Patent Publication Number: US-8126373-B2

Title: Toner supply device and image forming apparatus that prevents toner from being scattered from the device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present patent application claims priority pursuant to 35 U.S.C. §119 from Japanese Patent Application Nos. 2007-254875, filed on Sep. 28, 2007, and 2007-254882, filed on Sep. 28, 2007 in the Japan Patent Office, the entire contents of each of which are hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a toner supply device useable in an image forming apparatus such as a copier, a facsimile machine, and a printer, and an image forming apparatus including the toner supply device. 
     2. Description of the Background 
     Image forming apparatuses are used as copiers, printers, facsimile machines, and multi-functional devices combining several of the foregoing capabilities. A conventional image forming apparatus includes a detachably mountable toner supply device to supply toner to a developing device. When the toner supply device is mounted in or detached from the image forming apparatus with an opening provided in the toner supply device to discharge toner uncovered, a portion of the toner may be scattered from the opening, resulting in failures such as contamination of the image forming apparatus and/or its surrounding area. To prevent such scattering of toner, a shutter for alternately uncovering and covering the opening may be provided in the image forming apparatus. In such configuration, for example, the opening is uncovered by the shutter when the toner supply device is mounted in the image forming apparatus but covered with the shutter when the toner supply device is detached from the image forming apparatus. 
     A conventional toner supply device includes a shutter on a bottom wall of the toner supply device to discharge toner, movable between a closed position to close the toner discharge port and an open position to open the toner discharge port. The shutter is moved along an outer face of the bottom wall of the toner supply device by a guide member provided on the outer face of the bottom wall behind the toner discharge port with respect to the shutter. A seal member contactable against the outer face of the bottom wall is attached to the shutter so as to seal the toner discharge port when the shutter is at the closed position to close the toner discharge port. Such contact between the seal member and the outer face of the bottom wall can prevent a gap from forming between the shutter and the outer face of the bottom wall of the toner supply device, thereby providing excellent sealability. 
       FIG. 19  is a schematic view illustrating a toner transfer portion from a toner supply device  100  to a developing device  200  in an image forming apparatus. In  FIG. 19 , an opening  109  into which a shutter  125  is inserted is formed on a side wall of a case  101  that forms a part of a toner flow path t 1 . The shutter  125  is inserted as illustrated in  FIG. 20  to open and close the toner flow path t 1 . 
     In this regard, the shutter  125  needs to reliably close the toner flow path t 2  and fit snugly in the opening  109 . 
       FIGS. 21 and 22  illustrate sectional views cut along a line XXI-XXI of  FIG. 20 . As illustrated in  FIG. 21 , if there are gaps  401  and  402  between the shutter  125  and the opening  109 , toner may be inadvertently scattered from such gaps  401  and  402 . Such toner scattering may occur, in particular, during operation of the image forming apparatus. For example, as illustrated in  FIG. 20 , during operation of the image forming apparatus, toner whose fluidity is increased by an agitator flows down from an upper portion of the toner flow path t 1 . As a result, a portion of the toner may be scattered through the gaps  401  and  402  to the outside of the case  101 . Further, at a lower portion of the toner flow path t 1  close to the developing device  200 , a screw  204  for transporting the toner in a direction indicated by an arrow t 2  in  FIG. 20  flips the toner upward in directions indicated by arrows t 3 . As a result, a portion of the toner may be scattered from the gaps  401  and  402 . When a toner having a relatively small particle diameter is used, such toner may more readily pass through the gaps to the outside, thereby resulting in more notable toner scattering. Alternatively, using a relatively high-speed developing device may cause the screw to flip up the toner intensively, similarly resulting in more notable toner scattering. 
     To prevent toner from being scattered from the opening  109 , such gaps need be filled by closely contacting the shutter  125  against side surfaces  403  and  404  as illustrated in  FIG. 22 . 
     However, the shutter  125  and the side surfaces  403  and  404  may have dimensional tolerances, resulting in a discrepancy in size, and thus a discrepancy in fit, between the shutter  125  and the opening  109 . In such a case, if the shutter  125  is too large compared to the opening  109 , the shutter  125  may be prevented from moving into the opening  109 , or moved only with great difficulty, thereby degrading the slidability of the opening  109 . By contrast, if the shutter  125  is too small compared to the opening  109 , gaps may appear between the shutter  125  and the side surfaces  403  and  404 , resulting in toner leakage from the gaps. 
     Hence, in the above-described conventional toner supply device, the toner discharge port is provided to the outer face of the bottom wall of the toner supply device and the seal member is attached to the shutter so as to contact the outer face of the bottom wall of the toner supply device to prevent gaps from appearing between the shutter and the outer face of the bottom wall of the toner supply device. 
     However, in the conventional toner supply device, sufficient consideration is not given to gaps appearing between a guide member and end portions in the width direction of the shutter, which may result in toner leakage from the gaps. 
     In view of the above-described situation, the present disclosure provides a toner supply device capable of reliably opening and closing a shutter member to prevent toner from being scattered from the device, and an image forming apparatus including the toner supply device. 
     SUMMARY OF THE INVENTION 
     At least one exemplary embodiment of the present invention provides a toner supply device capable of reliably opening and closing a shutter member to prevent toner from being scattered from the device, and an image forming apparatus including the toner supply device. 
     In one exemplary embodiment of the present invention, a toner supply device includes a toner container, a transport-path forming member, an opening, a shutter member, and a first seal member. The toner container stores toner. The transport-path forming member forms a transport path to transport the toner stored in the toner container to the outside of the toner container. The opening is provided at a side wall of the transport-path forming member. The shutter member is movable between a closed position to close the transport path by being inserted in the opening and an open position to open the transport path. The first seal member fills a gap between an inner wall of the opening and the shutter member in a toner transport direction in which the toner is transported through the transport path. When the shutter member is inserted in the opening, the shutter member is elastically deformable in a deformation direction perpendicular to both the toner transport direction and a moving direction of the shutter member, and when the shutter member is not inserted in the opening, the shutter member is wider than the opening in the deformation direction. 
     In another exemplary embodiment of the present invention, an image forming apparatus includes a latent image carrier, a developing unit, and a toner supply device. The latent image carrier carries a latent image. The developing unit develops the latent image carried on the latent image carrier with toner into a toner image. The toner supply device supplies the toner to the developing unit. The toner supply device includes a toner container, a transport-path forming member, an opening, a shutter member, and a first seal member. The toner container stores the toner. The transport-path forming member forms a transport path to transport the toner stored in the toner container to the developing unit. The opening is provided at a side wall of the transport-path forming member. The shutter member is movable between a first position to close the transport path by being inserted in the opening and a second position to open the transport path. The first seal member fills a gap between an inner wall of the opening and the shutter member in a toner transport direction in which the toner is transported through the transport path. When the shutter member is inserted in the opening, the shutter member is elastically deformable in a deformation direction perpendicular to both the toner transport direction and a moving direction of the shutter member, and when the shutter member is not inserted in the opening, the shutter member is wider than the opening in the deformation direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily acquired as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a schematic view illustrating a configuration of an image forming apparatus according to an exemplary embodiment of the present invention; 
         FIG. 2  is a schematic view illustrating a configuration of a toner supply device according to an exemplary embodiment of the present invention; 
         FIG. 3  is a schematic view illustrating a state in which the toner supply device of  FIG. 2  is detached from the image forming apparatus; 
         FIG. 4  is a schematic view illustrating a shape of a shutter according to an exemplary embodiment; 
         FIG. 5  is a schematic view illustrating a state before the shutter of  FIG. 4  is inserted into an opening; 
         FIG. 6  is a schematic view illustrating a state after the shutter of  FIG. 4  is inserted into the opening; 
         FIG. 7  is a schematic view illustrating the shutter of  FIG. 4 , fitted with a seal member; 
         FIG. 8  is a schematic view illustrating the shutter of  FIG. 7 , to which a seal is attached; 
         FIG. 9  is a schematic view illustrating another shape of the seal; 
         FIG. 10  is a sectional view illustrating the shutter and the opening cut along a line X-X in  FIG. 2 ; 
         FIG. 11  is a schematic view illustrating a state in which the seal is deformed when a cutout portion is not formed in a film member of the seal; 
         FIG. 12  is a top view illustrating an open state in which a toner supply port is opened with the shutter; 
         FIG. 13  is a top view illustrating a closed state in which the toner supply port is closed with the shutter; 
         FIG. 14  is a side view illustrating the open state in which the toner supply port is opened with the shutter; 
         FIG. 15  is a side view illustrating the closed state in which the toner supply port is closed with the shutter; 
         FIG. 16  is a schematic view illustrating a configuration of a shutter with grooves according to an exemplary embodiment; 
         FIG. 17  is an enlarged view illustrating a shutter without grooves and an inner wall of the opening; 
         FIG. 18  is an enlarged view illustrating a shutter with grooves and the inner wall of the opening; 
         FIG. 19  is a schematic view illustrating an opening into which a shutter is inserted in a conventional toner supply device; 
         FIG. 20  is a schematic view illustrating operations of the shutter in the conventional toner supply device of  FIG. 20 ; 
         FIG. 21  is a schematic view illustrating a state in which there are gaps between an opening and a shutter; and 
         FIG. 22  is a schematic view illustrating a state in which there is no gap between the opening and the shutter. 
     
    
    
     The accompanying drawings are intended to depict exemplary embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In describing exemplary embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results. 
     Below, taking as an example a tandem-type color laser copier (hereinafter a “copier”) in which a plurality of photoconductors are arranged side by side, an image forming apparatus  1000  according to an exemplary embodiment of the present invention is described. 
       FIG. 1  is a schematic view illustrating a configuration of the image forming apparatus  1000  according to this exemplary embodiment. As illustrated in  FIG. 1 , the image forming apparatus  1000  includes, for example, a printer section  10 , a sheet feed section  11  on which the printer section  10  is mounted, and a scanner  12  disposed on the printer section  10 . The image forming apparatus  1000  also includes an automatic document feeder  400  disposed on the scanner  12 . 
     The printer section  10  has an image forming unit  20  including, for example, four process cartridges  18 Y,  18 M,  18 C, and  18 K to form images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Hereinafter, the letters Y, M, C, and K added to numeral codes indicate components or members for yellow, magenta, cyan, and black, respectively. In addition to the process cartridges  18 Y,  18 M,  18 C, and  18 K, the image forming apparatus  1000  further includes an optical write unit  21 , an intermediate transfer unit  17 , a secondary transfer device  22 , a pair of registration rollers  49 , and a fixing device  25  using, for example, a belt fixing system. 
     The optical write unit  21  includes, for example, a light source, a polygon mirror, an f-θ lens, and a reflection mirror, and emits a laser beam onto the surface of each photoconductor based on scanned image data. 
     Each of the process cartridges  18 Y,  18 M,  18 C, and  18 K includes a drum-shaped photoconductor  1 , a charger, a developing device  200 , a drum cleaner, and a discharger. 
     Below, taking the yellow process cartridge  18 Y as an example, the process cartridges  18 Y,  18 M,  18 C, and  18 K are described further in detail. 
     The charger serving as a charging unit uniformly charges the surface of the photoconductor  1 Y. The charged surface of the photoconductor  1 Y is irradiated with a laser beam modulated and deflected by the optical write unit  21  according to the scanned image data. As a result, the electric potential of a portion irradiated or exposed with the laser beam decreases, so that an electrostatic latent image for yellow is formed on the surface of the photoconductor  1 Y. The electrostatic latent image for yellow is developed with the developing device  200 Y into a yellow toner image. 
     The yellow toner image formed on the photoconductor  1 Y is primarily transferred onto an intermediate transfer belt  4 . After the primary transfer process, the drum cleaner removes residual toner remaining on the surface of the photoconductor  1 Y. 
     After the cleaning with the drum cleaner, the charge remover removes the charge from the photoconductor  1 Y. Then, the charger uniformly charges the surface of the photoconductor  1 Y again, and thus the photoconductor  1 Y is initialized. Likewise, a series of processes similar to those described above is performed at each of the other process cartridges  18 M,  18 C, and  18 K. 
     Next, the intermediate transfer unit  17  is described. 
     The intermediate transfer unit  17  includes the intermediate transfer belt  4 , a belt cleaner  90 , a tension roller  14 , a driving roller  15 , a secondary transfer back-up roller  16 , and primary transfer bias rollers  62 Y,  62 M,  62 C, and  62 K, for example. 
     The intermediate transfer belt  4  is stretched between a plurality of rollers including the tension roller  14 . As the driving roller  15  is rotated by a belt driving motor, the intermediate transfer belt  4  is endlessly moved in a clockwise direction in  FIG. 1 . 
     The four primary-transfer bias rollers  62 Y,  62 M,  62 C, and  62 K are disposed so as to contact an inner circumferential surface of the intermediate transfer belt  4  and receive primary-transfer biases applied from a power supply. The primary-transfer bias rollers  62 Y,  62 M,  62 C, and  62 K press the intermediate transfer belt  4  from the inner circumferential surface toward the photoconductors  1 Y,  1 M,  1 C, and  1 K, respectively, to form primary-transfer nips. At each primary-transfer nip, the primary-transfer bias forms primary-transfer electric fields between each photoconductor and the corresponding primary-transfer bias roller. 
     The above-described yellow toner image formed on the photoconductor  1 Y is primarily transferred onto the intermediate transfer belt  4  by the primary-transfer electric field and nip pressure at the primary transfer nip. Magenta, cyan, and black toner images on the photoconductors  1 M,  1 C, and  1 K are primarily transferred onto the yellow toner image so as to be sequentially superimposed one on another. Thus, a four-color composite toner image (hereinafter a “four-color toner image”), including multiple toner images, is formed on the intermediate transfer belt  4 . 
     The four-color toner image superimposingly transferred on the intermediate transfer belt  4  is secondarily transferred onto a transfer sheet, serving as a recording material, at a secondary transfer nip. After passing through the secondary transfer nip, the belt cleaner  90  sandwiching the intermediate transfer belt  4  between it and the driving roller  15  removes residual toner remaining on the surface of the intermediate transfer belt  4 . 
     Next, the secondary transfer device  22  is described. 
     In  FIG. 1 , the secondary transfer device  22  is disposed below the intermediate transfer unit  17 . In the secondary transfer device  22 , a sheet conveyance belt  24  is extended between two tension rollers  23   a  and  23   b . As at least one roller of the tension rollers  23   a  and  23   b  is driven, the sheet conveyance belt  24  is endlessly moved in a counterclockwise direction in  FIG. 1 . The tension roller  23   a  sandwiches the intermediate transfer belt  4  and the sheet conveyance belt  24  between it and the secondary-transfer back-up roller  16  of the intermediate transfer unit  17 . Such sandwiching forms the secondary transfer nip at which the intermediate transfer belt  4  of the intermediate transfer unit  17  contacts the sheet conveyance belt  24  of the secondary transfer device  22 . A secondary transfer bias having a polarity opposite to the polarity of the toner is supplied to the tension roller  23   a  from a power supply. Such supply of the secondary transfer bias forms secondary-transfer electric fields to electrostatically move the four-color toner image on the intermediate transfer belt  4  toward the tension roller  23   a . The pair of registration rollers  49  feeds the transfer sheet so as to synchronize with the four-color toner image on the intermediate transfer belt  4 . The four-color toner image is secondarily transferred onto the transfer sheet by the secondary-transfer electrical field and nip pressure at the secondary transfer nip. 
     Alternatively, instead of the above-described secondary transfer system to supply the secondary transfer bias to the tension roller  23   a , a charger may be provided to charge the transfer sheet in a non-contact manner, for example. 
     The sheet feed device  11  disposed at a lower portion of the image forming apparatus  1000  includes a plurality of vertically stacked sheet feed cassettes  44 . Each sheet feed cassette  44  is capable of storing a plurality of transfer sheets stacked in a bundled state and pressing a sheet feed roller  42  against a topmost sheet of the bundled transfer sheets. As the sheet feed roller  42  is rotated, the topmost transfer sheet is fed toward a sheet feed path  46 . 
     The sheet feed path  46  into which the transfer sheet is fed from the sheet feed cassette  44  includes a plurality of pairs of conveyance rollers  47  and a pair of registration rollers  49  that is provided near an end portion of the sheet feed path  46 . The transfer sheet conveyed to the pair of registration rollers  49  is sandwiched between the pair of registration rollers  49 . Meanwhile, in the intermediate transfer unit  17 , the four-color toner image formed on the intermediate transfer belt  4  is conveyed into the secondary transfer nip as the intermediate transfer belt  4  is endlessly moved. The pair of registration rollers  49  feeds the transfer sheet sandwiched therebetween at such a timing that the transfer sheet closely contacts the four-color toner image at the secondary transfer nip. By closely contacting the four-color toner image with the transfer sheet at the secondary transfer nip, the four-color toner image is secondarily transferred onto the transfer sheet to form a full-color image on the transfer sheet of white color, for example. As the sheet conveyance belt  24  is endlessly moved, the transfer sheet having the full-color image passes through the secondary transfer nip and is fed from the sheet conveyance belt  24  to the fixing device  25 . 
     The fixing device  25  includes a belt unit and a pressure roller  27 . The belt unit includes a fixing belt  26  and two, first and second, rollers. The fixing belt  26  is extended between the first and second rollers so as to be endlessly movable. The pressure roller  27  is pressed against the first roller. The fixing belt  26  and the pressure roller  27  contact each other to form a fixing nip at which the transfer sheet received from the sheet conveyance belt  24  is sandwiched. The first roller pressed by the pressure roller  27  includes a heat source for generating heat while pressing against the fixing belt  26 . The fixing belt  26  pressed by the first roller heats the transfer sheet sandwiched at the fixing nip. Such heat and pressure at the fixing nip fixes the full-color image on the transfer sheet. 
     After the fixing process in the fixing device  25 , the transfer sheet is stacked on a stack portion  57  provided to a left-side plate of an apparatus housing in  FIG. 1 , or is returned to the secondary transfer nip to form a toner image on another face of the transfer sheet. 
     When copying a bundle of documents, the bundle of documents may be set on a document table  30  of the automatic document feeder  400 . Alternatively, if one side of the documents is bound in a book form, the documents are set on a contact glass  32 . Before setting the documents, the automatic document feeder  400  is opened relative to a body of the image forming apparatus to expose the contact glass  32  of the scanner  12  to the outside. After placing the one-side bound documents on the contact glass  32 , the automatic document feeder  400  is closed to press the documents against the contact glass  32 . 
     After setting the documents, a copy start button is pressed to start a document reading operation of the scanner  12 . Alternatively, if the bundle of documents is set on the automatic document feeder  400 , the automatic document feeder  400  automatically feeds the sheet documents one by one to the contact glass  32  before the document reading operation. 
     In the document reading operation, a first carriage  33  and a second carriage  34  start running, and a light source of the first carriage  33  emits light. The light is reflected on the surface of the document and a mirror of the second carriage  34 , passes through a focus lens  35 , and enters into a reading sensor  36 . The reading sensor  36  creates image data based on the entered light. 
     In parallel with the document reading operation, components in the process cartridges  18 Y,  18 M,  18 C, and  18 K, the intermediate transfer unit  17 , the secondary transfer device  22 , and the fixing device  25  start driving. The driving of the optical write unit  21  is controlled based on the image data created by the reading sensor  36  so as to form yellow, magenta, cyan, and black toner images on the photoconductors  40 Y,  40 M,  40 C, and  40 K, respectively. The toner images are superimposed on the intermediate transfer belt  4  so that a full-color toner image is formed on the intermediate transfer belt  4 . 
     At substantially the same time as the start of the document reading operation, the sheet feed device  11  starts a sheet feed operation. In the sheet feed operation, as one of the sheet feed rollers is selected to rotate, a transfer sheet is fed from a corresponding one of the sheet feed cassettes  44  stacked in a paper bank  43 . The transfer sheet fed from the corresponding sheet feed cassette  44  is separated one by one with a corresponding separation roller  45 , moved into the sheet-feed path  46 , and conveyed toward the secondary transfer nip with the pair(s) of conveyance rollers  47 . 
     Instead of feeding from the sheet feed cassette  44 , transfer sheets may be fed from a manual feed tray  51 . In such case, as a manual feed roller  50  is selected and rotated to feed the transfer sheets from the manual feed tray  51 , a separation roller  52  separates and feeds the transfer sheets one by one to a manual feed path  53  of the printer section  10 . 
     When forming a multiple-color image of more than two color toners, the image forming apparatus  1000  holds the upper extending face of the intermediate transfer belt  4  substantially horizontal so that the upper extending surface contacts the photoconductors  1 Y,  1 M,  1 C, and  1 K. Alternatively, when forming a black-and-white image of only black toner, a tilting mechanism tilts the intermediate transfer belt  4  down to the left in  FIG. 1  so as to separate the upper extending face from the photoconductors  1 Y,  1 M,  1 C. Only the photoconductor  1 K among the four photoconductors is rotated in the counterclockwise direction in  FIG. 1  to form a black toner image. At this time, the developing devices  200 Y,  200 M, and  200 C as well as the photoconductors  1 Y,  1 M, and  1 C may be stopped, thereby preventing them from being unnecessarily wasted. 
     According to this exemplary embodiment, the image forming apparatus  1000  includes a control unit and an operation display unit. The control unit also includes a CPU (central processing unit) to control components in the image forming apparatus  1000 . The operation display unit includes a liquid crystal display and various key buttons. An operator performs key input operations through the operation display unit to send commands to the control unit. In such operations, the operator is allowed to select one of, for example, three modes as a simplex print mode for forming an image on only one side of a transfer sheet. The three simplex print modes are, for example, direct ejection mode, reverse ejection mode, and reverse decurling ejection mode. 
       FIG. 2  is a schematic view illustrating a toner supply device  100  to supply toner to a developing device  200 . The toner supply device  100  is the distinctive feature of the image forming apparatus according to this exemplary embodiment. 
     The toner supply device  100  is mounted in the image forming apparatus to supply toner to the developing device  200 . The toner supply device  100  includes a case  101 , agitators  102 ,  103 , and  104 , and a shutter  105 , for example. The toner supply device  100  is detachably mountable in the image forming apparatus. When the toner supply device  100  is mounted in the image forming apparatus, a supply port  108  is communicated with a toner receive port  203  of the developing device  200  to supply toner. 
     In  FIG. 3 , the shutter  105  is biased by a coil spring in a direction f 1  to close the shutter  105 . When the toner supply device  100  is detached from the image forming apparatus, the supply port  108  is closed with the shutter  105 . When the toner supply device  100  is installed to the image forming apparatus, the toner supply device  100  approaches the developing device  200  in a direction indicated by an arrow ml of  FIG. 3  and mounted to the developing device  200  in a state illustrated in  FIG. 2 . At this time, a developing device case  201  pushes open the shutter  105 , thereby communicating the supply port  108  with the toner receive port  203 . 
       FIG. 4  is a perspective view illustrating a shutter  105  according to an exemplary embodiment of the present invention. The shutter  105  includes leaf spring portions  105   a . Each leaf spring portion  105   a  is deformable in a horizontal direction, thereby allowing a front-end portion of the shutter  105  to be deformed in directions indicated by arrows m 2 . According to this exemplary embodiment, since the shutter  105  is biased by the coil spring from one side, the shutter  105  needs to have stiffness so as not to be deformed vertically. Hence, the shutter  105  employs the leaf springs to obtain preferable elasticity in the horizontal direction and preferable stiffness in the vertical direction. 
     As illustrated in  FIG. 5 , according to this exemplary embodiment, the shutter  105  is provided with convex portions  105   b , making the width of the shutter  105  greater than the width of an opening  109  into which the shutter  105  is inserted. As illustrated in  FIG. 6 , deformation of the leaf spring portions  105   a  reduces the width of the shutter  105 , thereby allowing the shutter  105  to be inserted to the opening  109 . The convex portions  105   b  limit an area contacting a wall face  101   a  of the opening  109  to only a rear-end portion  105   c  of each convex portion  105   b . Such configuration can reduce friction between the wall face  101   a  and the shutter  105 , thereby allowing the shutter  105  to slide against the wall face  101   a  with reduced load. 
     The width of the shutter  105  and the size of the opening  109  are determined based on, for example, sealability, slidability, and the amount of deformation suitable for the shutter  105 . If the width of the shutter  105  is too large, the restoration force of the leaf spring portions  105   a  would increase, thereby degrading the slidability of the shutter  105 . Further, as described below with reference to  FIG. 11 , such configuration may increase the amount of deformation of a seal member, thereby resulting in toner scattering. 
     By contrast, if the width of the shutter  105  is too small, the side faces of the shutter  105  would not be able to sufficiently contact the wall face  101   a  of the opening  109 , thereby preventing a desired degree of sealability from being obtained. 
     Therefore, according to this exemplary embodiment, the maximum widths of the shutter  105  and the opening  109  are set to, for example, approximately 15.4 mm and approximately 15 mm, respectively. 
     Further, according to this exemplary embodiment, the shutter  105  is used along with two seal members. One is a seal member  107  fitted into an opening at a middle portion of the shutter  105  as illustrated in  FIG. 7 . The other is a seal  106  covering the upper face of the shutter  105  as illustrated in  FIG. 8 . It is to be noted that the shape of the seal  106  is not limited to the shape illustrated in  FIG. 8 , but may be a shape illustrated in  FIG. 9 , for example. 
     The seal  106  includes a sponge member  106   a  and a film member  106   b  that covers an upper face of the sponge member  106   a . A cutout portion  106   c  is formed in the film member  106   b.    
       FIG. 10  is a sectional view illustrating the shutter  105  and the opening  109  cut along a line X-X in  FIG. 2 . The shutter  105  contacts the wall face of the opening  109  at the rear-end portion  105   c  as illustrated in  FIG. 6  as well and serves to support the entire shutter  105  including the seal members. The seal member  107  covers the opening, which is formed to provide the shutter  105  with the leaf spring portions  105   a , and provides preferable elasticity in the vertical direction to the shutter  105 . The seal  106  also provides preferable elasticity in the vertical direction to the shutter  105  to more closely contact the upper and lower faces of the opening  109 . Further, the seal  106  is deformable by being pressed horizontally, thereby filling gaps between the shutter  105  and the opening  109 . The film member  106   b  covers the upper face of the seal  106  to maintain the slidability of the shutter  105  and protect the surface of the seal  106 . The cutout portion  106   c  of the film member  106   b  serves to absorb the deformation of the film member  106   b  in the horizontal direction. If it were not for the cutout portion  106   c , the film member  106   b  would be deformed in a waved form as illustrated in  FIG. 11 . Such waved deformation might generate gaps  106   g , thereby resulting in toner scatter. By contrast, according to this exemplary embodiment, the cutout portion  106   c  serves to absorb such deformation, thereby preventing toner from being scattered from gaps. The cutout portion  106   c  may be formed at a middle portion of the seal  106  so as to have a width of  6  mm, for example. 
     A front-end portion  106   d  of the seal  106  is wider than the opening  109  of the shutter  105 . When the shutter  105  is inserted into the opening  109 , the front-end portion  106   d  is shortened in the width direction or deformed inwardly so as to fill in gaps in the width direction as illustrated in  FIG. 12 . If the width of the front-end portion  106   d  of the seal  106  were too small, gaps might occur between the front-end portion  106   d  of the seal  106  and the wall face of the opening  109 , thereby resulting in toner scattered from the gap. By contrast, if the width of the front-end portion of the seal  106  were too large, the front-end portion  106   d  of the seal  106  might become entangled with the sliding face of the shutter  105 , thereby degrading the slidability of the shutter  105  or causing foreign material to get into the developing device  200 . Hence, according to this exemplary embodiment, while the width of the front-end portion of the shutter  105  is set to, for example, approximately 15.4 mm, the width of the front-end portion of the seal  106  is set to a slightly larger size, for example, approximately 15.7 mm, so as to ensure a good balance between sealability and slidability. 
     The width of a middle portion  106   e  following the front-end portion  106   d  is narrower than the width of the shutter  105 . Further, the width of a rear-end portion  106   f  of the seal  106  is substantially equal to or slightly narrower than the width of the shutter  105 . Changing the width of the seal  106  as described above can provide a good balance between the sealability of the seal  106  against the opening  109  and the slidability of the shutter  105 . 
     The above-described configuration can reduce the load for opening and closing the shutter  105  to, for example, a range of between approximately 0.3 kgf to approximately 0.5 kgf. 
     Next, a description is given of the shape of the front-end portion  106   d  of the seal  106 . 
       FIG. 12  is a sectional view illustrating an open state in which the toner supply port  108  is opened with the shutter  105 , which is cut along a line XII-XII in  FIG. 2 . In this state, the shutter  105  acts to open and close the opening  109 . Except for cases in which the toner supply device  100  is detached from the image forming apparatus for maintenance and so on, the shutter  105  is in the open state. When the toner supply device  100  is operative, toner with increased fluidity flows into the toner supply port  108 . Therefore, when the toner supply port  108  is opened, the shutter  105  needs to provide a relatively high sealability against the opening  109 . Hence, according to this exemplary embodiment, by setting the width of the front-end portion  106   d  of the seal  106  wider than the width of the opening  109 , the front-end portion  106   d  of the seal  106  can closely contact the inner wall of the opening  109 . Accordingly, gaps between the front-end portion  106   d  of the seal  106  and the inner wall of the opening  109  can be securely filled, thereby preventing toner leak. 
     Next, a description is given of the shape of the middle portion  106   e  of the seal  106 . The middle portion  106   e  serves to block the toner flowing down the inside walls of the case  101  when the toner supply port  108  (the toner flow path t 1 ) is closed with the shutter  105 . The shutter  105  closes the toner supply port  108  when the toner supply device  100  is detached from the image forming apparatus. In such state, since the image forming apparatus is not operating and the toner is not moving, the toner supply port  108  need not provide such high sealability. Hence, as illustrated in  FIG. 13 , the width of the middle portion  106   e  of the seal  106  is set narrower than the width of the shutter  105 . As described above, such configuration can reduce the area of a friction face between the wall face  101   a  and the shutter  105 , thereby privileging slidability over sealability. It is to be noted that although the gaps  108   a  between the wall face  101   a  and the shutter  105  appear somewhat wide in  FIG. 13 , actually the gaps are set to a relatively small width of, for example, approximately 0.2 mm. 
     Next, a description is given of the rear-end portion  106   f  of the seal  106 . 
     When the toner supply port  108  (the toner flow path t 1 ) is closed with the shutter  105  as illustrated in  FIG. 13 , the rear-end portion  106   f  serves to close the opening  109 . However, the shutter  105  takes this position when the toner supply device  100  is detached from the image forming apparatus, which is not so frequent. Further, in such state, because the toner supply device  100  is stopped, the fluidity of toner is not so high. Hence, according to this exemplary embodiment, the width of the rear-end portion  106   f  of the seal  106  is set substantially equal to or smaller than the width of the opening  109  or the shutter  105 . Such configuration can provide sufficient sealing of the opening  109  and slidability of the shutter  105  so as not to cause failures in actual use. 
     As described above, the seal  106  is configured to have different widths in consideration of sealability suitable for each of the open and closed states of the toner supply port  108  (the toner flow path t 1 ) with the shutter  105 , thereby allowing the shutter  105  to achieve excellent balance between sealability and slidability. 
       FIG. 14  is a sectional view illustrating a section XIV-XIV of  FIG. 12 . As illustrated in  FIG. 14 , the seal member  107  has a thickness capable of passing through the shutter  105  and, at the same time, protruding from the bottom face of the shutter  105  by approximately 0.6 mm, for example. The seal member  107  serves to close the opening  109  when the toner supply port  108  is opened with the shutter  105  as illustrated in  FIG. 14 . In such open state, the seal member  107  is positioned in the opening  109 , and the shutter  105  is more closely contacted against the inner wall of the opening  109  in the vertical direction because of the portion protruding in a downward direction of the seal member  107  by approximately 0.6 mm. When the shutter  105  is in such open state, the image forming apparatus is operative and toner with increased fluidity flows into the side of the developing device  200  through the toner flow path t 1 , resulting in the need for relatively high sealability of the shutter  105 . Hence, the above-described configuration allows the shutter  105  to more closely contact the inner wall of the opening  109 , thereby achieving such high sealability. 
     By contrast, when the seal member  107  is detached from the opening  109  or the toner supply port  108  (the toner flow path t 1 ) is closed with the shutter  105  as illustrated in  FIG. 15  (illustrating a section cut along a line XV-XV in  FIG. 13 ), the shutter  105  is slightly loosely inserted in the opening  109 . When the toner supply port  108  is closed with the shutter  105 , the toner supply device  100  is not operative and an intensive flow of toner is not generated. Hence, in such closed state, the slidability of the shutter  105  is prioritized over the sealability of the shutter  105  against the opening  109 . 
     By using the seal member  107  as described above, the thickness of the seal member  107  can be varied based on which should be prioritized, sealability or slidability, so that the shutter  105  is allowed to strike a good balance between sealability and slidability. 
       FIG. 16  illustrates a shutter member  115  in which vertical grooves  115   c  are formed in convex portions  115   b  corresponding to the convex portions  105   b  of the shutter  105  of  FIG. 4 . The grooves  115   c  let out fine particles, including toner particles, sandwiched between the shutter  115  and the inner wall face of the case  101 . 
       FIG. 17  is an enlarged view illustrating the wall face sliding against the shutter  105  not having such grooves. Since the shutter  105  is deformed inside the opening, the convex portions  105   b  of the shutter  105  are slightly inclined relative to the wall face. Accordingly, when the shutter  105  is closed or moved to the left side in  FIG. 17 , fine particles  300  may clog an inclined gap, resulting in operational failure of the shutter  105 . 
     By contrast, as illustrated in  FIG. 18 , the shutter  115  having the grooves  115   c  can let out fine particles into the grooves  115   c , thereby preventing the clogging of the particles. 
     As described above, according to the above-described exemplary embodiment, the toner supply device  100  includes the case  101  serving as both the toner container that stores toner and the transport path member that forms a transport path for transporting the toner stored in the case  101 , the toner flow path t 1  serving as the transport path, the opening  109  serving as the opening formed in one side face of the case  101 , the shutter  105  serving as the shutter member movable between the closed position to close the toner flow path t 1  by being inserted to the opening  109  and the open position to open the toner flow path t 1 , and the seal  106  serving as the seal member to fill gaps appearing in the toner transport direction of the toner flow path t 1  between the inner wall of the opening  109  and the shutter  105 . In the toner supply device  100 , the shutter  105  is elastically deformable in a deformation direction perpendicular to both the toner transport direction and the movable direction of the shutter  105  when the shutter  105  is inserted in the opening  109 . A width of the shutter  105  is larger than a width of the opening  109  in the deformation direction when the shutter  105  is not inserted in the opening  109 . Such configuration allows the shutter  105  to be inserted in the opening  109  while being elastically deformed in the deformation direction. Thus, when the shutter  105  is inserted in the opening  109 , the width of the shutter  105  can be equal to the width of the opening  109  in the deformation direction. In this regard, if the width of the shutter  105  in the deformation direction with the shutter  105  being inserted in the opening  109  were too large compared to the width of opening  109 , the slidability of the shutter  105  might be degraded. By contrast, if the width of the shutter  105  in the deformation direction with the shutter  105  being inserted in the opening  109  were too small compared to the width of opening  109 , gaps might appear between the shutter  105  and the inner wall of the opening  109 . Hence, according to the above-described configuration, the toner supply device  100  can prevent such degradation of the slidability and appearance of gaps. 
     Further, a width of the seal  106  in a deformation direction perpendicular to both the toner transport direction and the moving direction of the shutter  105  when the shutter  105  is not inserted in the opening  109  is greater than a width of the opening  109  in the deformation direction at the front-end portion  106   d , which closes the opening  109  when the shutter  105  is at the above-described open position. The width of the seal  106  is substantially equal to the width of the opening  109  at the rear-end portion  106   f , which closes the opening  109  when the shutter  105  is at the closed position. Such configuration allows the seal  106  and the inner wall of the opening  109  to closely contact each other at the front-end portion  106   d . Thus, the sealability of the shutter  105  against the opening  109  is prioritized and the width of the rear-end portion  106   f  of the shutter  105  is substantially equal to the width of the opening  109 , thereby providing a good balance between the sealing of the opening  109  and the slidability of the shutter  105 . 
     Further, the seal  106  can prevent gaps from appearing between the shutter  105  and the inner wall of the opening  109  in the toner transport direction t 1 . Accordingly, the toner supply device  100  can reliably open and close the shutter  105  while preventing toner from being scattered from the opening  109 . 
     As described above, the side portions of the shutter  105  in the deformation direction are formed by leaf springs, thereby providing the desired elasticity in the deformation direction (or the width direction of the shutter  105 ) and the desired stiffness in the toner transport direction (or the thickness direction of the shutter  105 ). 
     As described above, the convex portions  105   b  are formed in the side faces of the shutter  105  in the deformation direction (or the width direction of the shutter  105 ), thereby reducing the contact area between the side faces of the shutter  105  and the inner wall of the opening  109 . Such configuration can reduce the frictional force between the side faces of the shutter  105  and the inner wall of the opening  109  generated when the shutter  105  moves between the closed position and the open position, thereby enhancing the slidability of the shutter  105 . 
     As described above, the seal  106  is elastically deformable and is provided to at least one face of upstream-side and downstream-side faces of the shutter  105  in the toner transport direction. Such configuration can provide relatively high operability compared to a configuration in which the seal  106  is provided on the opening  109  or any other portion in the body of the image forming apparatus. 
     As described above, the middle portion of the seal  106  is narrower than the shutter  105  in the deformation direction. Accordingly, the seal  106  is not in contact with the inner wall of the opening  109 , thereby providing excellent slidability of the shutter  105 . 
     As described above, the toner supply device  100  includes the film member  106   b  covering the seal  106 . The cutout portion  106   c  is formed in the middle portion of the film member  106   b  in the deformation direction, thereby preventing the film member  106   b  from being deformed in a wavy form due to deformation of the shutter  105  in the deformation direction (the width direction of the shutter  105 ). Accordingly, the toner supply device  100  can prevent gaps from appearing between the seal  106  covered with the film member  106   b  and the inner wall of the opening  109  due to wavy deformation of the film member  106   b.    
     As described above, the seal member  107  is provided on a face (hereinafter an “opposite face”) of the shutter  105  opposite to the face on which the seal  106  is provided. The seal member  107  does not entirely cover the opposite face. In other words, the shutter  105  includes a portion in which sealability is prioritized over slidability, i.e., the seal member  107  is closely contacted with the inner wall of the opening  109  so as to reliably prevent toner leak and another portion in which slidability is prioritized, i.e., the seal member  107  is not contacted against the inner wall of the opening  109 . Such configuration can provide excellent balance between the sealing of the opening  109  and the slidability of the shutter  105 . 
     As described above, the vertical grooves  115   c  are provided in the lateral side faces of the shutter  105  in the deformation direction (or the width direction of the shutter  105 ), thereby allowing toner incorporated in a space between the side faces of the shutter  105  and the inner wall of the opening  109  to escape via the grooves  115   c . Such configuration can prevent toner from clogging the space between the side faces and the inner wall, thereby suppressing degradation of the slidability of the shutter  105 . 
     As described above, the image forming apparatus  1000 , which is described taking as a copier an example, includes the photoconductors  1  serving as the latent image carriers to carry a latent image, and the developing device  200  serving as the developing unit to develop the latent image on the photoconductor  1 . Further, the image forming apparatus  1000  includes the toner supply device  100  serving as the toner supply unit, thereby allowing the shutter  105  to be reliably opened and closed when the toner supply device  100  is mounted in and detached from the image forming apparatus  1000 . Such configuration can prevent toner from being scattered from the opening  109 , thereby preventing toner from contaminating the image forming apparatus and/or its surrounding area. 
     It is to be noted that although in the above-described exemplary embodiment the seal  106  for filling gaps between the upper face of the shutter  105  and the opening  109  is provided to the upper face of the shutter  105 , alternatively the seal  106  may be provided to the inner face of the opening  109  or any other suitable portion in accordance with the configuration of the shutter  105 . 
     Exemplary embodiments being thus described, it should be apparent to one skilled in the art after reading this disclosure that the examples and embodiments may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and such modifications are not excluded from the scope of the following claims.