Abstract:
A developing apparatus for developing operation on an image bearing member, includes a rotatable developer carrying member for carrying a developer; a rubbing member for rubbing the developer carrying member with the developer therebetween to cause the developer to be carried on the developer carrying member; wherein the rubbing member includes a free end portion extending toward a downstream with respect to a rotational moving direction of the developer carrying member, the free end portion rubs the developer carrying member, and wherein the rubbing member is provided with a reinforcing portion for reinforcing the free end portion.

Description:
FIELD OF THE INVENTION AND RELATED ART 
       [0001]    The present invention relates to image forming apparatuses, such as copying machine, printers, etc., which are provided with a function for forming an image on a sheet of recording medium. In particular it relates to a developing device and a process cartridge with which these image forming apparatuses are provided. 
         [0002]    It has been known that some conventional developing devices are configured as follows: They are made up of a development roller, a supply roller, a regulating member, a toner container and so on. The development roller bears developer, and develops an electrostatic latent image formed on a photosensitive member. The regulating member regulates in thickness the layer of developer on the development roller. The toner container stores toner (Japanese Laid-open Patent Application H06-301281). 
         [0003]    The supply roller is placed in contact with the development roller in such a manner that it is compressed by a preset amount by the development roller. It rotates in the same direction as the development roller. Conventionally, a sponge roller made up of a metallic core, and a layer of sponge which covers the peripheral surface of the metallic core is used as the supply roller. In a case where a sponge roller is used as the supply roller, developer is taken up by the sponge layer of the sponge roller, and is conveyed to the area of contact, between the development roller and sponge roller, in which the sponge layer of the sponge roller is compressed by the development roller. Consequently, the developer in the sponge layer is discharged, being thereby supplied to the development roller. 
         [0004]    In recent years, users of an image forming apparatus have become increasingly concerned with the environment. Thus, it has become important to use the developer in a toner container as completely as possible. However, there has been a concern that in the case of the conventional configuration for a developing device, the developer in the portion of the sponge layer which is in the adjacencies of the metallic core of the sponge roller will fail to be discharged from the sponge layer to be supplied to the development roller. In order to reduce the sponge roller in the amount by which the developer fails to be delivered from the development roller to be used for development, it is necessary not to use the sponge roller to supply the development roller with developer. 
         [0005]    The present invention was made in consideration of an issue such as the above-described one. Thus, the primary object of the present invention is to increase a developer supply roller in the ratio with which the developer in the roller can be discharged to be used for development. 
       SUMMARY OF THE INVENTION 
       [0006]    According to an aspect of the present invention, there is provided a developing apparatus for developing operation on an image bearing member, comprising a rotatable developer carrying member for carrying a developer; a rubbing member for rubbing said developer carrying member with the developer therebetween to cause the developer to be carried on said developer carrying member; wherein said rubbing member includes a free end portion extending toward a downstream with respect to a rotational moving direction of said developer carrying member, said free end portion rubs said developer carrying member, and wherein said rubbing member is provided with a reinforcing portion for reinforcing the free end portion. 
         [0007]    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 
         [0008]      FIG. 1  is a schematic sectional view of the developing device in the first embodiment of the present invention. It is for describing the structure of the developing device. 
           [0009]      FIG. 2  is a schematic sectional view of the image forming apparatus in the first embodiment. 
           [0010]      FIG. 3  is a schematic sectional view of the image forming apparatus in the first embodiment. 
           [0011]      FIG. 4  is a schematic drawing for describing the toner movement in the adjacencies of the nip between the toner supplying member and development roller, in the first embodiment. 
           [0012]      FIG. 5  is a schematic drawing for showing the toner movement in the nip between the toner supplying member and development roller, in a case where a wedge-shaped portion is present. 
           [0013]      FIG. 6  is a schematic sectional view of the developing device in the second embodiment of the present invention, and is for describing the structure of the developing device. 
           [0014]      FIG. 7  is a schematic sectional view of the developing device in the third embodiment of the present invention, and is for describing the structure of the developing device. 
           [0015]      FIG. 8  is a schematic drawing for describing the toner movement in the adjacencies of the nip between the toner supplying member and development roller. 
           [0016]      FIG. 9  is a schematic drawing for describing the toner movement in the adjacencies of the nip between the toner supplying member and development roller, in the third embodiment, in a case where the angle θ is an acute angle. 
           [0017]      FIG. 10  is a schematic drawing of a combination of the toner supplying member and development roller in one of the modifications of the preceding embodiment, and is for describing the configuration of the developing device. 
           [0018]      FIG. 11  is a schematic drawing of a combination of the toner supplying member and development roller in another modification of the preceding embodiments, and is for showing the configuration of the developing device. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    Hereinafter, a few of the preferred embodiments of the present invention are described with reference to the appended drawings. However, the measurements, materials, and shapes of the structural components of the developing device, and the positional relationship among the structural components, in the following embodiments of the present invention, are not intended to limit the present invention in these properties. That is, they are to be modified as necessary according to the configuration of the device to which the present invention is applied, and also, according to the condition under which the device is used. The present invention relates to a developing apparatus employed by an electrophotographic apparatus, an electrostatic recording apparatus, and the like to develop an electrostatic latent image (into visible image), with the use of developer. 
       Embodiment 1 
       [0020]    Next, the first embodiment of the present invention is described. 
       &lt;Image Forming Apparatus&gt; 
       [0021]      FIGS. 2 and 3  are schematic sectional views of the image forming apparatus in this embodiment, at a plane perpendicular to the rotational axis of the photosensitive drum  1  (development roller  25 ). Referring to  FIG. 2 , the image forming apparatus is provided with a photosensitive drum  1 , as an image bearing member, which is rotatable in the direction indicated by an arrow mark R 1 . The image forming apparatus is also provided with a charge roller  2 , a developing device (development unit)  5 , a transfer roller  6 , and a cleaning device  9 , which are disposed in the listed order in terms of the direction indicated by the arrow mark R 1  in  FIG. 2 . Further, the image forming apparatus is provided with an exposing device  3 , which forms an electrostatic latent image on the peripheral surface of the photosensitive drum  1  by emitting a beam of laser light in such a manner that the beam is projected upon points of exposure (which are on downstream side of charge roller  2  and upstream side of developing device  5 ) on the photosensitive drum  1 , by way of a deflection mirror  4 . 
         [0022]    With the image forming apparatus being structured as described above, as the photosensitive drum  1  is rotated, the charging, exposing, developing, and cleaning processes are sequentially carried out for numerous points of the peripheral surface of the photosensitive drum  1  (detailed description of these processes is given later). 
         [0023]    The charge roller  2  is for uniformly charging the peripheral surface of the photosensitive drum  1 . The developing device  5  is for storing non-magnetic single-component toner T, and developing an electrostatic latent image formed on the peripheral surface of the photosensitive drum  1  (puts photosensitive drum  1  through development process), into a toner image (visible image formed of toner). 
         [0024]    Referring to  FIG. 3 , the developing device  5  is structured so that it can be removably installable in the main assembly of the image forming apparatus. That is, the developing device  5  may be placed in a cartridge which is removably mountable in the main assembly of the image forming apparatus. The transfer roller  6  is for transferring a toner image formed on the peripheral surface of the photosensitive drum  1 , onto a sheet P of recording medium. The cleaning device  9  is for removing the toner which failed to be transferred onto a sheet P of recording medium, being therefore remaining on the photosensitive drum  1  after the transfer. It is provided with a cleaning blade, which is placed in contact with the peripheral surface of the photosensitive drum  1  to scrape away the toner from the peripheral surface of the photosensitive drum  1 . 
         [0025]    Further, the image forming apparatus is provided with a fixing device  15  which applies heat and pressure to the sheet P of recording medium and the toner image thereon to fix the toner image to the sheet P, after the transfer of the toner image onto the sheet P. 
       &lt;Image Forming Process&gt; 
       [0026]    Next, the image forming operation of the image forming apparatus in this embodiment is described. 
         [0027]    First, referring to  FIG. 2 , the photosensitive drum  1  is rotated in the direction indicated by an arrow mark R 1  at 100 mm/sec. As the photosensitive drum  1  is rotated, the peripheral surface of the photosensitive drum  1  is charged by the charge roller  2  to a preset potential level. Then, a beam of laser light is emitted by the exposing device  3 , while being modulated with image formation signals which correspond to color components of the image to be formed, so that the beam of laser light is projected upon the points of the photosensitive drum  1 , which correspond to the exposing position A of the image forming apparatus. Consequently, an electrostatic image is effected upon the peripheral surface of the photosensitive drum  1 . The electrostatic latent image formed on the peripheral surface of the photosensitive drum  1  is developed by the developing device  5  in the development position C shown in  FIG. 2 . Consequently, a toner image is formed on the peripheral surface of the photosensitive drum  1 . The toner image formed on the photosensitive drum  1  is transferred onto a sheet P of recording medium, by the transfer roller  6 , in the transfer position B shown in  FIG. 2 . After the transfer of the toner image onto the sheet P, the sheet P is sent to the fixing device  15 , in which the sheet P and the toner image thereon are subjected to heat and pressure. Consequently, the toner image on the sheet P becomes fixed to the sheet P. This is how an image is formed on the sheet P. 
       &lt;Developing Device&gt; 
       [0028]      FIG. 1  is a schematic sectional view of the developing device  5  in this embodiment. It is for describing the structure of the developing device  5 . Hereafter, the developing device  5  in this embodiment is described in detail. 
         [0029]    The developing device  5  is provided with a development roller  25  which is a developer bearing member, a regulation blade  27  which is a regulating member, and a toner supplying member  24  as a toner rubbing member. The developer container  21  is for storing toner. It is equivalent to a toner storage. The development roller  25  is for bearing toner T. It is positioned so that it faces the opening of the developer container  21 , which is at the bottom of the developer container  21 . The regulation blade  27  is for controlling the amount, per unit area, by which toner is allowed to remain on the peripheral surface of the development roller  25 , that is, for controlling in thickness the layer of toner on the peripheral surface of the development roller  25 . The toner supplying member  24  is positioned so that it contacts the peripheral surface of the development roller  25 . The toner supplying member  24  is described later. 
         [0030]    By being structured as described above, the developing device  5  supplies the peripheral surface of the photosensitive drum  1  with the toner in the layer of toner borne by the development roller  25  while being regulated in thickness by the regulation blade  27 . 
         [0031]    During a developing operation, the development roller  25  rotates in contact with the photosensitive drum  1 . After the completion of the developing operation, a cam  20  with which the main assembly of the image forming apparatus is provided is rotated. As the cam  20  is rotated, it presses the top portion of the developer container  21 , causing thereby the development roller  25  to be separated from the photosensitive drum  1 . After the separation of the development roller  25  from the photosensitive drum  1 , the controlling means of the main assembly of the image forming apparatus stops the rotation of the development roller  25 . The development roller  25  comprises: an electrically conductive metallic core  28 , which is 8 mm in diameter; and an electrically conductive elastic layer formed of rubber, around the metallic core  28 ; and a surface layer formed of acrylic rubber, urethane rubber, or the like, in a manner to cover the elastic layer. The development roller  25  is 13 mm in external diameter, and roughly 10 5  Ω·cm in volume resistivity. The development roller  25  is supported by the developer container  21  so that during a developing operation, it contacts the photosensitive drum  1  in a development position C, and can be rotationally driven in the direction indicated by the arrow mark R 2  shown in  FIG. 1 . During a developing operation, the development roller  25  is 160 mm/sec in peripheral velocity. 
         [0032]    The regulation blade  27  is made of a flexible sheet of stainless steel (SUS). It is attached to a supporting plate, by one of its long edge portions, in such a manner that its free long edge portion (other long edge portion) remains in contact with the peripheral surface of the development roller  25 . The supporting plate is fixed to the developer container  21 . The regulation blade  27  is disposed in such an attitude that its long edge portion by which it is held to the supporting plate is on the downstream side of its unattached (free) long edge portion which is in contact with the peripheral surface of the development roller  25 , in terms of the rotational direction (indicated by arrow mark R 2 ), and also, that the flat and smooth surface portion of the adjacencies of the unattached (free) edge portion rubs the peripheral surface of the development roller  25 , in the toner amount regulation portion, that is, an area where the toner layer on the peripheral surface of the development roller  25  is regulated in the amount per unit area. In addition, the developing device  5  is provided with a leakage prevention seal  26 , which keeps sealed the gap between the development roller  25  and developer container  21 . 
         [0033]    The toner supplying member  24 , which is one of the structural components of the developing device  5  that characterize this embodiment is a flexible sheet made of polyphenylene sulfide. It is 0.25 mm in thickness. It is fixed to the developer container  21  by one of its long edge portions in such an attitude that the other long edge portion  24   a  (which hereafter may be referred to as “free long edge portion  24   a ”) is on the downstream side of the base portion of the toner supplying member  24 , in terms of the rotational direction of the development roller  25 . In this embodiment, it is positioned so that its free long edge portion is on the downstream side of its base portion in terms of the rotational direction of the development roller  25 . 
         [0034]    The developing device  5  is structured so that the portion of the toner supplying member  24 , which includes the free long edge  24   c , and the portion  24   b  which is next to the long edge  24   c , contacts the peripheral surface of the development roller  25 , with the presence of toner between the toner supplying member  24  and the peripheral surface of the development roller  25 , in the toner supply position D (which hereafter may be referred to simply as “nip D”). With the developing device  25  being structured as described above, as the development roller  25  rotates the development roller  25  and toner supplying member  24  rub against each other in the nip D, with presence of toner between them. Further, the developing device  5  is structured so that the top surface of the body of toner in the developer container  21  will be above the level of the nip D. That is, the developer container  21  is structured so that the toner in the developer container  21  will be in the portion of the developer container  21 , which includes the area in which the development roller  25  and toner supplying member  24  rub against each other. 
       &lt;Development Process&gt; 
       [0035]    The toner stored in the developer container  21  is supplied by the toner supplying member  24  to the development roller  25 , in the nip D, so that the toner adheres to the peripheral surface of the development roller  25 . Then, the toner particles having adhered to the peripheral surface of the development roller  25  are conveyed by the rotation of the development roller  25  to the toner amount regulation position E, shown in  FIG. 1 , in which it is regulated by the regulation blade  27  so that the amount of toner per unit area of the peripheral surface of the development roller  25  becomes proper. Then, the toner particles coated on the peripheral surface of the development roller  25  are used in the development position D to develop (into visible image) the electrostatic latent image formed on the peripheral surface of the photosensitive drum  1 . The toner particles which were not used for development, and therefore, are remaining on the peripheral surface of the development roller  25  are returned to the developer container  21 . 
       &lt;Toner Supply Process&gt; 
       [0036]    Next, the method for supplying the development roller  25  with toner, with use of the toner supplying member  24 , is described. In order to supply the development roller  25  with toner, it is necessary to place electrically charged toner in contact with the development roller  25 . Thus, the developing device  5  in this embodiment is structured so that the toner supplying member  24  and development roller  25  rub against each other, with the presence of charged toner between the toner supply roller  24  and development roller  25 , in the nip D. Thus, toner particles are tumbled in the nip D, whereby they are given triboelectric charge. After being given triboelectric charge, the toner particles are adhered to the peripheral surface of the development roller  25  by the mutual attraction between the toner particles and photosensitive drum  25 . That is, the toner particles are borne on the peripheral surface of the development roller  25 . In other words, in order to ensure that the development roller  25  is reliably supplied with toner, it has to be ensured that toner is always present in the nip D between the toner supplying member  24  and development roller  25 . 
         [0037]    The inventors of the present invention discovered that it can be ensured by structuring the developing device  5  so that the “free long edge” of the toner supplying member  24  is placed in contact with the development roller  25 , that toner will be between the toner supplying member  24  and development roller  25 , in the nip D. 
         [0038]      FIG. 4  is a drawing for describing the toner movement which occurs in the adjacencies of the nip D in a case where the free long edge portion  24   a  of the toner supplying member  24 , and the portion  24   b  of the toner supplying member  24 , which is next to the free long edge  34   c  of the toner supplying member  24 , are kept in contact with each other (they are made to rub against each other). It is assumed here that the top surface of the body of toner (in developer container (top surface) is positioned higher than the level of the nip D. 
         [0039]    Toner particles which are free of electrical charge are not subjected to external electrical force, and therefore, can freely move. Therefore, in a case where the developing device  5  is structured so that the toner supplying member  24  contacts the development roller  25  by its portion  24   b  which is next to its free long edge  24   c , toner particles which are free of electrical charge instantly flow into the nip D. Then, as the development roller  25  is rotated, the toner particles are frictionally charged because of the presence of the internal pressure of the nip N. Then, they are conveyed further by the development roller  25 . As a certain amount of toner (toner particles) is conveyed out of the nip D by the development roller  25 , other toner particles which are also free of electrical charge flow into the nip D in a manner to fill the void created as the charged toner particles are moved out the nip D. 
         [0040]    That is, the development roller  25  is supplied with toner through the repetition of the above described cycle of toner particle movement. 
         [0041]      FIG. 5  is a drawing for describing the toner movement which occurs in the developer container  21 , in a case where the developing device  5  is structured so that a space  30  which is wedge-shaped in cross-section is present in the developer container  21 , on the downstream side of the nip D between the toner supplying member  24  and development roller  25 , in terms of the rotational direction of the development roller  25 . 
         [0042]    With the presence of the space  30  (which hereafter will be referred to as “wedge-shaped space  30 ”), a toner pool is created on the front side of the nip D (downstream side of nip D in terms of rotational direction of development roller  25 ). The presence of the toner pool will possibly prevent toner from flowing into the nip D. 
         [0043]    That is, in a case where the wedge-shaped space  30  is present, it is possible that the toner will be prevented from flowing into the nip D, being thereby prevented from reaching the nip D. Thus, it is possible that it will become impossible for the development roller  25  to be reliably supplied with toner. Even in a case where the wedge-shaped space  30  is present, the toner particles having flowed into the nip D are given a satisfactory amount of electrical charge. In the toner pool, however, it does not occur that toner particles are satisfactorily charged by friction. The toner particles which failed to be fully charged, fail to be conveyed by the development roller  25 , and therefore, become stagnant in the wedge-shaped space  30 . 
         [0044]    As described above, in a case where a wedge-shape space such as the one shown in  FIG. 5  is present in the developing device  5 , it is possible that toner will not reliably flow into the nip D, and therefore, the development roller  25  will not be reliably supplied with toner. 
         [0045]    As will be evident from the description of this embodiment given above, by structuring the developing device  5  so that the portion  24   b  of the toner supplying member  24 , which is next to the free long edge  24   c  of the toner supplying member  24 , is placed in contact with the development roller  25 , it is possible to supply the development roller  25  with toner, without employing a toner supply roller with which conventional developing devices are provided to supply the development roller  25  with toner, and which is provided with a sponge layer. Further, the developing device  5  in this embodiment is structured so that it does not require a sponge roller, and therefore, it does not suffer from the problem that the toner in the sponge layer cannot be moved out of the sponge layer, and therefore, remains in the sponge layer, being therefore unusable. Therefore, the developing device  5  in this embodiment can more effectively use the toner in its developer container than any developing device in accordance with the prior art. Further, the developing device  5  does not require a toner supply roller, and therefore, is less in cost than any developing device in accordance with the prior art. In other words, the present invention can provide a developing device which is less in cost than any developing device in accordance with the prior art. Further, the developing device  5  in this embodiment does not require a toner supply roller, and therefore, it is smaller than any developing device in accordance with the prior art. That is, the present invention can provide a developing device which is smaller in size than any developing device in accordance with the prior art. 
         [0046]    In this embodiment, the toner supplying member  24  was made of polyphenylene sulfide. However, this embodiment is not intended to limit the present invention in terms of the material for the toner supplying member  24 . That is, the present invention is also applicable to a developing device, the toner supplying member  24  of which is made of polyester, polyethylene terephthalate, or the like resin. Further, this embodiment is not intended to limit the present invention in terms of the thickness of the toner supplying member  24 . All that is required of a developing device in order for the device to be compatible with the present invention is that the developing device is not structured so that as the toner supplying member  24  is placed in contact with the development roller  25 , the “wedge-shaped space” in which toner will become stagnant is created between the toner supplying member  24  and development roller  25 . 
         [0047]    Further, the developing device  5  in this embodiment used non-magnetic single-component developer. However, this embodiment is not intended to limit the present invention in terms of developer choice. All that is required of developer in order for the developer to be compatible with the present invention is that as the portion  24   b  of the toner supplying member  24 , which is next to the free long edge  24   c  of the toner supplying member  24 , and the development roller  25  rub against each other, with the presence of the developer between the toner supplying member  24  and development roller  25 , the developer is borne by the development roller  25 . 
         [0048]    Further, in this embodiment, the image forming apparatus is structured so that the developing device  5  is removably installable into the main assembly of the image forming apparatus. This embodiment, however, is not intended to limit the present invention in terms of the structure of an image forming apparatus. For example, the present invention is also applicable to an image forming apparatus structured so that its developing device ( 5 ) and photosensitive drum ( 1 ) are integral parts of the process cartridge  10  which is removably installable in the main assembly of the image forming apparatus. Further, the present invention is also compatible with a process cartridge which comprises an integral combination of the developing device ( 5 ) and photosensitive drum ( 1 ), and at least one of a charge roller ( 2 ) and a cleaning device ( 9 ) which are means for processing the photosensitive drum ( 1 ). Further, the present invention is also applicable to an image forming apparatus structured so that its developing device ( 5 ) is fixed to the main assembly of the image forming apparatus, being therefore not installed into, or removed from, the main assembly by a user. 
       Embodiment 2 
       [0049]    Next, the second embodiment of the present invention is described. 
         [0050]      FIG. 6  is a schematic sectional view of the image forming apparatus in this embodiment. It shows the general structure of the apparatus. In the following description of this embodiment, only the structural components of the apparatus, which are different from the counterparts in the first embodiment, will be described. That is, the structural components of the image forming apparatus in this embodiment, which are similar to the counterparts in the first embodiment, will not be described. 
         [0051]    One of the characteristic features of this embodiment is that the toner supplying member  24  doubles as the toner leak prevention seal  26  which covers the gap between the development roller  25  and developer container  21 . 
         [0052]    In the case of an image forming apparatus structured like the image forming apparatus in the first embodiment, it is unlikely for the area between the toner supplying member  24  and leak prevention seal  26  to be used to supply the development roller  25  with toner. Thus, from the standpoint of using the toner in the developer container  21  as thoroughly as possible, the developing device is desired to be structured so that this area between the toner supplying member  24  and leak prevention seal  26  becomes as small as possible. 
         [0053]    In this embodiment, therefore, the developing device  5  is structured so that the toner supplying member  24  doubles as a leakage prevention seal to eliminate the above described area. Therefore, the developing device in this embodiment is greater in the ratio by which the developer in the developer container  21  can be actually used for development, than any developing device in accordance with the prior art. Further, because the toner supplying member  24  doubles as the leakage prevention seal, the leakage prevention seal is unnecessary. Thus, the developing device in this embodiment is smaller in size and component count than any developing device in accordance with the prior art. That is, the present invention can reduce a developing device in size and component count. 
       Embodiment 3 
       [0054]    Next, the third embodiment of the present invention is described. 
         [0055]    This embodiment is different from the above described first and second embodiments in the shape (structure) of the toner supplying member  24 . In the following description of this embodiment, a case in which the toner supplying member  24  in this embodiment is used in place of the toner supplying member  24  in the first embodiment is described. The toner supplying member  24  in this embodiment is also satisfactorily usable in place of the toner supplying member  24  in the second embodiment. In the following description of this embodiment, only the structural components of the developing device in this embodiment, which are different from the counterparts in the first and second embodiments will be described. That is, the structural components of the developing device in this embodiment, which are similar to the counterparts in the first and second embodiments will not be described. 
         [0056]      FIG. 7  is a schematic sectional view of the developing device in this embodiment. It is for describing the structure of the developing device.  FIG. 8  is a drawing for describing the toner movement which occurs in the adjacencies of the nip D, in this embodiment. 
         [0057]    A toner supply member such as the one described above is made of a thin sheet of a certain substance. Thus, it is possible that as the toner supply member is adhered to the developer container  21 , it becomes wavy. 
         [0058]    As the toner supply member becomes wavy, the nip F between the development roller  25  and toner supplying member  24  becomes nonuniform in internal pressure, which possibly makes some toner particles fail to be frictionally charged. The toner particles having failed to be charged are unlikely to be borne by the development roller  25 . It is possible, therefore, that, in terms of the lengthwise direction of the development roller  25  (direction parallel to axial line of development roller  25 ), some portions of the development roller  25  will be supplied with toner, whereas the other portions will not be supplied with toner. In other words, it is possible that the development roller  25  will become nonuniform in terms of its lengthwise direction, in the amount of toner per unit area on its peripheral surface. Therefore, it is possible that the developing device  5  will non-uniformly develop an electrostatic latent image. 
         [0059]    In this embodiment, therefore, in order to prevent the portion  24   b  of the toner supplying member  24 , which is next to the free long edge  24   c  of the toner supplying member  24 , from becoming wavy, the toner supplying member  24  is provided with a portion  24   d , as a portion for reinforcing the portion  24   b , which is perpendicularly extended from the free long edge  24   c  of the toner supplying member  24  in the opposite direction from the development roller  25 . 
         [0060]    With the provision of the toner supplying member  24  with the reinforcement portion  24   d , it is possible to increase the toner supplying member  24  in stiffness. Therefore, it is possible to prevent the problem that when the toner supplying member  24  is adhered to the developer container  21 , toner supplying member  24 , in particular, the long edge portion  24   b  of the toner supplying member  24 , becomes wavy. 
         [0061]    Next, the relationship between the reinforcement portion  24   d  of the toner supplying member  24  and the development roller  25  is described. 
         [0062]      FIG. 9  is a drawing for describing the toner movement which occurs in the developer container  21  in a case where an angle θ is acute. The angle θ is the angle between the surface  24   e  of the reinforcement portion  24   d  of the toner supplying member  24 , which is on the downstream side of the toner supplying member  24  in terms of the rotational direction of the development roller  25 , and a line L which is tangential to the development roller  25  at the point of contact between the free long edge portion  24   b  (in particular, free long edge  24   c ) of the toner supplying member  24 , and the development roller  25 . 
         [0063]    In the case where the angle θ is acute, it is possible that a toner pool such as the one in the first embodiment will be created between the surface  24   e  of the reinforcement portion  24   d  of the toner supplying member  24 , and the development roller  25 . The presence of the developer pool will possibly prevent toner from reliably flowing into the nip D, as described above. Therefore, it is possible for the development roller  25  not to be reliably supplied with toner. 
         [0064]    Therefore, in order to make the developing device  5  in this embodiment as effective as those in the first and second embodiments (toner supplying member  24  is positioned so that it contacts development roller  25  by its portion  24   b  which is next to free long edge  24   c ), it is desired that the developing device  5  is structured so that the angle θ becomes no less than 90 degrees (right or obtuse angle). 
         [0065]    As described above, according to this embodiment, the portion  24   b  of the free long edge portion  24   a  of the toner supplying member  24  is provided with the reinforcement portion  24   d  in order to increase the toner supplying member  24  in stiffness. Therefore, not only is this embodiment as effective as the first and second embodiments, but also, it offers the following effect. That is, this embodiment can prevent the problem that when the toner supplying member  24  is adhered to the developer container  21 , the toner supplying member  24  becomes wavy. Therefore, the development roller  25  is reliably supplied with toner. 
         [0066]    Also in this embodiment, the reinforcement portion  24   d  was attached, as the toner supply member reinforcing member, to the toner supplying member  24 . This embodiment, however, is not intended to limit the present invention in terms of the choice of the toner supplying member reinforcing component. That is, the present invention is compatible with any reinforcing component for a toner supplying member, as long as the reinforcing component can prevent the portion  24   b  of the free long edge portion  24   a  of the toner supply member  25  from becoming wavy. Further, this embodiment is not intended to limit the present invention in terms of where on the toner supply member  25  the reinforcement portion  24   d  is to be attached. That is, the present invention is also compatible with a reinforcement portion  24   d  which is not attached to the portion  24   b  of the free long edge portion  24   a  of the toner supplying member  24 , as long as the reinforcement portion  24   d  can prevent the toner supplying member  24  from becoming wavy. 
         [0067]    Next, referring to  FIG. 10 , the reinforcement portion  24   d  in this modified version of the this embodiment is described. In this modified version of this embodiment, the reinforcement portion  24   h  is fixed (adhered) to the free long edge portion  24   a  of the toner supplying member  24 . More specifically, the reinforcement portion  24   h  is on the opposite side of the toner supplying member  24  from the development roller  25 . That is, the reinforcement portion  24   h  is fixed to the opposite surface of the toner supplying member  24  from the development roller contacting surface of the toner supplying member  24 . The reinforcement portion  24   h  in this modified version of the third embodiment is the same in thickness and material as that in the third embodiment. This modification of the third embodiment is not intended to limit the present invention in terms of the dimension and material for the toner supplying member  24 . 
         [0068]    The reinforcement portion  24   h  was placed on the free long edge portion  24   a  of the toner supplying member  24 . Therefore, the thickness of the reinforced portion of the toner supplying member  24  is thicker than (twice as thick as) the base portion  24   i  of the toner supplying member  24 . That is, the reinforced portion ( 24   h ) is the portion of the toner supplying member  24 , which is thicker than the base portion  24   i  of the toner supplying member  24 . 
         [0069]    With the provision of the reinforcement portion  24   h , the free long edge portion  24   a  of the toner supplying member  24  is greater in stiffness, and therefore, is less likely to deform (less likely to become wavy). 
         [0070]    The following is the summary of the effects of the above described embodiments of the present invention disclosed in this patent application. 
         [0071]    That is, according to the developing device configurations disclosed in this patent application, the present invention can provide a developing device which can use a greater amount of toner in the device than any developing device in accordance with the prior art. 
         [0072]    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. 
         [0073]    This application claims priority from Japanese Patent Applications Nos. 100151/2013 and 079697/2014 filed May 10, 2013 and Apr. 8, 2014, respectively, which are hereby incorporated by reference.