Patent Publication Number: US-9429876-B2

Title: Toner case and image forming apparatus including the same

Description:
TECHNICAL FIELD 
     The present invention relates to a toner case and an image forming apparatus including the same. 
     BACKGROUND ART 
     As disclosed in Patent Document 1, an image forming apparatus, such as a laser printer, includes a toner container as a toner case to be attached to an apparatus main body. The apparatus main body is provided with an image forming portion including a developing portion. 
     The toner container includes a case body in which a toner as a developer is contained. The case body is provided with a toner supplying portion which supplies a toner to the developing portion of the apparatus main body. Further, at an inside of the case body, a screw portion which conveys the toner to the toner supplying portion and a stirring mechanism which stirs the toner are provided. 
     The stirring mechanism includes a shaft driven to rotate at the inside of the case body, and a stirring sheet attached to the shaft. The screw portion includes a screw shaft driven to rotate at the inside of the case body, and a spiral conveying blade formed on an outer face of the screw shaft and elongated along an axial direction of the screw shaft. One end of the screw shaft is rotatably supported by a bearing formed at the inside of the case body. Meanwhile, another end of the screw shaft is supported by a driving member, which transmits a driving force of a motor, at the inside of the case body. 
     Further, the toner contained at the inside of the case body is stirred by the stirring mechanism and is conveyed to the screw portion. The toner having been conveyed to the screw portion is conveyed to the toner supplying portion by the screw portion. Thus, the toner is supplied from the toner supplying portion to the developing portion outside the case body. 
     [Patent Document 1] Japanese Unexamined Patent Application, Publication No. 2010-176033 
     SUMMARY OF INVENTION 
     Technical Problem 
     By the way, at an outside face of a side wall of the toner container, a structure portion, such as a grip portion, which a user grips to attach the toner container to or to detach the toner container from the apparatus main body is formed in some cases. The structure portion, such as the grip portion, is formed integrally with the case body of the toner container by a metal mold. 
     However, when a supporting portion which supports the screw shaft is arranged so as to protrude closer to an outside than the side wall of the case body, it is difficult to form a structure, such as the grip portion, in this side wall, and therefore the flexibility of the design in the outside face of the side wall of the case body lowers in some cases. 
     Further, when the supporting portion and an end portion of the screw shaft are arranged closer to the outside than the side wall of the case body, the supporting portion significantly limits a layout of parts at an apparatus main body side in some cases. 
     By the way, when the supporting portion is arranged closer to an inside than the side wall of the case body, a toner gathered around this supporting portion is not conveyed by the conveying blade of the screw portion, and therefore there is a problem that the toner is likely to be aggregated around the supporting portion. 
     The present invention has been made in light of such a problem, and an object of the present invention is to efficiently convey a toner in the case body by the screw portion while arranging the supporting portion, which supports the screw shaft, closer to the inside than the side wall of the case body. 
     Solution to Problem 
     A toner case according to the present invention includes a case body, a toner supplying portion, a screw portion and a supporting portion. The case body is attached to an apparatus main body of an image forming apparatus and configured to contain a toner. The toner supplying portion is arranged at the case body so as to supply the toner to the apparatus main body. The screw portion includes a screw shaft and a conveying blade. The screw shaft is driven to rotate at an inside of the case body. The conveying blade is formed on the screw shaft and configured to rotate with the screw shaft so that the conveying blade conveys the toner to the toner supplying portion. Around the supporting portion, a portion of the conveying blade is arranged. The supporting portion is arranged closer to an inside of the case body than a side wall of the case body and configured to support an end portion of the screw shaft. 
     An image forming apparatus according to the present invention includes the above-mentioned toner case. 
     Advantageous Effects of Invention 
     The present invention makes it possible to efficiently convey a toner in the case body by the screw portion while arranging the supporting portion, which supports the screw shaft, closer to the inside than the side wall of the case body. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view showing a schematic structure of an image forming apparatus according to the present embodiment. 
         FIG. 2  is a perspective view showing an appearance of an upper part of a toner container according to the present embodiment. 
         FIG. 3  is an exploded perspective view showing a structure of the toner container. 
         FIG. 4  is a perspective view showing an appearance of a bottom portion of the toner container. 
         FIG. 5  is a plan view showing a structure of an inside of a container main body. 
         FIG. 6  is a perspective view showing an appearance of a screw portion. 
         FIG. 7  is an enlarged sectional view showing an end part of the screw portion supported by a bearing. 
         FIG. 8  is an enlarged sectional view showing an end part of the screw portion supported by a driving member. 
         FIG. 9  is an enlarged perspective view showing end parts of the screw portion, respectively. 
         FIG. 10  is an enlarged perspective view showing the end portion of the screw part supported by the bearing. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment of the present invention will be described in detail based on the drawings. Incidentally, the present invention is not limited to the following embodiment. 
     &lt;Laser Printer&gt; 
       FIG. 1  is a sectional view showing a schematic structure of a laser printer  1  as an image forming apparatus according to the present embodiment. 
     As shown in  FIG. 1 , the laser printer  1  includes an apparatus main body  2  and a toner container  21  as a toner case detachably attached to the apparatus main body  2 . 
     The apparatus main body  2  includes a manual paper feeding portion  6 , a cassette paper feeding portion  7 , an image forming portion  8 , a fixing portion  9  and a discharging portion  10 . Thus, the laser printer  1  is configured to form an image on a sheet based on image data transmitted from a terminal or the like which is not shown while conveying the sheet along a conveying path L in the apparatus main body  2 . 
     The manual paper feeding portion  6  includes a manual feeding tray  4  which is openably provided to one side portion of the apparatus main body  2 , and a manual paper feeding roller  5  which is rotatably provided inside the apparatus main body  2 . 
     The cassette paper feeding portion  7  is provided at a bottom portion of the apparatus main body  2 . The cassette paper feeding portion  7  includes a paper feeding cassette  11  which contains a plurality of sheets overlaid on each other, a pick roller  12  which picks the sheets in the paper feeding cassette  11  one by one, and a feeding roller  13  and a retard roller  14  which separate the picked sheets one by one, and feed the sheets to the conveying path L. 
     The image forming portion  8  is provided above the cassette paper feeding portion  7  inside the apparatus main body  2 . The image forming portion  8  includes a photosensitive drum  16  as an image bearing body rotatably provided in the apparatus main body  2 , a charger  17 , a developing portion  18 , a transfer roller  19  and a cleaning portion  20  which are arranged around the photosensitive drum  16 , and a laser scanner unit (LSU)  30  as an optical scanning device arranged above the photosensitive drum  16 . To the developing portion  18 , a toner from a toner container  21  is supplied. Thus, the image forming portion  8  forms an image on a sheet supplied from the manual paper feeding portion  6  or the cassette paper feeding portion  7 . 
     Incidentally, the conveying path L is provided with a pair of resist rollers  15  which supply a conveyed sheet to the image forming portion  8  at a predetermined timing after making the sheet temporarily stand by. 
     The fixing portion  9  is arranged at a side of the image forming portion  8 . The fixing portion  9  includes a fixing roller  22  and a pressuring roller  23  which come into pressure contact with each other so as to rotate. Thus, the fixing portion  9  is configured to fix a toner image, which is transferred to the sheet by the image forming portion  8 , to the sheet. 
     The discharging portion  10  is provided above the fixing portion  9 . The discharging portion  10  includes a paper eject tray  3 , a pair of discharging rollers  24  which convey sheets to the paper eject tray  3 , and a plurality of conveying guide ribs  25  which guide sheets to a pair of discharging rollers  24 . The paper eject tray  3  is formed in a concave shape at an upper portion of the apparatus main body  2 . 
     When the laser printer  1  receives image data, in the image forming portion  8 , the photosensitive drum  16  is driven to rotate, and the charger  17  charges the face of the photosensitive drum  16 . 
     Further, based on the image data, laser light is emitted from the laser scanner unit  30  to the photosensitive drum  16 . When the face of the photosensitive drum  16  is irradiated with the laser light, an electrostatic latent image is formed on the face of the photosensitive drum  16 . Meanwhile, the developing portion  18  receives a supply of a toner from the toner container  21 . The electrostatic latent image formed on the photosensitive drum  16  is developed by the developing portion  18  as a toner image which becomes a visible image. 
     Subsequently, the sheet is pressed against the face of the photosensitive drum  16  by the transfer roller  19 . Thus, the toner image of the photosensitive drum  16  is transferred to the sheet. The sheet to which the toner image has been transferred is heated and pressured by the fixing roller  22  and the pressuring roller  23  in the fixing portion  9 . As a result, the toner image is fixed to the sheet. 
     &lt;Toner Container&gt; 
       FIGS. 2 to 5  show a configuration of the toner container  21  according to the present embodiment. 
     The toner container  21  is arranged above the image forming portion  8 , for example. As shown in  FIGS. 2 to 5 , the toner container  21  includes a case body  31  in which a toner is contained and which is attached to the apparatus main body  2 , a toner supplying portion  32  which is arranged at the case body  31  so as to supply a toner to the apparatus main body  2 , a stirring mechanism  40  which stirs the toner at the inside of the case body  31 , and a screw portion  50  which conveys the toner to the toner supplying portion  32 . 
     The case body  31  includes a bottomed container body  35  whose upper portion is opened, and a lid portion  36  which covers the opened portion of the container body  35 . The container body  35  includes a bottom portion  37  which includes an inner wall face whose cross section has an arc shape. 
     As shown in  FIG. 4 , at a side wall  31   a  of the case body  31 , a grip portion  44  which a user grips to attach the toner container  21  to or detach the toner container  21  from the apparatus main body  2  is formed to protrude to an outside of the case body  31 . 
     Meanwhile, as shown in  FIGS. 3 and 4 , at a side wall  31   b  opposing to the side wall  31   a  at which the grip portion  44  is formed, a positioning member  45  which positions the case body  31  to an apparatus main body  2  side is formed so as to protrude to the outside of the case body  31 . 
     As shown in  FIG. 3 , the stirring mechanism  40  is attached to the container body  35 . The stirring mechanism  40  includes a shaft  41  which is driven to rotate at the inside of the case body  31 , and a stirring sheet  42  which is attached to the shaft  41 . 
     The case body  31  extends along the shaft  41 . One end of the shaft  41  is rotatably supported by the container body  35 . Meanwhile, another end of the shaft  41  is coupled to a driving coupling portion  43  arranged outside the container body  35 . Thus, the shaft  41  is driven to rotate by a driving force transmitted via the driving coupling portion  43 . 
     The stirring sheet  42  is composed of a sheet member having an elasticity, and is made of a plastic film, for example. The stirring sheet  42  is formed in a rectangular shape, and has a long side portion fixed to the shaft  41 . Further, another long side portion of the stirring sheet  42  which is not fixed to the shaft  41  moves while coming into contact with an inner wall face of at least the bottom portion  37  of the case body  31  in a rotating state of the shaft  41 . Thus, the toner in the case body  31  is stirred by the stirring sheet  42  which is rotated with the shaft  41 . 
     The screw portion  50  is arranged to be elongated along the shaft  41  at the inside of the case body  31 . Further, the screw portion  50  is arranged above a lowermost position of the bottom portion  37  of the case body  31 . Furthermore, the screw portion  50  is configured to rotate to convey a toner in the axial direction of the screw portion  50 . 
     Still further, the container body  35  which is a toner conveying destination of the screw portion  50  is provided with a toner discharge outlet  32   a  and a shutter  32   b  as a toner supplying portion  32 . As shown in  FIG. 5 , the toner discharge outlet  32   a  is provided at a position biased to a left side in  FIG. 5  in the case body  31 , for example. 
     Thus, when the shaft  41  of the stirring mechanism  40  is driven to rotate, the stirring sheet  42  is rotated while coming into contact with the inner wall surface of the bottom portion  37  of the container body  35 . Thus, the toner of the bottom portion  37  of the case body  31  is scooped up toward the screw portion  50  while being stirred by the stirring sheet  42 . Next, the toner is conveyed to the toner supplying portion  32  by the rotating screw portion  50 . Further, the toner having arrived at the toner supplying portion  32  is supplied to the developing portion  18  of the apparatus main body  2  of the laser printer  1 . 
     Next, the screw portion  50  and a supporting structure of the screw portion  50  will be described in detail. 
     As shown in  FIGS. 5 and 6 , the screw portion  50  includes a screw shaft  51  which extends in parallel to the shaft  41  and is driven to rotate at the inside of the case body  31 , and conveying blade  52  which are formed around the screw shaft  51  and are rotated with the screw shaft  51  to convey the toner to the toner supplying portion  32 . 
     In this regard,  FIGS. 7 and 8  show enlarged vicinities of an end portion of the screw shaft  51 .  FIGS. 9 and 10  show enlarged appearances of the screw portion  50 . As shown in  FIGS. 7 and 8 , the end portion of the screw shaft  51  is supported by a supporting portion  53  formed at the toner container  21 . 
     That is, as shown in  FIG. 7 , one end portion of the screw shaft  51  is rotatably supported by a cylindrical bearing  54  as a supporting portion  53 . The bearing  54  is arranged closer to an inside of the case body  31  than the side wall  31   a  of the case body  31 , and is formed so as to protrude from the side wall  31   a  of the case body  31  to the inside of the case body  31 . 
     Meanwhile, as shown in  FIGS. 8 and 9 , at the other end portion of the screw shaft  51 , a cylinder portion  51   a  which extends in the axial direction of the screw shaft  51  is formed. The cylinder portion  51   a  of the screw shaft  51  is externally fitted to one end portion of a driving member  55  which transmits a driving force to the screw shaft  51 . Further, the driving member  55  includes a claw portion (not shown), and this claw portion engages with an opening portion  51   b  formed on a side face of the cylinder portion  51   a  so as to fix the driving member  55  to the cylinder portion  51   a . Thus, the screw shaft  51  is rotated with the driving member  55 . 
     Further, one end portion of the driving member  55  to which the cylinder portion  51   a  is externally fitted is a first joint portion  55   a  as a supporting portion  53  which supports the end portion of the screw shaft  51 . This first joint portion  55   a  is arranged closer to the inside of the case body  31  than the side wall  31   b  of the case body  31 . 
     In this regard, in the container body  35 , a cylindrical bearing portion  56  which is elongated to the outside of the case body  31  is formed. The driving member  55  includes a cylindrical shaft portion  55   b  which is rotatably supported by an inner circumference face of the bearing portion  56 , the first joint portion  55   a  which is formed at one end side of the shaft portion  55   b , and a second joint portion  55   c  which is formed at another end side of the shaft portion  55   b.    
     Around the shaft portion  55   b  in the case body  31 , a seal member  57  which prevents the toner from scattering to the outside of the case body  31  is provided. The second joint portion  55   c  is formed in a triangular prism shape elongated along a rotation axis of the driving member  55 . 
     Meanwhile, a frame  59  at the apparatus main body  2  side is provided with a motor (not shown) as a driving means, and is provided with a main body side driving member  60  which is rotatable and transmits a driving force of the motor. At one end portion of the main body side driving member  60 , a hole portion  61  which is elongated along the rotation axis of the main body side driving member  60  is formed. Further, when the second joint portion  55   c  is internally fitted to the hole portion  61 , the main body side driving member  60  and the driving member  55  rotate integrally. Hence, the main body side driving member  60 , the driving member  55  and the screw portion  50  are integrally driven to rotate by the driving force of the motor. 
     As shown in  FIGS. 6 and 9 , the conveying blade  52  is spirally elongated in the axial direction of the screw shaft  51 . The conveying blade  52  includes a first blade  52   a  and a second blade  52   b  whose conveyance surface for conveying a toner has a different inclination from each other. As shown in  FIG. 5 , the first blade  52   a  is provided closer to a bearing  54  side than the toner supplying portion  32 , and the second blade  52   b  is provided closer to a driving member  55  side than the toner supplying portion  32 . Thus, when the screw shaft  51  is rotated, the toner at the bearing  54  side is conveyed to the toner supplying portion  32  by the first blade  52   a , and the toner at the driving member  55  side is conveyed to the toner supplying portion  32  by the second blade  52   b.    
     Further, as shown in  FIGS. 7 and 8 , each portion of the conveying blade  52  is respectively provided around the bearing  54  and the first joint portion  55   a  as the supporting portions  53 . 
     That is, as shown in  FIGS. 9 and 10 , a portion of the first blade  52   a  is formed so as to surround the end portion of the screw shaft  51  supported by the bearing  54 . At the end portion of this screw shaft  51 , a gap G is formed between an outer circumference face of the end portion of the screw shaft  51  and the portion of the first blade  52   a  to allow insertion of a circumferential wall of the bearing  54 . Thus, the portion of the first blade  52   a  is rotated along the outer circumference face of the bearing  54 . 
     Further, as shown in  FIGS. 8 and 9 , a portion of the second blade  52   b  is formed on the outer circumference face of the cylinder portion  51   a  which is externally fitted to the first joint portion  55   a . Thus, the portion of the second blade  52   b  is rotated integrally with the cylinder portion  51   a.    
     According to the above-mentioned configuration, in the toner container  21 , the screw shaft  51  is rotated in a state where the end portions of the screw shaft  51  are supported by the bearing  54  and the first joint portion  55   a  of the driving member  55  as the supporting portions  53  at the inside of the case body  31 . Further, the first blade  52   a  and the second blade  52   b  of the conveying blade  52  are rotated with the screw shaft  51 , so that the toner in the case body  31  is conveyed to the toner supplying portion  32 . The toner having conveyed to the toner supplying portion  32  is supplied to the apparatus main body  2  of the laser printer  1 . 
     Further, according to the present embodiment, the screw portion  50  can efficiently convey the toner in the case body  31  while the supporting parts  53  to support the screw shaft  51  are arranged closer to the inside than the side walls  31   a  and  31   b  of the case body  31 . 
     That is, the bearing  54  as the supporting portion  53  is arranged closer to the inside of the case body  31  than the side wall  31   a  of the case body  31 , so that it is possible to increase the flexibility of design of the outside face of the side wall  31   a  of the case body  31 . Consequently, it is possible to form the grip portion  44  in the side wall  31   a  of the case body  31  by a suitable layout. Further, the first joint portion  55   a  as the supporting portion  53  is arranged closer to the inside of the case body  31  than the side wall  31   b  of the case body  31 , so that it is possible to prevent the first joint portion  55   a  from significantly limiting a layout of the parts of the apparatus main body  2  side, such as the main body side driving member  60 . 
     Moreover, the first blade  52   a  which is rotated with the screw shaft  51  can convey the toner gathered around the bearing  54 , to the toner supplying portion  32 . Further, the second blade  52   b  which is rotated with the screw shaft  51  can convey the toner gathered around the cylinder portion  51   a , to the toner supplying portion  32 . Consequently, it is possible to efficiently convey the toner in the case body  31  to the toner supplying portion  32  and, consequently, suitably prevent the toner from aggregated around the supporting portions  53  which support the screw shaft  51 . 
     Further, the toner container  21  includes the cylindrical bearing  54  as the supporting portion  53 . Consequently, the inner circumference face of the bearing  54  can rotatably support the screw shaft  51 , and the first blade  52   a  of the conveying blade  52  can convey the toner gathered around the outer circumference face of the bearing  54 , to the toner supplying portion  32 . 
     Further, the toner container  21  includes the first joint portion  55   a  of the driving member  55  as the supporting portion  53  and the driving member  55  transmits a driving force to the screw shaft  51 . Consequently, the driving member  55  can drive and rotate the screw shaft  51 , and the second blade  52   b  of the conveying blade  52  can convey a toner gathered around the first joint portion  55   a  of the driving member  55 , to the toner supplying portion  32 . 
     Further, at the end portion of the screw shaft  51 , the cylinder portion  51   a  which is externally fitted to the first joint portion  55   a  of the driving member  55  is formed, and the portion of the second blade  52   b  of the conveying blade  52  is formed at the outer circumference face of the cylinder portion  51   a . Consequently, the portion of the second blade  52   b  of the conveying blade  52  can convey a toner gathered around the outer circumference face of the cylinder portion  51   a , to the toner supplying portion  32 . 
     Further, the laser printer  1  includes the toner container  21 . According to this configuration, the supporting portions  53  are arranged closer to the inside of the case body  31  than the side walls  31   a  and  31   b  of the case body  31 , so that it is possible to increase the flexibility of design of the outer faces of the side walls  31   a  and  31   b  of the case body  31 . Consequently, it is possible to easily form the grip portion  44  which the user grips to attach the toner container  21  to or detach the toner container  21  from the apparatus main body  2 , on the outside faces of the side walls  31   a  and  31   b  of the case body  31 . Moreover, it is possible to prevent a toner from being aggregated around the supporting portions  53 , and efficiently use the toner in the case body  31  so as to form an image. 
     Incidentally, in the above-mentioned embodiment, an example where portions of the conveying blade  52  are provided around the supporting portions  53  at the both ends of the screw portion  50  has been described. However, the present invention is not limited to this, and a portion of the conveying blade  52  may be provided around at least one of the supporting portions  53 . 
     Further, in the present embodiment, the laser printer  1  has been described as an example of the image forming apparatus. However, the image forming apparatus according to the present invention is not limited to this, and may be another image forming apparatus, such as copying machine, scanner or multifunction peripheral. 
     INDUSTRIAL APPLICABILITY 
     As described above, the present invention is useful for a toner case and an image forming apparatus including the same.