Abstract:
A developer cartridge includes an inner casing, an outer casing, a sealing member, an inner protrusion and an outer protrusion. The inner casing is configured, to accommodate toner therein, the inner casing having a circular cylindrical shape whose axis extends in an axial direction, the inner casing being formed with an inner opening, the inner casing having an outer peripheral surface defining a circumferential direction. The outer casing is configured to accommodate the inner casing therein, the outer casing having a circular cylindrical shape and being formed with an outer opening, the outer casing and the inner casing being capable of rotating relative to each other between a first position where the inner opening and the outer opening are in communication with each other and a second position where the outer casing covers the inner opening. The sealing member is elastically deformable and is provided on the outer peripheral surface of the inner casing and surrounds the inner opening. The inner protrusion protrudes from the outer peripheral surface of the inner casing toward the outer casing. The outer protrusion protrudes from the outer casing toward the inner casing, and serves to maintain a prescribed gap between the inner casing and the outer casing, the outer protrusion being in separation from the inner protrusion in the circumferential direction at the first position, and the outer protrusion being in riding contact with the inner protrusion at the second position to displace the outer casing toward the inner opening and to elastically squash the sealing member between the inner casing and the outer casing in the second position.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Japanese Patent Application No. 2009-109703 filed Apr. 28, 2009, The entire content of the priority application is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a developer cartridge that accommodates developer (developing agent) therein. 
       BACKGROUND 
       [0003]    Conventionally, a developer cartridge is detachably mounted on a developing device that is used in an image forming device. The developer cartridge accommodates developer therein and supplies the developer to the developing device when mounted thereon. One of such conventional developer cartridges includes an inner casing and an outer casing, both of which have a hollow cylindrical shape. The inner casing is formed with an inner opening and the outer casing is formed with an outer opening. The outer casing accommodates the inner casing such that relative rotation can be attained between the inner casing and the outer casing. 
         [0004]    In this developer cartridge, the developer is supplied to the developing device through the inner opening and the outer opening which are in coincidence with and in communication with each other as a result of relative rotation between the inner casing and the outer casing. Also, a sealing member is provided between the inner and outer casings and at a position around the inner opening so that the developer cannot leak from a gap between the outer casing and the inner casing. 
       SUMMARY 
       [0005]    In the above-described developing cartridge, the outer circumferential surface of the inner casing is almost entirely in contact with the inner circumferential surface of the outer casing. Hence, when the relative rotation is provided between the casings, relatively great sliding contact resistance is generated between the inner casing and the outer casing, making the relative rotation difficult. 
         [0006]    In order to reduce the sliding contact resistance at the time of the relative rotation, a sufficient gap may be provided between the inner casing and the outer casing. However, such a configuration may possibly lead to a leakage of the developer from the gap between the inner and outer casings, since the inner casing moves within the outer casing due to vibrations and/or impacts that occur while the developer cartridge is being carried. 
         [0007]    In view of the foregoing, it is an object of the present invention to provide a developer cartridge capable of suppressing developer from leaking between an inner casing and an outer casing, yet facilitating rotation of one casing relative to the other. 
         [0008]    In order to attain the above and other objects, there is provided a developer cartridge including an inner casing, an outer casing, a sealing member, an inner protrusion, and an outer protrusion. The inner casing is configured to accommodate toner therein, the inner casing having a circular cylindrical shape whose axis extends in an axial direction, the inner casing being formed with an inner opening, the inner casing having an outer peripheral surface defining a circumferential direction. The outer casing is configured to accommodate the inner casing therein, the outer casing having a circular cylindrical shape and being formed with an outer opening, the outer casing and the inner casing being capable of rotating relative to each other between a first position where the inner opening and the outer opening are in communication with each other and a second position where the outer casing covers the inner opening. The sealing member is provided on the outer peripheral surface of the inner casing and surrounding the inner opening, the sealing member being elastically deformable. The inner protrusion protrudes from the outer peripheral surface of the inner casing toward the outer casing. The outer protrusion protrudes from the outer casing toward the inner casing, and serving to maintain a prescribed gap between the inner casing and the outer casing, the outer protrusion being in separation from the inner protrusion in the circumferential direction at the first position, and the outer protrusion being in riding contact with the inner protrusion at the second position to displace the outer casing toward the inner opening and to elastically squash the sealing member between the inner casing and the outer casing in the second position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    In the drawings: 
           [0010]      FIG. 1  is s cross-sectional view of a printer according to a first embodiment of the present invention, in which a process cartridge including a toner box according to the first embodiment is mounted in the printer; 
           [0011]      FIG. 2A  is a perspective view of the toner box according to the first embodiment, the toner box including an inner casing and an outer casing those providing an open state; 
           [0012]      FIG. 2B  is a perspective view of the toner box according to the first embodiment, in which the toner box is in a closed state; 
           [0013]      FIG. 3A  is a perspective view of the inner casing according to the first embodiment, as viewed from a direction to observe inner openings; 
           [0014]      FIG. 3B  is a perspective view of the inner casing according to the first embodiment as viewed from a different direction to observe inner protrusions: 
           [0015]      FIG. 4  is a cross-sectional view of the toner box according to the first embodiment taken along a line X-X shown in  FIG. 2A ; 
           [0016]      FIG. 5A  is a cross-sectional view of the process cartridge according to the first embodiment, in which the toner box is in the open state; 
           [0017]      FIG. 5B  is a cross-sectional view of the process cartridge according to the first embodiment, in which the toner box is in the closed state; 
           [0018]      FIG. 6A  is a cross-sectional view of the toner box according to the first embodiment, in which the outer casing is angularly rotated by a rotational angle A 2  from the open state; 
           [0019]      FIG. 6B  is a cross-sectional view of the toner box according to the first embodiment, in which the outer casing is angularly rotated, by a rotational angle A 1  from the open state; 
           [0020]      FIG. 6C  is a cross-sectional view of the toner box according to the first embodiment, in which the outer casing is angularly rotated to the closed state from the open state; 
           [0021]      FIG. 7A  is a perspective view of an inner casing according to a first modification to the first embodiment, in which each part of each inner protrusion spans within a region W 1 ; 
           [0022]      FIG. 7B  is a perspective view of an inner casing according to a second modification to the first embodiment, in which a single inner protrusion spans across a region W 2 ; 
           [0023]      FIG. 7C  is a perspective view of an inner casing according to a third modification to the first embodiment, in which each inner protrusion is located outside of the region W 1 ; 
           [0024]      FIG. 8A  is a cross-sectional view of a toner box according to a second embodiment, in which the toner box is in the open state; 
           [0025]      FIG. 8B  is a cross-sectional view of the toner box according to the second embodiment, in which the toner box is in the closed state; 
           [0026]      FIG. 9A  is a perspective view of an inner casing constituting the toner box according to the second embodiment, as viewed from a direction to observe inner openings; and 
           [0027]      FIG. 9B  is a perspective view of the inner casing according to the second embodiment as viewed from a different direction to observe inner protrusions. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    First, a general configuration of a laser printer  1  according to a first embodiment of the present invention will be described first with reference to  FIG. 1 . In the following description, orientations of the laser printer  1  will be referred to assuming that the laser printer  1  is disposed in an orientation in which it is intended to be used. More specifically, the right side of the laser printer  1  in  FIG. 1  will be referred to as the “front side,” the left side of the laser printer  1  in  FIG. 1  will be referred to as the “rear side,” the near side of the laser printer  1  in  FIG. 1  will be referred to as the “left side,” and the far side of the laser printer  1  in  FIG. 1  will be referred to as the “right side.” Further, the top-to-bottom direction in  FIG. 1  will be referred to as the “vertical direction”. 
         [0029]    The laser printer  1  has a main casing  2  within which a feeder unit  3 , an exposure unit  4 , a process cartridge  5  and a fixing unit  8  are disposed, as shown in  FIG. 1 . The main casing  2  is provided with a front cover  21  at a front side thereof. The main casing  2  has an upper surface on which a discharge tray  22  is formed. 
         [0030]    The feeder unit  3  is disposed at a position lowermost within the main casing  2 . The feeder unit  3  includes a sheet tray  31 , a lifter plate  32  and a plurality of rollers  33 . The sheet tray  31  accommodates sheets P in a stacked state. The lifter plate  32  lifts the sheets P accommodated in the sheet tray  31  upward to allow the sheets P to reach the rollers  33 . The plurality of rollers  33  separate the sheets P one by one, remove paper dusts from each sheet P, and convey each sheet P to the process cartridge  5 . 
         [0031]    The exposure unit  4  is disposed at a position uppermost within the main casing  2 . The exposure unit  4  includes a laser source (not shown), a polygon mirror  41 , lenses  42  and  43 , and reflection mirrors  44 ,  45  and  46 . A laser beam emitted from the laser source based on image data is reflected by or passes through the polygon mirror  41 , the lexis  42 , the reflection mirrors  44  and  45 , the lens  43  and the reflection mirror  46  in this order, and is finally irradiated onto a photosensitive drum  61  (to be described later) at a high speed, as indicated by a chain line in  FIG. 1 . 
         [0032]    The process cartridge  5  is disposed below the exposure unit  4 . The process cartridge  5  is detachably mountable in the main casing  2  when the front cover  21  is opened. The process cartridge  5  includes a photosensitive cartridge  6 , a developing cartridge  7  and a toner box  100 . 
         [0033]    The photosensitive cartridge  6  includes the photosensitive drum  61 , a charger  62  and a transfer roller  63 . The developing cartridge  7  is detachably mountable on the photosensitive cartridge  6 , and includes a developing roller  71 , a supply roller  72  and a thickness regulation blade  73 . 
         [0034]    The toner box  100  is detachably mountable on the developing cartridge  7 . This means that the toner box  100  partly constitutes the process cartridge  5  and the toner box  100  is detachably mountable in the main casing  2  as a part of the process cartridge  5 . The toner box  100  defines therein a toner accommodation chamber  114 . A detailed configuration of the toner box  100  will be described later. 
         [0035]    The photosensitive dram  61  has a surface that is uniformly charged by the charger  62 . After being charged, the surface of the photosensitive drum  61  is exposed to light by the laser beam emitted from the exposure unit  4 , thereby forming an electrostatic latent image on the surface of the photosensitive drum  61  based on the image data. In the meantime, the toner within the toner accommodation chamber  114  is supplied to the developing roller  71  via the supply roller  72 , enters between the developing roller  71  and the thickness regulation blade  73 , and is carried on the developing roller  71  as a thin layer of uniform thickness. 
         [0036]    The toner borne on the developing roller  71  is then supplied to the electrostatic latent image formed on the surface of the photosensitive drum  61  as the developing roller  71  rotates. In this way, the electrostatic latent image is made into a visible toner image on the surface of the photosensitive drum  61 . When the sheet P passes between the photosensitive drum  61  and the transfer roller  63 , the toner image on the surface of the photosensitive drum  61  is transferred to the sheet P. 
         [0037]    The fixing unit  8  is disposed rearward of the process cartridge  5 . The fixing unit  8  includes a heat roller  81 , a pressure roller  82 , and conveyor rollers  83 . The heat roller  81  applies heat to the sheet P, while the pressure roller  82  nips the sheet P together with the heat roller  81  when the sheet P passes between the heat roller  81  and the pressure roller  82 . In this way, the toner image transferred on the sheet P is thermally fixed while the sheet P passes between the heat roller  81  and the pressure roller  82 . The sheet P is finally discharged out of the main casing  2  onto the discharge tray  22  by the conveyor rollers  83  and a pair of discharge rollers  23  provided on the main casing  2 . 
         [0038]    Next, a detailed configuration of the toner box  100  will be described with reference to  FIGS. 2A through 5B . 
         [0039]    As shown in  FIGS. 2A and 2B , the toner box  100  includes an inner casing  110  and an outer casing  120 . The outer casing  120  accommodates the inner casing  110  therein such that relative rotation can occur between the inner casing  110  and the outer casing  120 . The toner box  100  includes the toner accommodation chamber  114  that accommodates toner therein, as shown in  FIGS. 1 and 4 . 
         [0040]    More specifically, the inner casing  110  has a circular cylindrical shape, and includes a circumferential wall section  111  and two side walls  112  and  113 . The circumferential wall section  111  has widthwise ends in a longitudinal direction thereof (i.e. the left-to-right direction) which are covered with the side walls  112  and  113 . In other words, the circumferential wall section  111  and the side walls  112  and  113  define the toner accommodation chamber  114 , as shown in  FIG. 4 . 
         [0041]    The circumferential wail section  111  is formed with three inner openings  115  that are aligned in the longitudinal direction of the inner casing  110 . Each inner opening  115  has a rectangular shape in a plan view. The three inner openings  115  are arranged on the circumferential wall section  111  such that, one is located at a center with respect to the longitudinal direction of the circumferential wall section  111 , and the remaining two inner openings  115  are symmetrically positioned about the center-positioned inner opening  115  in the longitudinal direction. 
         [0042]    The circumferential wall section  111  has an outer circumferential surface  111 A on which three sealing members  116  and three inner protrusions  117  are provided, as shown in  FIGS. 3A and 3B . The sealing member  116  is formed of an elastic material, such as urethane foam, and has a substantially rectangular frame shape with which an opening  116 C is formed. Each sealing member  116  surrounds each of the inner openings  115 . The sealing member  116  contacts an inner circumferential surface  121 A of the outer casing  120  (to be described later), serving to prevent the toner from leaking between the inner casing  110  and the outer casing  120 . 
         [0043]    The inner protrusion  117  radially outwardly protrudes from the outer circumferential surface  111 A of the circumferential wall section  111  (i.e., in a direction toward the outer casing  120 ). The inner protrusion  117  is formed in a substantially trapezoidal shape in a side view and has a top surface on which a recess  117 A is formed. The recess  117 A formed on the top surface has a substantially arucate shape when viewed in the radial direction. As shown in  FIG. 4 , the inner protrusion  117  has such a height in the radial direction so that the top surface slidably contacts the inner circumferential surface  121 A of the outer casing  120  when the inner casing  110  and the outer casing  120  are relatively rotated to each other. The inner protrusion  117  is also formed with a sloped surface  117 B that slopes diagonally outward from the outer circumferential surface  111 A to the top surface with respect to the radial direction. 
         [0044]    As shown in  FIG. 4 , the inner casing  110  has an axis C extending in the longitudinal direction. The inner protrusion  117  is disposed at a diametrically opposite side to the sealing member  116  with respect to the axis C. More specifically, the sealing member  116  has a first end  116 A and a second end  116 B in a circumferential direction of the inner casing  110 . Here, a plane PA is defined as a plane passing the first end  116 A and the axis C, while a plane PB is defined as a plane passing the second end  116 B and the axis C. The inner protrusion  117  is disposed at a position opposite to the sealing member  116  with respect to the axis C and in a region between the planes PA and PB on the outer circumferential surface  111 A. Hereinafter, the longitudinal direction of the inner casing  110  will also be referred to as the “axial direction.” 
         [0045]    Corresponding to the inner openings  115 , the three inner protrusions  117  are arranged such that, one is positioned at a center of the outer circumferential surface  111 A with respect to the axial direction and the other two protrusions  117  are symmetrically positioned about the central protrusion  117  in the axial direction. More specifically, here, a region W 1  is defined as a length and the position of the sealing member  116  in the axial direction, as shown in  FIGS. 3A and 3B . Each inner protrusion  117  is positioned and has a length in the axial direction the same as those of the regions W 1  of the sealing member  116 . 
         [0046]    As shown in  FIG. 4 , an agitator  114 A is disposed within the toner accommodation chamber  114 . The agitator  114 A rotates in a clockwise direction in  FIG. 4  upon receipt of driving force transmitted from a motor (now shown) provided within the main casing  2 . In accordance with the rotation of the agitator  114 A, toner within the toner accommodation chamber  114  is agitated and is conveyed to the inner opening  115 . 
         [0047]    The outer casing  120  includes a circumferential wall section  121  and two side wall sections  122  and  123 , as shown in  FIGS. 2A and 2B . The circumferential wall section  121  has a circular cylindrical shape. The circumferential wall section  121  has the inner circumferential surface  121 A within which the inner casing  110  is accommodated. The circumferential wall section  121  has widthwise ends in the axial direction which are covered with the side wall sections  122  and  123 . The side wall sections  122  and  123  support the inner casing  110  such that the inner casing  110  and the outer casing  120  are relatively rotatable to each other. 
         [0048]    The circumferential wall section  121  is formed with three outer openings  125  that are aligned in the axial direction. Each outer opening  125  has a substantially rectangular shape in a plan view and is disposed at a position coincident with each inner opening  115  formed on the inner casing  110 . More specifically, three outer openings  125  are formed such that, one is positioned at a center of the circumferential wall section  121  with respect to the axial direction and the other two outer openings  125  are symmetrically positioned about the central outer opening  125  in the axial direction. 
         [0049]    As shown in  FIG. 2A , when the inner opening  115  and the outer opening  125  are in coincident with each other as a result of relative rotation between the inner and outer casings  110 ,  120 , the inner opening  115  and the outer opening  125  are in communication with each other and, therefore, the toner accommodated within the toner accommodation chamber  114  is supplied to the developing cartridge  7  via the inner opening  115  and the outer opening  125 . At this time, the toner box  100  is called to be in the “open state.” Contrary, as shown in  FIG. 2B , when inner casing  110  and the outer casing  120  are relatively rotated to each other from the open state, the inner opening  115  is covered with the circumferential wail section  121  of the outer casing  120 , enabling the circumferential wall section  121  to serve as a shutter to close the inner opening  115 . The toner box  100  at this time is called to be in the “closed state.” In this way, the inner casing  110  and the outer casing  120  are rotatable relative to each other between the open state and the closed state. 
         [0050]    As shown in  FIG. 4 , the outer casing  120  accommodates the inner casing  110  therein such that a prescribed gap is provided therebetween. More specifically, when the toner box  100  is in the open state, the sealing members  116  and the inner protrusions  117  of the inner easing  110  are respectively in contact with the inner circumferential surface  121 A of the outer casing  120 , thereby enabling the inner casing  110  to be maintained within the outer casing  120  in such a state that the prescribed gap can be formed between the inner circumferential surface  121 A and the outer circumferential surface  111 A. 
         [0051]    The outer casing  120  has three outer protrusions  127  that radially inwardly protrude (i.e., toward the inner casing  110 ) from the inner circumferential surface  121 A of the circumferential wail section  121 . Each outer protrusion  127  has a substantially semi-circular columnar shape. The three outer protrusions  127  are arrayed in the axial direction, and are disposed such that, one is positioned at a center of the inner circumferential surface  121 A with respect to the axial direction, and the other two outer protrusions  127  are symmetrically positioned about the central outer protrusion  127  in the axial direction. In this way, the outer protrusions  127  are configured to be in coincident with the inner protrusions  117  when the inner casing  110  and the outer casing  120  rotate relative to each other. Further, each outer protrusion  127  has a length in the axial direction substantially identical to the length of the sealing member  116  within the region W 1 . 
         [0052]    To provide the closed state from the open state, as shown in  FIG. 4 , when the outer casing  120  is made to rotate relative to the inner casing  110  about the axis C in the clockwise direction, by a rotational angle A 1 , the outer protrusion  127  contacts the inner protrusion  117 . In the mean time, the outer casing  120  covers the opening  116 C of the sealing member  116  by rotating about the axis C by a rotational angle A 2 . As apparent from  FIG. 4 , the rotational angle A 1  is greater than the rotational angle A 2  in the present embodiment. 
         [0053]    As shown in  FIGS. 2A and 2B , each side wail section  122  ( 123 ) is formed with an operation portion  128  and a pair of engaging protrusions  129 . The operation portion  128  is used when a user rotates the inner casing  110  and the outer casing  120  relative to each other between the open state and the closed state. The engaging protrusions  129  are configured to engage a shutter  75  ( FIGS. 5A and 5B ) of the developing cartridge  7  (to be described next) when the toner box  100  is mounted on the developing cartridge  7 . 
         [0054]    Referring to  FIGS. 5A and 5B , the developing cartridge  7  includes a developing frame  70  and the shutter  75 . The developing frame  70  defines therein a developing chamber  74  within which the developing roller  71  and the supply roller  72  are disposed. The developing frame  70  is also formed with a port  70 A that introduces toner to the developing chamber  74  from the toner accommodation chamber  114 . The shutter  75  has a substantially arcuate shape in cross-section, following a contour of the outer casing  120  of the toner box  100 . The shutter  75  has an aperture  75 A. The shutter  75  is movably supported to the developing frame  70  such that the shutter  75  can close or open the port  70 A. Specifically, the shutter  75  is movable between a position where the aperture  75 A is aligned with the port  70 A, to open the port  70 A so that the developing chamber  74  and the toner accommodation chamber  114  can be in communication with each other ( FIG. 5A ), and a position where the port  70 A is closed so as not to allow the toner to be introduced from the toner accommodation chamber  114  to the developing chamber  74  ( FIG. 5B ). 
         [0055]    The shutter  75  is formed with openings or cutouts adapted to engage the engaging protrusions  129  of the outer casing  120  when the toner box  100  is mounted on the developing cartridge  7 . As the user moves the operation portion  128 , the outer casing  120  angularly rotates relative to the inner casing  110 , and the toner box  100  becomes the open state. In conjunction with the rotation of the outer casing  120 , the shutter  75 , which is in engagement with the engaging protrusions  129 , is made to move to the position shown in  FIG. 5A , thereby opening the port  70 A for allowing the developing chamber  74  and the toner accommodation chamber  114  to be communicable. 
         [0056]    When the toner box  100  is mounted on the developing cartridge  7 , the side walls  112  and  113  of the inner casing  110  are in engagement with the developing frame  70  of the developing cartridge  7 , restricting the inner casing  110  from rotating relative to the developing frame  70 . Hence, in the present embodiment, the outer casing  120  is configured to rotate relative to the inner casing  110  when the user manipulates the operation portion  128 . A sealing member  76  is provided between the developing frame  70  and the shutter  75 . The sealing member  76  surrounds the port  70 A for preventing toner from leaking between the developing frame  70  and the shutter  75 . 
         [0057]    Next, operations to make the outer casing  120  rotate relative to the inner casing  110  from the open state to the closed state will be described with reference to  FIGS. 4 through 6C . 
         [0058]    In the open state, the outer protrusion  127  and the inner protrusion  117  are at separated positions from each other with respect to the circumferential direction of the inner easing  110 , as shown in  FIGS. 4 and 5A . 
         [0059]    In order to rotate the outer easing  120  from the open state ( FIGS. 4 and 5A ) to the closed state ( FIG. 5B ), the user needs to move the operation portion  128  in a counterclockwise direction in  FIG. 5A . Hereinafter, the direction in which the outer casing  120  rotates will be referred to as the “rotational direction.” 
         [0060]    Referring to  FIG. 6A , for the sake of explanation, a periphery of the outer opening  125  located rearward in the rotational direction will be referred to as the rear periphery  125 A. Also, referring to  FIG. 4 and 6A , the sealing member  116  is assumed to have a front portion  116 F and a rear portion  116 R, the front portion  116 F being located forward of the rear portion  116 R in the rotational direction with the opening  116 C interposed therebetween. 
         [0061]    In  FIG. 6A , while the outer casing  120  is made to rotate by the rotational angle A 2 , the rear periphery  125 A passes the inner opening  115  and contacts the front portion  116 F of the sealing member  116 . In this way, the outer casing  120  (the circumferential wall section  121 ) covers the opening  116 C (the inner opening  115 ). In the present embodiment, the rotational angle A 1  is made greater than the rotational angle A 2 . Therefore, at the time when the outer casing  120  covers the opening  116 C, the inner protrusion  117  and the outer protrusion  127  have not yet been in contact with each other. 
         [0062]    Subsequently, when the outer casing  120  is further rotated by the rotational angle A 1 , the inner protrusion  117  (the sloped surface  117 B) and the outer protrusion  127  are brought into contact with each other, as shown in  FIG. 6B . At this time, the rear periphery  125 A of the outer opening  125  has also moved by the rotational angle A 1 , and therefore the rear periphery  125 A (the circumferential wail section  121 ) and the sealing member  116  partially overlap with each other. 
         [0063]    From the state shown in  FIG. 6B , when the outer casing  120  is made to rotate further forward in the rotational direction, the outer protrusion  127  climbs the sloped surface  117 B, making the outer protrusion  127  and the inner protrusion  117  slidingly contact with each other. When the outer protrusion  127  finally climbs up to reach the top surface of the inner protrusion  117  and engages the recess  117 A, the outer casing  120  is in the closed state, as shown in  FIG. 6C . 
         [0064]    While the outer protrusion  127  climbs up the sloped surface  117 B and slidingly contacts the inner protrusion  117 , the outer casing  120  is gradually urged to move closer to the inner opening  115  as indicated by an arrow in  FIG. 6C . When the outer protrusion  127  is in engagement with the recess  117 A, the outer casing  120  and the inner opening  115  are to have a distance closest to each other (the gap between the inner casing  110  and the outer casing  120  becomes smallest in the vicinity of the inner opening  115 ). 
         [0065]    In the above-described process, the elastic sealing member  116  is gradually pressed by the outer casing  120 , and is eventually, in the closed state, squashed between the outer casing  120  and the inner casing  110  around the inner opening  115 . In this way, the sliding contact resistance between the inner casing  110  and the outer casing  120  becomes greater, making relative rotation between the inner casing  110  and the outer casing  120  difficult. 
         [0066]    As shown in  FIGS. 6A and 6B , until the outer protrusion  127  contacts the inner protrusion  117 , the inner protrusion  117  (the top surface of the inner protrusion  117 ) slidingly contacts the inner circumferential surface  121 A of the outer casing  120  in accordance with the rotation of the outer casing  120 . With this configuration, the gap between the inner casing  110  and the outer casing  120  can be maintained so that the sliding contact resistance at the time of rotation can be suppressed low, thereby facilitating the user&#39;s operation to rotate the outer casing  120 . 
         [0067]    As above-described, the outer casing  120  can accommodate the inner casing  110  therewithin such that the inner casing  110  and the outer casing  120  can rotate relative to each other while the gap is kept therebetween. Therefore, the user can rotate the outer casing  120  easily relative to the inner casing  110  since there is small sliding contact resistance generated at the time of rotating the outer casing  120 . 
         [0068]    Further, in the closed state, as the outer protrusion  127  climbs up the sloped surface  117 B and in contact with the top surface of the inner protrusion  117 , the outer casing  120  is brought closer to the inner opening  115 , thereby pressing and squashing the sealing member  116  between the inner casing  110  and the outer casing  120 . Hence, the inner casing  110  can be made resistant to the relative rotation against the outer casing  120 . This configuration can prevent toner leakage from the toner box  100  during transportation thereof. 
         [0069]    Further, the rotational angle A 1  by which the outer casing  120  rotates until the outer protrusion  127  contacts the inner protrusion  117  is greater than the rotational angle A 2  by which the outer casing  120  rotates until the outer casing  120  covers the opening  116 C of the sealing member  116  in the present embodiment. Therefore, the rear periphery  125 A of the outer opening  125  can be reliably overlapped with the sealing member  116  before the outer easing  120  is in the closed state where the inner opening  115  is closest to the outer casing  120 . In this way, the inner opening  115  is covered with the outer casing  120  with the shortest gap therebetween. 
         [0070]    Suppose that the rotational angle A 1  is smaller than the rotational angle A 2 . In this case, when the outer casing  120  is made to rotate by the rotational angle A 1 , the outer protrusion  127  contacts the inner protrusion  117 . When the outer casing  120  rotates further in the rotational direction, the outer protrusion  127  climbs up the sloped surface  117 B and slidingly contacts the top surface of the inner protrusion  117 , while the outer casing  120  displaces closer to the inner opening  115 . When the outer casing  120  is further made to rotate by the rotational angle A 2 , the rear periphery  125 A of the outer opening  125  contacts a tip end of the opening  116 C of the sealing member  116 . 
         [0071]    If the outer casing  120  is further made to rotate from this state, the rear periphery  125 A pushes the tip end of the opening  116 C of the sealing member  116  in the rotational direction and may peel the sealing member  116  off from the outer circumferential surface  111 A of the inner casing  110 . In the present embodiment, the rear periphery  125 A of the outer opening  125  and the sealing member  116  can be overlapped with each other before the outer casing  120  is urged to be moved toward the inner opening  115 . Hence, peel-off of the sealing member  116  from the inner casing  110  can be suppressed. 
         [0072]    Further, in the present embodiment, the inner protrusion  117  is provided at a side diametrically opposite to the sealing member  116  with respect to the axis C. With this configuration, the pressing force acting in a direction to squash the sealing member  116  as a result of the contact between the inner protrusion  117  and the outer protrusion  127  can be reliably transmitted to the sealing member  116 . 
         [0073]    Further, the inner protrusions  117  and the outer protrusions  127  are provided symmetrically with respect to the axial center of the casings  110 ,  120 , respectively. Therefore, the pressing force acting on the sealing member  116  can be generated uniformly in the axial direction. 
         [0074]    Further, each inner protrusion  117  and each outer protrusion  127  are respectively provided within the region W 1  within which each sealing member  116  is provided in the axial direction. Therefore, the pressing force that acts to squash the sealing member  116  can be transmitted to the sealing member  116  more reliably. 
         [0075]    As described, the present embodiment enables the pressing force to be reliably transmitted to the sealing member  116  as well as to be uniform in the axial direction. Therefore, in the closed state, there is generated little gap between the squashed sealing member  116  and the outer casing  120  (the inner circumferential surface  121 A), surely preventing the toner from leaking outside. 
         [0076]    Although, in the present embodiment, the three inner protrusions  117  and the three outer protrusions  127  are respectively aligned in the axial direction such that one is at the center and the other two are symmetrically positioned about the central one, the present embodiment is not limited to this configuration. 
         [0077]    For example, two inner protrusions  117  and two outer protrusions  127  may be respectively provided on both sides in the axial direction. Alternatively, not less than four inner protrusions  117  and not less than four outer protrusions  127  may be aligned in the axial direction. 
         [0078]    Further, instead of the present configuration in which the inner protrusion  117  and the outer protrusion  127  are disposed within the region W 1  with a length substantially identical to that of the sealing member  116  in the axial direction, the inner protrusion  117  and the outer protrusion  127  may have a length shorter than that of the sealing member  116  in the axial direction within the region W 1 . 
         [0079]    Alternatively, as shown in  FIG. 7A , at least a portion of the inner protrusion  117  and a portion of the outer protrusion  127  (not shown) may be positioned within the region W 1 , respectively. In this case, a portion of the inner protrusion  117  may span the entire region W 1  as in the central inner protrusion  117 , or a portion of the inner protrusion  117  may partially occupy the region W 1  as in the inner protrusions  117  located on left and right sides. 
         [0080]    Still alternatively, as shown in  FIG. 7B , a single inner protrusion  117  and a single outer protrusion  127  (not shown) may be provided respectively to have a length in the axial direction that spans a region W 2 , the region W 2  being a region between the two outermost sealing members  116  (more specifically, between outer ends of the two outermost sealing members  116 ). With this arrangement, the pressing force acting in the direction to squash the sealing members  116  can be uniform. Therefore, a gap between the squashed sealing members  116  and the outer casing  120  can be almost eliminated, ensuring that toner leakage can be reliably prevented in the closed state. Also, respective lengths of the inner protrusion  117  and the outer protrusion  127  (not shown) in the axial direction may be greater than the region W 2 . 
         [0081]    Further alternatively, as shown in  FIG. 7C , the inner protrusion  117  and the outer protrusion  127  (not shown) may be provided outside of the region W 1 . Note that the portions of the inner casing  110  on which the inner openings  115  are formed and the portions of the outer casing  120  on which the outer openings  125  are formed respectively have a strength weaker relative to other portions of the inner casing  110  and the outer casing  120 . Hence, arranging the inner protrusions  117  and the outer protrusions  127  outside of the region W 1  can ease the pressing force acting on the sealing members  116  provided around the inner openings  115  and the outer openings  125 . With this arrangement, deformation of the inner casing  110  and the outer casing  120  can be suppressed, thereby restraining toner from leaking between the inner casing  110  and the outer casing  120 . The lengths of the inner protrusion  117  and the outer protrusion  127  may be changed appropriately. 
         [0082]    Next, a toner box  100  according to a second embodiment of the present invention will be described with reference to  FIGS. 8A through 9B . Note that, hereinafter, like parts and components are designated by the same reference numerals as those shown in  FIGS. 1 through 7C  to avoid duplicating description. 
         [0083]    As shown in  FIGS. 9A and 9B , the inner casing  110  according to the second embodiment includes the outer circumferential surface  111 A, three sealing members  116 , three inner protrusions  117 ′, and three restricting protrusions  118 . The three restricting protrusions  118  are provided on the outer circumferential surface  111 A such that, all the three restricting protrusions  118  are aligned in the axial direction and each is paired with one of the inner protrusions  117 ′, as shown in  FIG. 9B . 
         [0084]    As shown in  FIGS. 8A and 8B , each restricting protrusion  118  protrudes from the outer circumferential surface  111 A toward the outer casing  120  at a position adjacent to and above the corresponding inner protrusion  117 ′ in  FIG. 8A . The restricting protrusion  118  has a substantially rectangular columnar shape and is provided with a top surface. The restricting protrusion  118  is formed to have such a height that the top surface is in continuous sliding contact with the inner circumferential surface  121 A of the outer casing  120  when the inner casing  110  and the outer casing  120  rotate relative to each other from the open state to the closed state. 
         [0085]    The restricting protrusion  118  is disposed at a side opposite to the sealing member  116  with respect to the axis C. More specifically, the restricting protrusion  118  is provided on the outer circumferential surface  111 A in association with the corresponding inner protrusion  117 ′ at a position opposite to the sealing member  116  with respect to the axis C and in a region interposed between the planes PA and PB. 
         [0086]    Further, as shown in  FIGS. 9A and 9B , three restricting protrusions  118  are provided such that, one is positioned at a center of the circumferential wall section  111  with respect to the axial direction, and the other two are symmetrically positioned about the centrally-positioned restricting protrusion  118  in the axial direction. Each restricting protrusion  118  has a length in the axial direction the same as those of the sealing member  116  and the inner protrusion  117 ′ within the region W 1 . 
         [0087]    The inner protrusion  117 ′ of the second embodiment is different from the inner protrusion  117  of the first embodiment only in that the height of inner protrusion  117 ′ according to the second embodiment is shorter and therefore the top surface of the inner protrusion  117 ′ does not slidingly contact the inner circumferential surface  121 A of the outer casing  120 . The outer casing  120  according to the second embodiment has a configuration identical to that of the first embodiment. 
         [0088]    In the toner box  100  of the second embodiment with the above-described configuration, while the outer casing  120  is made to rotate relative to the inner casing  110  from the open state until the inner protrusion  117 ′ and the outer protrusion  127  contact with each other, the restricting protrusion  118  serves to maintain the gap between the inner casing  110  and the outer casing  120  by slidingly contacting the inner circumferential surface  121 A of the outer casing  120 . At this time, the user can rotate the outer casing  120  easily since there is generated small sliding contact resistance. 
         [0089]    In the second embodiment, the restricting protrusion  118  is provided for an exclusive purpose of maintaining the gap between the inner casing  110  and the outer casing  120 , which means that the height of the inner protrusion  117 ′ can be determined at a greater discretion. Hence, the pressing force acting in the direction to squash the sealing member  116  can also be adjusted appropriately depending on materials of the sealing member  116 , leading to prevention of toner leakage. 
         [0090]    Further, the restricting protrusion  118  is disposed at a side opposite to the sealing member  116  with respect to the axis C. Hence, in the open state, both of the restricting protrusion  118  and the sealing member  116  are in contact with the inner circumferential surface  121 A of the outer casing  120 , and therefore, backlash or rattling of the outer casing  120  relative to the outer casing  110  can be suppressed effectively. 
         [0091]    In the present embodiment, the restricting protrusion  118  is disposed in association with the inner protrusion  117 ′, but the present invention does not limited to this configuration. For example, only one long restricting protrusion  118  may be provided in the axial direction vis-a-vis the three inner protrusions  117 ′ that are aligned in the axial direction. Further, the second embodiment may be applied with modifications the same as those applied to the first embodiment (shown in  FIGS. 7A through 7C ). 
         [0092]    While the invention has been described in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention. 
         [0093]    For example, the inner protrusion  117  ( 117 ′) and the outer protrusion  127  may extend to the axially outermost sides of the circumferential wall section  111  and the circumferential wall section  121  in the axial direction respectively. 
         [0094]    The three inner protrusions  117  ( 117 ′) and three outer protrusions  127  are arranged in the axial direction in association with each other in the above embodiments. However, instead, another configuration may also be employed in which three inner protrusions  117  ( 117 ′) may be aligned in the axial direction, whilst only one long outer protrusion  127  may be arranged in the axial direction. 
         [0095]    In the above-described configuration, referring to  FIG. 4 , the inner casing  110  and the outer casing  120  are in contact with each other at three points in the open state, when seen in the radial direction, by the inner protrusion  117  (or the restricting protrusion  118 ) and the sealing member  116  surrounding the inner opening  115  (more specifically, the front portion  116 F and the rear portion  116 R of the sealing member  116 ). However, the inner casing  110  and the outer casing  120  may be so configured as to contact with each other at more than four points by providing increased number of restricting protrusions  118 . Providing protrusions appropriately for maintaining the gap between the inner casing  110  and the outer casing  120  can facilitate rotating operations performed by the user. 
         [0096]    Further, instead of aligning the three inner openings  115  and the three outer openings  125  in the axial direction such that one at the center and the other two symmetrically about the central one, other arrangements of openings may be possible. 
         [0097]    For example, an elongated single opening extending in the axial direction may be formed, or two openings may be formed, or not less than four openings may be formed. Further, shapes and sizes (length in the axial direction) of the openings may also be changed accordingly. 
         [0098]    As to the sealing members  116 , all the three inner openings  115  are surrounded by the three sealing members  116  in the above embodiments. However, one sealing member that encompasses all the inner openings  115  may be employed instead. In the latter case, the sealing member may be formed with a plurality of openings that corresponds to the number of the formed inner openings  115 . 
         [0099]    Further, the present invention has been described with reference to the laser printer  1  as an example of image forming devices in which the toner box  100  of the present invention is mounted. However, the present invention may also be applicable to other types of image forming devices such as an LED printer, a copier and a multifunction device.