of the deformable portion  231 , is fixed to the flat surface portion  211  of the rotatable member  210 . The surface of the transport flat surface portion  221  of the main agitator body  220 , which is disposed on the proximal end portion side from the substantially central position, is fixed to the fixing portion  233  disposed on the other end side. 
     As shown in  FIGS. 8 and 9 , for example, the agitator  200  as described above is adopted for a developing cartridge  16  according to another embodiment. A casing  17  of the developing cartridge  16  constitutes a substantially cylindrical developer accommodating chamber  18  and a developing chamber  19  which is arranged on the left side of the developer accommodating chamber  18 , and an agitator  200  is provided in the developer accommodating chamber  18 . The developer accommodating chamber  18  is communicated with the developing chamber  19  via a supply port  18 A which is open at a substantially central portion on the left side as shown in the drawing. A collision portion  18 B, against which the forward end portion of the main agitator body  220  collides, is formed at the wall disposed over or above the supply port  18 A. 
     [Detailed Explanation of Toner Transport Operation] 
     An explanation will now be made in detail about the operation of the agitator  200  with reference to  FIGS. 8 and 9 . 
     At first, as shown in  FIG. 8A , when the forward end portion of the main agitator body  220  makes a contact with the inner surface of the developer accommodating chamber  18 , then the deformable portions  231  of the springs  230  are deformed, and thus the agitator  200  is in such a state that the main agitator body  220  is displaced backwardly in the rotating direction as compared with the natural state (see  FIG. 8C ). In this situation, the displacement regulating portion  222  of the main agitator body  220  makes a contact with the curved surface portion  212  of the rotatable member  210 . The agitator  200  is rotated in the developer accommodating chamber  18  while maintaining this state. 
     When the forward end portion of the main agitator body  220  arrives at the supply port  18 A in accordance with the rotation of the agitator  200  (see  FIG. 8B ), then the forward end portion of the main agitator body  220  is separated from the inner surface of the developer accommodating chamber  18 , and the main agitator body  220  is moved while performing the rotation toward the collision portion  18 B so that the main agitator body  220  springs up with respect to the rotatable member  210  in accordance with the elastic restoring force of the deformable portions  231  of the springs  230 . In this situation, a part of the toner, which is placed on the transport flat surface portion  221  of the main agitator body  220 , is supplied from the supply port  18 A to the developing chamber  19 . 
     The forward end portion of the main agitator body  220  collides with the collision portion  18 B in the rotating direction thereof (see  FIG. 8C ). Accordingly, the toner, which is placed on the transport flat surface portion  221  of the main agitator body  220 , collides with the collision portion  18 B, and the toner is supplied as it is so that the toner falls into the developing chamber  19 . 
     After that, the agitator  200  further continues the rotation, and the forward end portion of the main agitator body  220  makes a contact with the inner surface of the developer accommodating chamber  18  again. Accordingly, the deformable portions  231  of the springs  230  are deformed (see  FIG. 9A ). When the transport flat surface portion  221  of the main agitator body  220  is directed downwardly (see  FIG. 9B ), the toner, which remains on the transport flat surface portion  221  of the main agitator body  220 , is returned into the developer accommodating chamber  18 . In this way, the operation shown in  FIGS. 8 and 9  is repeatedly performed. 
     As described above, the transport force for transporting the toner, which is directed from the main agitator body  220  to the developing chamber  19 , can be generated by the springs  230  made of metal. Therefore, even when the rigidity of the main agitator body  220  is high, it is possible to transport the toner to the developing chamber  19 . 
     The embodiments of the present teaching have been explained above. However, the present teaching can be appropriately changed and carried out without being limited to the embodiments described above. 
     For example, in the first, second, and third embodiments, the sheet-shaped member, which is formed of the resin such as polyethylene terephthalate or the like, is used for the main agitator body  130 . However, it is also allowable to use a sheet-shaped member formed of any other material provided that the deflective deformation can be performed. 
     The first, second, and third embodiments are configured such that the forward end portions of the metal member and the main agitator body  130  are not secured to one another. However, the present teaching is not limited thereto. It is also allowable that the forward end portions are secured to one another. Further, for example, the plate spring and the main agitator body are fixed by means of the double sided tape. However, the present teaching is not limited thereto. It is also allowable to achieve the fixation by using any other fixing member such as an adhesive or the like. 
     The developing apparatus of each of the embodiments described above is the developing apparatus which has one developer accommodating chamber. However, the present teaching is not limited thereto. It is also allowable that the developing apparatus has a plurality of developer accommodating chambers. 
     The developing apparatus of each of the embodiments described above is constructed as the casing in which the developing chamber and the developer accommodating chamber are integrated into one unit. However, the present teaching is not limited thereto. It is also allowable that a portion, which includes the developer accommodating chamber, is constructed as a toner cartridge which is provided as a distinct member distinct from the casing. 
     In each of the embodiments described above, the developing cartridge is exemplified as the developing apparatus of the present teaching by way of example. However, the present teaching is not limited thereto. It is also allowable that a so-called process cartridge, which is provided with a photosensitive drum and a developer carrier, is provided as the developing apparatus.