Abstract:
A developing apparatus includes: a housing having an opening that opens towards an image carrier onto which an electrostatic latent image is formed, a developer accommodating unit in which a developer is accommodated, and a connecting hole connecting with the developer accommodating unit; a developer carrier that carries the developer accommodated in the developer accommodating unit and transports the developer to a developing region in opposition to the image carrier; a sheet member that is provided in the developer accommodating unit and seals the continuous hole; and an insertion hole that is formed in the housing and allows the sheet member to be inserted through when the sheet member is pulled out, wherein the insertion hole has a shape having ends which are more distant from the connecting hole than parts of the shape other than the ends.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority under 35 USC 119 from a Japanese patent application No. 2008-73805 filed on Mar. 21, 2008. 
       BACKGROUND  
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a developing apparatus, a process cartridge, an image forming device, and a developer cartridge which are used in an image forming device such as an electronic copying machine or a printer to visualize a latent image on an image carrier. 
         [0004]    2. Related Art 
         [0005]    In recent years, a large number of recording devices have been available on the market as recording devices to which principles of electrophotography are applied. The recording devices of this type use a cartridge (a so-called process cartridge) which integrates plural members for executing an electrophotographic process. These recording devices have improved operability. 
         [0006]    Since there has been a demand for downsizing of recording devices, members forming a part of such a process cartridge have also been downsized. One of these members is a developing apparatus. In the developing apparatus, a developer accommodating unit is formed and is filled with a developer in advance. The developer in the developer accommodating unit is conveyed outside through a continuous hole. 
       SUMMARY  
       [0007]    The present invention provides a developing apparatus, a process cartridge, an image forming device, and a developer cartridge which are capable of preventing a sheet member from being torn off when the sheet member is pulled out and inserted into a continuous hole. 
         [0008]    According to one aspect of the invention, there is provided a developing apparatus including: a housing having an opening that opens towards an image carrier onto which an electrostatic latent image is formed, a developer accommodating unit in which a developer is accommodated, and a connecting hole connecting with the developer accommodating unit; a developer carrier that carries the developer accommodated in the developer accommodating unit and transports the developer to a developing region in opposition to the image carrier; a sheet member that is provided in the developer accommodating unit and seals the continuous hole; and an insertion hole that is formed in the housing and allows the sheet member to be inserted through when the sheet member is pulled out, wherein the insertion hole has a shape having ends which are more distant from the connecting hole than parts of the shape other than the ends. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]    Exemplary embodiment of the present invention will be described in detail based on the following figures, wherein: 
           [0010]      FIG. 1  is a view showing an overall structure of an image forming device according to an exemplary embodiment of the invention; 
           [0011]      FIG. 2  is a perspective view showing a developing apparatus according to the exemplary embodiment; 
           [0012]      FIG. 3  is an exploded perspective view showing a main part of the developing apparatus according to the exemplary embodiment; 
           [0013]      FIG. 4  is a partial cross-sectional view cut along arrows IV in  FIG. 2 ; 
           [0014]      FIG. 5  is a perspective view showing a partition frame and a seal member; 
           [0015]      FIG. 6  is a partial cross-sectional view cut along arrows VI in  FIG. 4 ; 
           [0016]      FIG. 7  shows a state before forming a sheet insertion hole; 
           [0017]      FIG. 8  is a view showing a state in which a sheet member is inserted into the sheet insertion hole; 
           [0018]      FIG. 9  is a plan view showing a seal member according to the exemplary embodiment; 
           [0019]      FIGS. 10A ,  10 B, and  10 C are cross-sectional views respectively cut along arrows a, b, and c in  FIG. 9 ; 
           [0020]      FIG. 11  shows Modification 2; 
           [0021]      FIG. 12  shows a state before forming a sheet insertion hole in Modification 3; 
           [0022]      FIG. 13  shows a state in which a sheet member is inserted in a sheet insertion hole in Modification 3; 
           [0023]      FIG. 14  is a plan view of the seal member in Modification 3; and 
           [0024]      FIGS. 15  are cross-sectional views respectively cut along arrows a, b, and c in  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION  
     1. Exemplary Embodiments 
     1-1. Overall Structure of Image Forming Device 
       [0025]      FIG. 1  shows an overall structure of an image forming device onto which is mounted a developing apparatus according to the invention. 
         [0026]    The image forming device  1  according to the exemplary embodiment is a so-called tandem type color image forming device in which image forming units  11  (e.g.,  11 Y,  11 M,  11 C, and  11 B) for four colors are arranged vertically in a device housing  2 . Below the image forming units  11 , a sheet feed cassette  61  is provided, and a sheet convey path  62  for paper sheets P from the sheet feed cassette  61  is provided extending vertically through positions corresponding to the image forming units  11 . 
         [0027]    The image forming units  11  for respectively forming yellow, magenta, cyan, and black toner images are arranged vertically in an order from the upstream side of the paper convey path  62 . Each of the image forming units  11  has a process cartridge  12  and an exposing device  21 . Various process units are further incorporated into the process cartridge  12 , and the exposing device  21  illuminates the process cartridge  12  with scanning light for image formation. 
         [0028]    Each process cartridge  12  integrally holds a photosensitive drum  13 , a charge roll  14 , a developing apparatus  30 , and a cleaning device  15 . The charge roll  14  electrically charges the photosensitive drum  13  in advance. The developing apparatus  30  develops an electrostatic latent image with a corresponding color toner (for example, polarized negatively in this embodiment), wherein the electrostatic latent image is exposed and formed on the charged photosensitive drum  13 . The cleaning device  15  removes a wasteful toner on the photosensitive drum  13 . 
         [0029]    The exposing device  21  has a case which contains a semiconductor laser not shown, a polygon mirror, an imaging lens, and a mirror. Light from the semiconductor laser is deflected for scanning the photosensitive drum  13  by the polygon mirror so that a light image is guided to an exposing point on the photosensitive drum  13 . 
         [0030]    Further, a conveyor belt  63  which circulates along the sheet convey path  62  is provided through positions of the image forming units  11  respectively corresponding to the photosensitive drums  13 . The conveyor belt  63  is made of a belt material (rubber or resin) which can electrostatically suction a paper sheet P, and be wound around a pair of tension rolls  64  and  65 . 
         [0031]    At an inlet portion (facing a tension roll  64 ) of the conveyor belt  63 , there is provided a paper sheet suction roll  66 . A high suction voltage is applied to the sheet suction roll  66 , thereby to suction a paper sheet P onto the conveyor belt  63 . Further, a transfer roll  67  is provided on the rear side of the conveyor belt  63  corresponding to the photosensitive drum  13  of each of the image forming units  11 . The photosensitive drums  13  are respectively put in tight contact with the transfer rolls  67 . Further, a predetermined transfer bias is appropriately applied between the transfer roll  67  and the photosensitive drum  13  by a transfer bias power supply. 
         [0032]    Near the sheet feed cassette  61 , there is provided a pickup roll  71  which rolls out a paper sheet P at a predetermined timing to transfer positions by conveyor rolls  72  and registration rolls  73 . 
         [0033]    A fixing device  74  is provided on the sheet convey path  62  and positioned in a further downstream side of the image forming unit  11 B which is provided in the most downstream side among the image forming units  11 . In the more downstream side of the fixing device  74 , there are provided plural sheet output rolls  76  to output paper sheets. Paper sheets which are output are put on a container tray  77  formed above a device housing  2 . 
         [0034]    In the image forming device configured as described above, images are formed through a process as follows. 
         [0035]    In each of the image forming units  11  ( 11 Y,  11 M,  11 C, and  11 B), the photosensitive drum  13  is electrically charged by the electric charge roll  14 , and a latent image is formed on the photosensitive drum  13  by the exposing device  21 . Thereafter, a visible image (toner image) is formed by the developing apparatus  30 . 
         [0036]    Meanwhile, a paper sheet P is output from the sheet feed cassette  61  at a predetermined timing by the pickup roll  71  and fed to a suction position on the conveyor belt  63  through the conveyor rolls  72  and registration rolls  73 . The paper sheet P is then fed to transfer positions, kept suctioned to the conveyor belt  63 . 
         [0037]    Toner images on the photosensitive drums  13  in the image forming units  11  are transferred sequentially to the paper sheet P. Unfixed toner images of individual color components on the paper sheet P are fixed to the fixing device  74  by the fixing device  74 . The paper sheet P subjected to a fixing process is then output onto the container tray  77 . 
       1-2. Outline of Process Cartridge 
       [0038]    The process cartridge  12  has a photosensitive drum  13 , an electric charge roll  14 , a developing apparatus  30 , a cleaning device  15 , etc. 
       1-3. Outline of Developing Apparatus 
       [0039]      FIGS. 2 to 4  show the developing apparatus  30  according to this exemplary embodiment.  FIG. 2  is a perspective view of the developing apparatus  30 .  FIG. 3  is an exploded perspective view of a main part of the developing apparatus  30 .  FIG. 4  is a cross-sectional view cut along arrows IV in  FIG. 2 . In the description made below, lateral and lengthwise directions of the developing apparatus are respectively defined as X and Y axes. 
         [0040]    The developing apparatus  30  has: a housing  31  including an opening  31 A and a chamber which is partitioned into a developer accommodating unit  35  and a developing part  36 ; an agitation auger  41  and a supply auger  42  which are provided in the developer accommodating unit  35 ; and a magnetic roll  43 , a trimmer member  44 , and a paddle  45  which are provided in the developing part  36 . 
         [0041]    A part of the magnetic roll  43  is exposed to the outside through the opening  31 A and is positioned close to the photosensitive drum  13 . The trimmer member  44  regulates an amount of developer which is carried by the surface of the magnetic roll  43 . After completion of development, a remaining developer is released from the magnetic roll  43  and is returned to the side of the supply auger  42 . Further, torque from one identical drive source is transmitted through gears to the agitation auger  41 , supply auger  42 , and paddle  45 , which are driven to rotate accordingly. 
         [0042]    The housing  31  is constituted of a lower housing  32 , an upper housing  33 , and left and right side covers  34 . The housing  31  which is formed by assembling the parts  32  to  34  is partitioned into the developer accommodating unit  35  and the developing part  36  by a partition frame  46 . A developer G is filled into the developer accommodating unit  35 . 
         [0043]    In the housing  31 , grooves are formed at a boundary between the developer accommodating unit  35  and the developing part  36 , as shown in  FIG. 4 . The grooves are a lower groove  37  formed in the lower housing  32  and an upper groove  38  formed in the upper housing  33 . Parts of the grooves which extend out and formed in the side covers  34  are omitted from the figures. The partition frame  46  to which a seal member is bonded is engaged in these grooves during an unused state. 
         [0044]    A developer receiver part  50  which will be described later is formed at one end in the lengthwise direction of the upper housing  33 . 
         [0045]    The partition frame  46  and a seal member  48 .will now be described based on  FIG. 5 . 
         [0046]      FIG. 5  shows a relationship between the partition frame  46  and the seal member  48 . The partition frame  46  includes a continuous feed hole  47  through which the developer accommodating unit  35  and the developing part  36  communicate with each other. The seal member  48  has an outer periphery which is bonded to a side surface of the partition frame  46 , so as to seal the continuous feed hole  47 . The seal member  48  is substantially longer by twice or more than the continuous feed hole  47  in lengthwise (Y axis) directions of the partition frame  46  since the seal member  48  extends toward an end in one lengthwise direction of the partition frame  46  and is further folded back so as to extend in the other lengthwise direction. The left end of the seal member  48  in  FIG. 5  is a folding part  48 A. A part of the seal member  48 , which extends from a base end to the folding part  48 A, is referred to as a fore part. The other part, which extends from the folding part  48 A to a free end of the seal member  48 , is a returning part. The free end is drawn to the outside through a seal insertion hole (not shown) formed between the upper housing  33  and the lower housing  32  and through a seal path (not shown) in a side cover  34 . 
         [0047]    When separating the seal member  48  from the partition frame  46 , the free end drawn out of one side cover  34  is pulled in a direction of an arrow A. The fore part of the seal member  48  is thereby gradually peeled off from the front side in the figure, and accordingly, the folded part  48 A shifts gradually toward the deep side in the figure. Finally, the seal member  48  is completely peeled off, and the continuous feed hole  47  is opened thereby making the developer accommodating unit  35  and the developing part  36  communicate with each other. 
         [0048]    Next, the developer receiver part  50  will be described with reference to  FIGS. 4 ,  6 , and  7 .  FIG. 6  is a cross-sectional view cut along arrows VI in  FIG. 4 .  FIG. 7  is a side view of the part shown in  FIG. 6 . 
         [0049]    The developer receiver part  50  has an outer part  50 A, a cap part  50 C, and a press spring  50 E. The outer part  50 A is formed in a semi-cylindrical shape on the upper housing  33 , and has a long regulation hole  50 B which is cut in the outer part  50 A so as to extend in a lengthwise direction (X axis direction) of the outer part  50 A. The cap part  50 C slides inside the outer part  50 A and a protrusion  50 D is formed on the outer part  50 A. The press spring  50 E presses the cap part  50 C in a direction of shutting the cap part  50 C. A continuous charge hole  51  is cut in the housing  33  at a position where the developer receiver part  50  is formed. 
         [0050]    Next, a relationship between the developer receiver part  50  and the seal member  48  will be described. The seal member  52  has an outer periphery which is bonded to an inner side surface of the upper housing  33 , so as to seal the continuous charge hole  51 . A left end of the seal member  52  in  FIG. 6  is a folding part  52 A of the seal member  52 . A part of the seal member  52 , which extends from a base end to the folding part  52 A, is referred to as a fore part which is bonded to the periphery of the continuous charge hole  51 . The other part of the seal member  52 , which extends from the folding part  52 A to a free end of the seal member  52 , is a returning part. The free end is extended outside through a seal insertion hole  53  formed between the upper housing  33  and the lower housing  32  and through a seal path (not shown) in a side cover  34 . 
       1-4. Features of Exemplary Embodiment 
       [0051]    A feature of the developing apparatus  30  according to this embodiment is that the seal insertion hole  53  formed between the upper housing  33  and the lower housing  32  is shaped like an arc. As a result, the ends of the seal insertion hole  53  are more distant from the continuous charge hole  51  than other parts of the seal insertion hole  53 . The seal insertion hole  53  is constituted of a concave hole end surface  53 A formed on the upper housing  33 , and a convex hole end surface  53 B formed on the lower housing  32 . The hole end surfaces  53 A and  53 B are coupled with each other thereby forming the arc-like seal insertion hole  53 . 
         [0052]    Each of ends of the hole end surface  53 B formed on the lower housing  32  is chamfered at an angle α. The angle α is set to 10°&lt;α&lt;70° (or more desirably 30°&lt;α&lt;60°). As a result, a seal material  54  provided on the hole end surface  53 B is firmly fixed. 
         [0053]    A seal member  54  made of an elastic material is provided for surfaces of the seal insertion hole  53  which are formed by the lower housing  32 . A leakage prevention seal member  55  made of an elastic material is provided for surfaces of the seal insertion hole  53  which are formed by the upper housing  33 . 
         [0054]    The seal member  54  is bonded to surfaces including the hole end surface  53 A of the lower housing  32 , and then, the upper housing  33  and the lower housing  32  are engaged with each other so that the seal member  52  is sandwiched between the hole end surfaces  53 A and  53 B. In this manner, the seal member  52  has an arc-like cross-section inside the seal insertion hole  53 , as shown in  FIG. 8 . 
         [0055]    Next, the shape of the seal member  52  inserted into the seal insertion hole  53  will be described with reference to  FIGS. 9 and 10 .  FIG. 9  is a top view of the seal member  48 .  FIGS. 10A ,  10 B, and  10 C are cross-sectional views respectively cut along arrows a, b, and c. In  FIG. 9  and  FIG. 10 , an arc-like shape is exemplarily drawn with a smaller radius than an actual radius for the purpose of clearly emphasizing the shape of the seal member  52 . 
         [0056]    A part of the seal member  52  covering the continuous charge hole  51  is substantially flat since the periphery of this part of the seal member  52  is fixed to the periphery of the continuous charge hole  51 . Another part of the seal member  52  which is inserted into the seal insertion hole  53  is shaped like an arc. That is, the returning part  52 C of the seal member  52  is substantially flat at a position (e.g., within an area corresponding to the continuous charge hole  51 ) where the fore part  52 B up to the folding part  52 A overlaps the returning part  52 C. The shape of the seal member  52  becomes gradually arc-like from the position toward the seal insertion hole  53 . Therefore, between a position a to a position c, a center line  52   a  as a center in a widthwise direction (X axis direction) is defined on the seal member  52 . Slopes  52   b  are formed from the center line  52   a  as a boundary toward two ends in widthwise directions (X axis directions). Further toward the seal insertion hole  53 , inclinations of the slopes  52   b  become gradually sharper and closer to inclinations of the seal insertion hole  53  as shown in  FIGS. 10B and 10C . 
       1-5. Effects of Exemplary Embodiment 
       [0057]    As has been specifically described above, the shape of the seal insertion hole  53  is formed like an arc. Therefore, the shape of the seal member  52  which seals the continuous charge hole  51  in the developer receiver part  50  gradually changes form into an arc-like shape from the continuous charge hole  51  toward the seal insertion hole  53 . In this manner, a developer G which goes into the folding part  52 A or goes in-between the seal member  52  and the upper housing  33  is released by being guided along the slopes  52   b  formed on the seal member  52 . Accordingly, accumulation of the developer G near the seal insertion hole  53  can be steadily reduced so that the developer is prevented from accumulating thereby decreasing the resistance to pulling out of the seal member  52 . Further, the seal member  52  is prevented from being torn due to such resistance of an accumulative developer when the seal member  52  is peeled off. 
         [0058]    In addition, the slopes of the seal member  52  are formed so that inclinations of the slopes  52   b  become gradually steeper toward the seal insertion hole  53 . Accordingly, the developer G accumulates at a position where the seal member  52  has a nearly flat cross-section. Therefore, if the developer C is caught in by the seal member  52  as the seal member  52  is pulled out, the developer G moves together with the sheet member and is then released along the gradually increasing inclinations of the slopes  52   b.    
         [0059]    As described above, accumulation of the developer G near the seal member  52  is reduced by only a simple change in form of the seal insertion hole  53  into an arc-like shape. In this manner, resistance which is caused by accumulation of the developer G when a user pulls out the seal member  52  by drawing the free end  52 D of the seal member  52  is reduced so that the seal member  52  is steadily prevented from being torn. As a result, reliability of the developing apparatus  30  can be improved. 
         [0060]    Usually, the developing apparatus  30  is transported with the X and Y axes basically kept horizontal, as shown in  FIGS. 2 and 4 . Gravitational force therefore acts in the directions toward the ends of the slopes  52   b  from the center line  52   a  (folding curve  52   a ), on the slopes  52   b  where the seal member  52  is formed. Interaction between the gravitational force and formation of the seal member  52  (slopes  52   b ) reduces accumulation of a developer G near the seal member  52 . This interaction is particularly effective when the seal member  52  which is formed by the seal insertion hole  53  has a shape in which the ends are positioned at gravitationally lower positions than positions of the other parts of the shape. 
         [0061]    Further, the seal insertion hole  53  is provided with the seal member  52  and leakage prevention seal member  55  by which the seal member  52  is maintained pressed. The developer G filled in the developer accommodating unit  35  is prevented from leaking outside. 
       2. Modifications 
     2-1. Modification 1  
       [0062]    The exemplary embodiment exemplifies a case that the shape of the seal insertion hole  53  in which the seal member  52  is inserted is formed into an arc-like shape in order to change the shape of the seal member  52  which seals the continuous charge hole  51 . However, the invention is not limited to this case but the shape of the seal insertion hole  53  in which the seal member  48  for sealing the continuous feed hole  51  may alternatively be formed into an arc-like shape. 
       2-2. Modification 2 
       [0063]    Also in the exemplary embodiment, the hole end surfaces  53 A and  53 B are respectively formed on the upper housing  33  and the lower housing  32  in order to form the seal insertion hole  53  into an arc-like shape. However, only one hole end surface may be formed on one of the upper and lower housings. For example, as shown in  FIG. 11 , a hole end surface  53 B may be formed only on the lower housing  32 . In this case, the seal member  52  is pressed against the hole end surface  53 B by the leakage prevention seal material  55  provided on the upper housing  33 , and the shape of the seal member  52  is accordingly deformed into an arc-like shape. 
       2-3. Modification 3 
       [0064]    The shape of the seal insertion hole  53  is not limited to an arc-like shape but may alternatively be a substantially inverted V-shape. In this case, the shape of the seal member  52  is deformed as shown in  FIGS. 12 to 15 . 
         [0065]    The seal insertion hole  53  is constituted of a concave hole end surface  53 A formed on the upper housing  33  and a convex hole end surface  53 B formed on the lower housing  32 . The seal insertion hole  53  having a substantially inverted V-shape is formed by engaging the hole end surfaces  53 A and  53 B with each other. 
         [0066]    After bonding a seal material  54  to a surface of the lower housing  32  which includes the hole end surface  53 B, the upper housing  33  and the lower housing  32  are fitted to each other so as to sandwich a seal member  52  between the hole end surfaces  53 A and  53 B. As a result, the seal member  52  has a substantially inverted V-shaped cross-section inside the seal insertion hole  53 , as shown in  FIG. 13 . 
         [0067]    Next, the shape of the seal member  52  formed by the seal insertion hole  53  having also a substantially inverted V-shape will be described with reference to  FIGS. 14 and 15 . 
         [0068]      FIG. 14  is a top view of the seal member  52  according to Modification 3.  FIGS. 15A ,  15 B, and  15 C are respectively cross-sectional views cut along arrows a, b, and c. 
         [0069]    A part of the seal member  52  covering the continuous charge hole  51  is substantially flat since the periphery of this part of the seal member  52  is fixed to the periphery of the continuous charge hole  51 . Another part of the seal member  52  which is inserted into the seal insertion hole  53  has an arc-like cross-section. That is, the returning part  52 C of the seal member  52  is substantially flat at a position (e.g., within an area corresponding to the continuous charge hole  51 ) where the fore part  52 B up to the folding part  52 A overlaps the returning part  52 C. The shape of the seal member  52  becomes gradually arc-like toward the seal insertion hole  53 . Therefore, between a position a to a position c, a center line  52   a  as a center in widthwise directions (X axis directions) is defined on the seal member  52 . Slopes  52   b  are formed extending from the center line  52   a  as a boundary toward two ends in the widthwise direction (X axis direction). Further toward the seal insertion hole  53 , inclinations of the slopes  52   b  become gradually sharper and closer to inclinations of the seal insertion hole  53  as shown in  FIGS. 15B and 15C . 
         [0070]    In this manner, the same effects as obtained in the exemplary embodiment can be obtained by the seal member  52  which changes form by the seal insertion hole  53  having a substantially inverted V-shape. 
         [0071]    The shape of the seal insertion hole  53  is not limited to a substantially inverted V-shape and an arc-like shape but needs only to satisfy a condition that ends of the seal insertion hole  53  are more distant from the continuous hole than other parts of the seal insertion hole  53 . In other words, the seal member  52  needs only to have the slopes  52   b.    
         [0072]    Further, a hole end surface may be formed on only one of the upper housing  33  and the lower housing  32 , as in Modification 2. 
       2-4. Modification 4 
       [0073]    The exemplary embodiment as described above is configured so that the shape of the seal member in the developing apparatus  30  is deformed. However, the invention is not limited to this configuration but has a developer accommodating unit such as a toner cartridge but may be applied to a developer cartridge (or developer container) having a developer accommodating unit in which a seal member for sealing a continuous hole is employed. 
         [0074]    The foregoing description of the exemplary embodiment of the present invention has been provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiment were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to he particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.