Patent Publication Number: US-10310406-B2

Title: Developing device and image forming apparatus including a regulating member

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2016-171052 filed Sep. 1, 2016. 
     BACKGROUND 
     Technical Field 
     The present invention relates to a developing device and an image forming apparatus. 
     SUMMARY 
     According to an aspect of the invention, there is provided a developing device including: 
     a developer carrier that holds developer; 
     a supply member that supplies the developer to the developer carrier while agitating the developer; 
     a transport member that is disposed obliquely upward in a vertical direction of the supply member, delivers and transports the developer with agitating the developer through a passageway portion provided at each end portion in an axial direction of the supply member; and 
     a regulating member that is provided at a position corresponding to the passageway portion that delivers the developer from the supply member to the transport member, to regulate movement of the developer from the supply member to the developer carrier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a schematic configuration diagram illustrating an image forming apparatus to which a developing device according to a first exemplary embodiment of the present invention is applied; 
         FIG. 2  is a configuration diagram illustrating an image forming unit of the image forming apparatus according to the first exemplary embodiment of the present invention; 
         FIG. 3  is a schematic configuration diagram illustrating the developing device according to the first exemplary embodiment of the present invention; 
         FIG. 4  is a configuration diagram illustrating the developing device before the exemplary embodiment is applied; 
         FIG. 5  is a schematic configuration diagram illustrating an operation of the developing device according to the first exemplary embodiment of the present invention; and 
         FIG. 6  is a schematic configuration diagram illustrating an operation of the developing device according to the first exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an exemplary embodiment of the present invention will be described with reference to the drawings. 
     First Exemplary Embodiment 
       FIGS. 1 and 2  are configuration diagrams each illustrating an image forming apparatus to which a developing device according to a first exemplary embodiment of the present invention is applied.  FIG. 1  illustrates an outline of the entire image forming apparatus, and  FIG. 2  illustrates a main part (an image forming device and the like) of the image forming apparatus in an enlarged diagram. 
     &lt;Entire Configuration of Image Forming Apparatus&gt; 
     For example, an image forming apparatus  1  according to a first exemplary embodiment is configured as a monochrome printer. The image forming apparatus  1  includes an image forming unit  2  as an example of an image forming unit for forming an image on a recording medium based on image data. 
     The image forming unit  2  includes: an image forming device  10  that forms a toner image developed by a toner that constitutes developer; a transfer device  20  that transfers the toner image formed by the image forming device  10  to a recording sheet  5  as an example of a recording medium; a sheet feeding device  50  that accommodates and transports predetermined recording sheets  5  to be supplied to a transfer position T of the transfer device  20 ; and a fixing device  40  that fixes the toner image on the recording sheet  5  transferred by the transfer device  20 . Further, in  FIG. 1 , reference numeral  1   a  indicates an image forming apparatus main body, which is formed as a support structure member, or an external cover. In addition, the broken line in the drawing indicates a main transport path along which the recording sheet  5  is transported in the image forming apparatus main body  1   a.    
     The image forming device  10  includes a single image forming device that exclusively forms a toner image of black K. The image forming device  10  is disposed at a predetermined position in the vicinity of a side wall at one side (the right side in the illustrated drawings) in an internal space of the image forming apparatus main body  1   a.    
     As illustrated in  FIG. 1 , the image forming device  10  includes a photoconductor drum  11  as an example of a rotating image carrier, and the following devices are mainly disposed around the photoconductor drum  11 . The main devices include: a charging device  12  that charges a circumferential surface (an image carrying surface) of the photoconductor drum  11 , on which an image may be formed, with a predetermined electric potential; an exposure device  13  as an example of an electrostatic latent image forming unit that forms an electrostatic latent image having a potential difference by irradiating the charged circumferential surface of the photoconductor drum  11  with light LB based on information (a signal) of an image; a developing device  14  as an example of a developing unit that forms a toner image by developing the electrostatic latent image by using the toner of the developer of black K; a drum cleaning device  15  that cleans the image carrying surface of the photoconductor drum  11  by removing attached substances such as toner remaining on and attached to the image carrying surface of the photoconductor drum  11  after the transfer is performed; and the like. 
     The photoconductor drum  11  is obtained by forming an image carrying surface having a photoconductive layer (photosensitive layer) made of a photosensitive material on the circumferential surface of a cylindrical or columnar base material that is grounded. The photoconductor drum  11  is supported to be rotatable in a direction indicated by an arrow A by a power transmitted from a driving device (not illustrated). 
     The charging device  12  includes a contact charging device that includes a charging roller disposed in a state of being in contact with the photoconductor drum  11 . A charging voltage is applied to the charging device  12  by a charging high-voltage power source. In a case in which the developing device  14  performs reverse development, a voltage or electric current, which has a polarity identical to the charging polarity of the toner supplied from the developing device  14 , is supplied as the charging voltage. 
     The exposure device  13  forms an electrostatic latent image by irradiating the circumferential surface of the photoconductor drum  11  with light (a broken arrow line) LB, which is formed according to the information of an image input to the image forming apparatus  1  via a mirror  131  after the circumferential surface of the photoconductor drum  11  is charged. When a latent image is to be formed, information (signal) of an image input to the image forming apparatus  1  by an arbitrary unit is transmitted to the exposure device  13 . 
     As illustrated in  FIG. 2 , the developing device  14  is configured by disposing, within an apparatus housing (case)  140  that is formed with an opening and an accommodation chamber for developer  4 , a developing roller  141  that holds the developer  4  and transports the developer  4  to a developing region that faces the photoconductor drum  11 , a supply transport member  142  and an agitation transport member  143  such as screw augers (not illustrated) which agitate the developer  4  and transport the developer  4  so that the developer  4  passes over the developing roller  141 , a flat plate-shaped partition wall  152  that partitions an interior into a first accommodation chamber  147  that accommodates the supply transport member  142  and a second accommodation chamber  148  that accommodates the agitation transport member  143 , and a layer thickness regulating member  144  that regulates the amount (a layer thickness) of the developer  4  held on the developing roller  141 . Developing voltage is supplied from a power source (not illustrated) between the developing roller  141  of the developing device  14  and the photoconductor drum  11 . In addition, the developing roller  141 , the supply transport member  142 , and the agitation transport member  143  are rotated in predetermined directions by a power transmitted from the driving device (not illustrated). In addition, a two-component developer including non-magnetic toner and a magnetic carrier is used as the developer  4 . Further, the developing device  14  will be described below in detail. 
     As illustrated in  FIG. 1 , the transfer device  20  is a contact transfer device including a transfer roller that rotates while being in contact with the circumferential surface of the photoconductor drum  11  at the transfer position T, and is supplied with a transfer voltage. As the transfer voltage, a direct current voltage having a polarity opposite to the charging polarity of the toner is supplied from a power source (not illustrated). 
     As illustrated in  FIG. 2 , the drum cleaning device  15  includes a cleaning plate  15   b  that is disposed in a container-shaped main body  15   a  and cleans the photoconductor drum  11  by removing attached substances such as residual toner, and a transport member  15   c  such as a screw auger (not illustrated) that transports the attached substances collected by the cleaning plate  15   b  to an external collecting container. A plate-shaped member (e.g., a blade) made of a material such as rubber is used as the cleaning plate  15   b.    
     As illustrated in  FIG. 1 , the fixing device  40  is configured by disposing a roll type or belt type heating rotating body  41  heated by a heating unit so that a surface temperature is maintained to a predetermined temperature, and a roll type or belt type pressurizing rotating body  42  which rotates in a state of being in contact with the heating rotating body  41  with a predetermined pressure. In the fixing device  40 , a contact portion where the heating rotating body  41  and the pressurizing rotating body  42  are in contact with each other is a fixing processing portion where a necessary fixing process (heating and pressing processes) is performed. 
     The sheet feeding device  50  is disposed to be present at a position in the lower side of the image forming apparatus main body  1   a . The sheet feeding device  50  mainly includes: a single (or plural) sheet accommodating body  51  that accommodates recording sheets  5  having a desired size and type in a state in which the recording sheets  5  are stacked, and delivery devices  52   a  and  52   b  that send out the recording sheets  5  one by one from the sheet accommodating body  51 . For example, the sheet accommodating body  51  is mounted to be withdrawn to a front side of the image forming apparatus main body  1   a  (a side facing a user when the user manipulates the sheet accommodating body  51 ). 
     Between the sheet feeding device  50  and the transfer device  20 , a sheet feeding transport path  56  is provided which includes plural sheet transport roller pairs  53  and  54  and a transport guide  55  that transport a recording sheet  5  sent out from the sheet feeding device  50  to the transfer position T. The sheet transport roller pair  54  disposed immediately before the transfer position T in the sheet feeding transport path  56  is configured as, for example, a roll (registration roller) that adjusts transport timing of the recording sheet  5 . 
     At the downstream side of the transfer device  20 , a transport guide  57  is disposed to transport the recording sheet  5 , to which the toner image is transferred by the transfer device  20 , to the fixing device  40 . In addition, in the inlet of the fixing device  40 , an inlet guide member  43  is provided to guide the recording sheet  5  to the fixing processing portion where the heating rotating body  41  and the pressurizing rotating body  42  are in contact with each other, and in the outlet of the fixing device  40 , outlet guide members  44  and  45  are provided to guide the recording sheet  5  which has been subjected to the fixing processing. 
     At the downstream side of the fixing device  40 , a sheet discharge transport path  59  is provided that includes sheet discharge rollers  58  that discharges the recording sheet  5  having a toner image fixed thereon by the fixing device  40  to a sheet discharge unit  57  disposed at an upper side of the image forming apparatus main body  1   a.    
     In  FIG. 1 , reference numeral  100  indicates a control device that collectively controls the operations of the image forming apparatus  1 . The control device  100  is provided with a non-illustrated central processing unit (CPU), read only memory (ROM), or random access memory (RAM), or a bus, a communication interface, and the like that connect the CPU, the ROM, and the like. 
     &lt;Basic Operation of Image Forming Apparatus&gt; 
     Hereinafter, a basic image forming operation by the image forming apparatus  1  will be described. 
     An image forming operation at the time of forming a monochrome image, which is formed from the toner image of black K, by using the image forming device  10 , will be described. 
     When the image forming apparatus  1  receives command information requesting an image forming operation (print), the image forming device  10 , the transfer device  20 , and the fixing device  40  are started. 
     In the image forming device  10 , the photoconductor drum  11  rotates in the direction indicated by the arrow A first, and the charging device  12  charges the surface of the photoconductor drum  11  with a predetermined polarity (in the first exemplary embodiment, negative polarity) and electric potential. Subsequently, the exposure device  13  irradiates the surface of the photoconductor drum  11  with light LB emitted based on a signal of an image input to the image forming apparatus  1 , after the surface of the photoconductor drum  11  is charged, to form an electrostatic latent image configured by a predetermined potential difference on the surface. 
     Subsequently, the developing device  14  performs the development for the electrostatic latent image formed on the photoconductor drum  11  by supplying the toner charged with a predetermined polarity (negative polarity) to the electrostatic latent image so that the toner is electrostatically attached to the electrostatic latent image. With this development, the electrostatic latent image formed on the photoconductor drum  11  is visualized as the toner image developed by the toner. 
     Subsequently, when the toner image formed on the photoconductor drum  11  of the image forming device  10  is transported to the transfer position T, the transfer device  20  transfers the toner image to the recording sheet  5 . 
     In addition, in the image forming device  10  in which the transfer is terminated, the drum cleaning device  15  cleans the surface of the photoconductor drum  11  by scraping and removing attached substances such as the toner remaining on the surface of the photoconductor drum  11 . Therefore, the image forming devices  10  is in a state in which the next image forming operation is capable of being performed. 
     Meanwhile, the sheet feeding device  50  sends out the predetermined recording sheet  5  to the sheet feeding transport path  56  in accordance with the image forming operation. In the sheet feeding transport path  56 , the sheet transport roller pair  54  serving as registration rollers sends out the recording sheet  5  to be supplied to the transfer position T in accordance with the transfer timing. 
     Subsequently, the recording sheet  5  having the toner image transferred thereon is transported to the fixing device  40  via the transport guide  57 . In the fixing device  40 , a predetermined fixing process (heating and pressing processes) is performed to fix the unfixed toner image to the recording sheet  5  by causing the recording sheet  5  after the transfer to be introduced into and pass through the fixing processing portion between the rotating heating rotating body  41  and the pressurizing rotating body  42  through the inlet guide member  43 . Finally, after the fixing is completed, the recording sheet  5  is discharged by the sheet discharge rollers  58  to, the sheet discharge unit  57  provided, for example, at the upper side of the image forming apparatus  1  through the sheet discharge transport path  59 . 
     With the above described operation, the recording sheet  5  is output in a state in which a monochrome image is formed on one side of the recording sheet  5 . 
     &lt;Configuration of Developing Device&gt; 
       FIG. 2  is a cross-sectional configuration diagram illustrating the developing device according to the first exemplary embodiment together with other constituent members of the image forming device. 
     As illustrated in  FIG. 2 , the developing device  14  is provided with the apparatus housing  140  as an example of a developer accommodating container. Within the apparatus housing  140 , a developer accommodation chamber  150  is formed to accommodate the two-component developer  4 . An opening  151  is formed in a region of the apparatus housing  140  which faces the photoconductor drum  11 . In addition, within the apparatus housing  140 , the developing roller  141  as an example of a developer carrier is rotatably disposed in an arrow direction C to be partially exposed through the opening  151 . The developing roller  141  includes a magnet roller  141   a , as an example of a magnetic field generating member, which is fixedly disposed therein and includes magnetic poles each having a predetermined polarity and disposed at predetermined positions in a circumferential direction thereof, and a cylindrical developing sleeve  141   b , as an example of a developer transport member, which is disposed on the outer circumference of the magnet roller  141   a  to be rotatable at a predetermined rotational speed along the arrow direction C. The developing sleeve  141   b  is made of a non-magnetic material such as aluminum or non-magnetic stainless steel in a cylindrical shape. 
     In this exemplary embodiment, a rotation direction of the developing sleeve  141   b  is set to a direction reverse to a rotation direction of the photoconductor drum  11 . That is, as illustrated in  FIG. 2 , while the rotation direction of the photoconductor drum  11  is set to the counterclockwise direction, the rotation direction of the developing sleeve  141   b  is set to a clockwise direction. As a result, the outer circumferential surface of the developing sleeve  141   b  is moved in the same direction as the direction in which the surface of the photoconductor drum  11  is moved, in the developing region facing the photoconductor drum  11 . In addition, the rotation direction of the developing sleeve  141   b  may be set to the same direction as the rotation direction of the photoconductor drum  11 . 
     The magnet roller  141   a  includes: a developing magnetic pole S 1 , which is disposed at a position slightly displaced from a position closest to the photoconductor drum  11  to an upstream side in the rotation direction of the photoconductor drum  11  in a developing region facing the photoconductor drum  11 ; a pick-off magnetic pole N 1 , which is positioned at the downstream side in the rotation direction of the developing sleeve  141   b  to separate the developer  4  used to develop the image from the surface of the developing sleeve  141   b , and transport the separated developer  4  into the apparatus housing  140 ; a pick-up magnetic pole N 2  which is disposed at the downstream side of the pick-off magnetic pole N 1  in the rotation direction of the developing sleeve  141   b  to adsorbs the developer  4  to the surface of the developing sleeve  141   b ; a trimming magnetic pole S 2  that uniformizes the adsorbed developer  4  on the surface of the developing sleeve  141   b  by the layer thickness regulating member  144 ; and a transport magnetic pole N 3 , which is disposed at the downstream side of the trimming magnetic pole S 2  in the rotation direction of the developing sleeve  141   b  to transport the uniformized developer  4  to the developing region. In the vicinity of the upstream side of the trimming magnetic pole S 2  of the magnet roller  141   a , the layer thickness regulating member  144  is disposed to regulate the amount (layer thickness) of the developer  4  held on the surface of the developing sleeve  141   b . The layer thickness regulating member  144  is made of a columnar magnetic material, and regulates the layer thickness of the developer  4  to a predetermined value in a state in which the magnetic force of the trimming magnetic pole S 2  is applied. The developer  4  transported while being adsorbed by the magnetic poles of the magnet roller  141   a  is formed as a layer in the form of a magnetic brush shape on the surface of the developing sleeve  141   b.    
     Within the apparatus housing  140 , the supply transport member  142  is disposed obliquely downward in the vertical direction at the rear side of the developing roller  141 , in which the supply transport member  142  includes a screw auger (supply auger) or the like that draws up the developer  4  accommodated in (the bottom portion of) the developer accommodation chamber  150 , and supplies the developer  4  to the developing roller  141 . The supply transport member  142  is rotated clockwise by a driving device (not illustrated). In addition, in the apparatus housing  140 , the agitation transport member  143  is disposed obliquely upward in the vertical direction at the rear side (the opposite side to the photoconductor drum  11 ) of the supply transport member  142 , in which the agitation transport member  143  includes a screw auger (admix auger) that transports the developer  4  and supplies the developer  4  into the apparatus housing  140  while agitating the developer  4 . As a result, the agitation transport member  143  is present at a position in an approximately horizontal direction at the rear side of the developing roller  141 . While the agitation transport member  143  is also rotated by the driving device (not illustrated), the rotation direction of the agitation transport member  143  may be either of the clockwise direction and the counterclockwise direction. In the illustrated example, the rotation direction of the agitation transport member  143  is set to the clockwise direction. 
     In the exemplary embodiment, as illustrated in  FIG. 2 , the agitation transport member  143  is disposed obliquely upward in the vertical direction at the rear side of the supply transport member  142 . For this reason, in the developing device  14 , the depth of the apparatus housing  140  is set to be small and the apparatus housing  140  is miniaturized compared to a case in which the agitation transport member  143  is disposed in the horizontal direction at the rear side of the supply transport member  142 . 
     In the apparatus housing  140 , the first accommodation chamber  147  and the second accommodation chamber  148  are provided to accommodate the supply transport member  142  and the agitation transport member  143 , in which the first accommodation chamber  147  and the second accommodation chamber  148  are formed in a substantially semi-cylindrical or substantially cylindrical shape in cross section. The first accommodation chamber  147  and the second accommodation chamber  148  are partitioned by the partition wall  152  provided in the apparatus housing  140 . Further, in the illustrated example, for convenience, the apparatus housing  140  is illustrated as being integrally formed. Of course, however, the apparatus housing  140  may be configured by being divided into an upper housing (not illustrated) and a lower housing (not illustrated). 
     In addition, as illustrated in  FIG. 3 , at opposite end portions of the partition wall  152  in the longitudinal direction, first and second passageway portions  153  and  154  are formed respectively to deliver the developer  4  between the supply transport member  142  and the agitation transport member  143 . In addition, in the apparatus housing  140 , a supply port  155  is opened at the upstream side end portion of the agitation transport member  143  in the transport direction, in which the supply port supplies the developer  4  including at least the toner from a toner cartridge (not illustrated). Further, the supply port  155  may also be provided at a portion where the agitation transport member  143 , together with the apparatus housing  140 , extends to one side (right side in  FIG. 3 ) in the axial direction of the agitation transport member  143 . 
     The developer  4 , which is supplied into the apparatus housing  140  from the supply port  155 , is agitated with the developer  4  accommodated in the apparatus housing  140  while the developer  4  is transported by the agitation transport member  143 . When the developer  4 , which is transported while being agitated by the agitation transport member  143 , is transported to the end portion of the downstream side in the transport direction of the agitation transport member  143 , the developer  4  is delivered to the supply transport member  142  through the first passageway portion  153  opened in the partition wall  152 . In addition, at the downstream side end portion of the agitation transport member  143  in the transport direction, a short reverse transport blade  143   a  is provided to deliver the developer  4  from the first passageway portion  153  to the supply transport member  142  while pushing the developer  4  transported by the agitation transport member  143  back to the upstream side. 
     The developer  4 , which is delivered to the supply transport member  142 , is supplied to the developing roller  141  positioned obliquely upward while the developer  4  is transported by the supply transport member  142 . In addition, the developer  4 , which is transported to the downstream side end portion of the supply transport member  142  in the transport direction, is delivered to the supply transport member  142  positioned obliquely upward through the second passageway portion  154  opened in the partition wall  152 . In addition, at the downstream side end portion of the supply transport member  142  in the transport direction a short reverse transport blade  142   a  is provided to deliver the developer  4  from the second passageway portion  154  to the agitation transport member  143  while pushing the developer  4  transported by the supply transport member  142  back to the upstream side. 
     By the way, as illustrated in  FIG. 2 , in the developing device  14  according to the exemplary embodiment, the agitation transport member  143  is disposed obliquely upward in the vertical direction at the rear side of the supply transport member  142 . For this reason, it is required to deliver the developer  4 , which is transported to the downstream side in the transport direction by the supply transport member  142 , to the agitation transport member  143  positioned obliquely upward in the vertical direction against the gravity through the second passageway portion  154 . 
     As a result, as illustrated in  FIG. 4 , the developer  4 , which is transported to the agitation transport member  143  positioned obliquely upward in the vertical direction by the supply transport member  142 , easily stays in the region of the second passageway portion  154  due to an influence of gravitational force. Although a part  4   a  of the developer  4  is transported from the second passageway portion  154  to the agitation transport member  143 , a large amount of staying developer  4   b  flows from the supply transport member  142  into the developing roller  141 . Then, a developer holding amount per unit area of the surface of the developing roller  141  (hereinafter, referred to as “MOS”) (g/m 2 ) is increased at the end portion of the developing roller  141  which is positioned at the second passageway portion  154  side. 
     Therefore, there is a concern that in the developing device  14 , the MOS may increase at the downstream side in the transport direction of the supply transport member  142 , the MOS may not be uniform in the axial direction of the developing roller  141 , and density irregularity may be caused in the axial direction of the developing roller  141 . 
     Therefore, in the developing device  14  according to the exemplary embodiment, as illustrated in  FIG. 2 , a regulating member  160  that regulates the movement of the developer  4  from the supply transport member  142  to the developing roller  141  is provided at a position corresponding to the second passageway portion  154  that transports the developer  4  from the supply transport member  142  to the agitation transport member  143 . The regulating member  160  is provided integrally with the apparatus housing  140 , or configured as a component separate from the apparatus housing  140 , and mounted at a predetermined position of the apparatus housing  140 . Further, in the illustrated exemplary embodiment, the regulating member  160  is provided integrally with the apparatus housing  140 . 
     As illustrated in  FIG. 3 , the regulating member  160  is provided to have a predetermined length L 3  from the upstream side to the downstream side in the transport direction of the supply transport member  142  in the second passageway portion  154 , at the position corresponding to the second passageway portion  154 . The regulating member  160  includes a protrusion formed by making the inner wall surface of the partition wall  152 , which partitions the supply transport member  142  and the agitation transport member  143  in the apparatus housing  140 , protrude toward the supply transport member  142  side and the developing roller  141  side. As illustrated in  FIG. 4 , the movement of the developer  4  from the supply transport member  142  to the developing roller  141  is regulated by burying a space S (dead space) formed between the supply transport member  142  and the developing roller  141 . 
     The regulating member  160  is configured so that a side surface  160   a  positioned at the supply transport member  142  side is positioned on an extension line L 1  in the radial direction of the pick-up magnetic pole N 2  of the magnet roller  141   a . In addition, in the regulating member  160 , a side surface  160   b  positioned at the developing roller  141  side is positioned in parallel with a tangential line L 2  at an intermediate position between the pick-up magnetic pole N 2  and the trimming magnetic pole S 2  of the developing roller  141 . 
     As illustrated in  FIG. 2 , the region in which the regulating member  160  is provided corresponds to the outside of the pick-up magnetic pole N 2  of the magnet roller  141   a  in the radial direction. In a case in which the space S formed between the supply transport member  142  and the developing roller  141  by the regulating member  160  is set to be excessively narrow, there is a concern that the amount of the developer  4  supplied from the supply transport member  142  to the developing roller  141  is reduced, and on the contrary, the MOS (g/m 2 ) in the region of the developing roller  141 , which corresponds to the second passageway portion  154 , is decreased. Therefore, the arrangement and the protruding amount of the regulating member  160  including the length thereof and the like may be preferably set such that the MOS (g/m 2 ) becomes substantially uniform in the axial direction of the developing roller  141 . 
     In the developing device  14 , an opening width (gap) W of the second passageway portion  154  may be set to be larger than that of the first passageway portion  153 , as necessary. 
     In  FIG. 2 , reference numeral  156  indicates a seal member made of a synthetic resin film to seal a portion between the apparatus housing  140  and the outer circumferential surface of the photoconductor drum  11 . 
     &lt;Operation of Characteristic Part of Developing Device&gt; 
     As illustrated in  FIG. 2 , in the developing device  14  according to the first exemplary embodiment, the developing roller  141 , the supply transport member  142 , and the agitation transport member  143  are rotated at a predetermined rotational speed by the driving device (not illustrated) when the electrostatic latent image formed on the surface of the photoconductor drum  11  is developed. As illustrated in  FIG. 5 , the developer  4  accommodated in the apparatus housing  140  is transported to the downstream side in the axial direction of the agitation transport member  143  while being agitated by the agitation transport member  143 . 
     Thereafter, the developer  4  is delivered from the agitation transport member  143  to the supply transport member  142  through the first passageway portion  153 . The developer  4 , which is delivered to the supply transport member  142 , is supplied to the developing roller  141  while being transported by the agitation transport member  143 , and provided for the development. The developer  4 , which is transported to the downstream side end portion of the supply transport member  142  in the axial direction, is delivered from the supply transport member  142  to the agitation transport member  143  through the second passageway portion  154 . 
     In that event, as illustrated in  FIG. 5 , the regulating member  160  is provided in a region corresponding to the second passageway portion  154  to regulate the movement of the developer  4  from the supply transport member  142  to the developing roller  141  side. For this reason, as illustrated in  FIG. 6 , while a part of the developer  4 , which is delivered from the supply transport member  142  to the agitation transport member  143  through the second passageway portion  154 , moves to the developing roller  141 , the majority of the developer  4  moves to the agitation transport member  143  through the second passageway portion  154 . Therefore, it is inhibited that the developer  4  is excessively supplied in the region of the developing roller  141  which corresponds to the second passageway portion  154  and that density irregularity is occurred along the axial direction of the developing roller  141 . 
     As illustrated in  FIG. 2 , because the side surface  160   a  of the regulating member  160 , which is positioned at the supply transport member  142  side, is positioned on the extension line L 1  in the radial direction of the pick-up magnetic pole N 2  of the magnet roller  141   a , the absorption of the developer  4  to the developing roller  141  is effectively inhibited by the pick-up magnetic pole N 2 . In addition, because the side surface  160   b  of the regulating member  160  located at the side of the developing roller  141  is positioned in parallel with the tangential line L 2  positioned at an intermediate position between the pick-up magnetic pole N 2  and the trimming magnetic pole S 2  of the developing roller  141 , the developer  4  moving from the supply transport member  142  to the developing roller  141  is effectively regulated along the magnetic brush of the developer  4  which is formed by the pick-up magnetic pole N 2  and the trimming magnetic pole S 2 . 
     The exemplary embodiment has been described as being applied to the monochrome image forming apparatus, but the exemplary embodiment may, of course, be equally applied to a color image forming apparatus having plural image forming devices. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.