Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 U.S.C. 119 from Japanese Patent Application No. 2007-323472, which is filed on Dec. 24, 2007. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to developing apparatuses used in image forming apparatuses such as electrophotographic copying machines and printers in which a latent image on an image carrier is made visible, and to process cartridges and image forming apparatuses. 
     2. Related Art 
     In recent years a large number of models of recording apparatuses in which an electrophotographic principle is applied have been available in the market using a cartridge (a so-called process cartridge) aiming to improve operability and also to integrate into a single entity the members that execute the electrophotographic processes. 
     Furthermore, there is also a demand for recording apparatuses to be more compact such that greater compactness is desired also for the structural elements constituting the process cartridge. One of these structural elements is the developing apparatus. In the developing apparatus, a developer accommodating unit is formed in which developer is filled in advance, and the developer inside the developer accommodating unit is transported to a developer carrier via an opening. 
     On the other hand, there are technologies for sealing the opening using a seal member so as to prevent the developer inside the developer accommodating unit from leaking outside when transporting an unused process cartridge. The seal member is peeled off by a user at the commencement of usage. 
     SUMMARY 
     In an aspect of the present invention, there is provided a developing apparatus, comprising: a housing having an opening that opens towards an image carrier on which an electrostatic latent image is formed, and a developer storing unit in which a developer is stored; a developer carrier that carries the developer stored in the developer storing unit and transports the developer to a developing region in opposition to the image carrier; a partitioning frame arranged in a groove formed between the developer carrier and the developer storing unit of the housing, that is provided with a connecting hole which enables connect between the developer storing unit and the opening; a partition arranged on a side surface of the partitioning frame; and a closely contact section that causes the partitioning frame to closely contact to the groove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is an overall configuration diagram showing an image forming apparatus according to an exemplary embodiment of the present invention; 
         FIG. 2  is a perspective view showing a developing apparatus according to an exemplary embodiment; 
         FIG. 3  is an exploded perspective view showing principal components of a developing apparatus according to an exemplary embodiment; 
         FIG. 4  is a partial cross-sectional view as seen from a direction of arrows IV and IV shown in  FIG. 2 ; 
         FIG. 5  is a perspective view showing a partitioning frame and a peel-off seal; 
         FIG. 6  is a cross-sectional view showing an enlargement of an “a” portion of  FIG. 4 ; 
         FIG. 7  is a partial cross-sectional view as seen from a direction of arrows VII and VII shown in  FIG. 6 ; 
         FIG. 8  is a cross-sectional view from a same position as  FIG. 6  according to a modified example; and 
         FIG. 9  is a partial cross-sectional view as seen from a direction of arrows IX and IX shown in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary embodiment of the present invention is described with reference to the accompanying drawings. 
     Configuration 
     Overall Configuration of Image Forming Apparatus 
       FIG. 1  is a diagram showing an overall configuration of an image forming apparatus in which developing apparatuses according to an aspect of the invention are installed. 
     An image forming apparatus  1  according to the present exemplary embodiment is a so-called tandem-type color image forming apparatus in which image forming units  11  (specifically  11 Y,  11 M,  11 C, and  11 B) of four colors (in the present exemplary embodiment these are yellow, magenta, cyan, and black) are arranged in a vertical direction inside an apparatus casing  2 , and provided thereunder is a paper supply cassette  51 , in which papers  50  are accommodated for supply, and a paper transport path  52 , which is a transport path for the papers  50  from the paper supply cassette  51 , is arranged in a vertical direction along locations corresponding to each of the image forming units  11 . 
     The image forming units  11  form toner images for yellow, magenta, cyan, and black in order from the upstream side of the paper transport path  52  and are provided with process cartridges  12 , in which various process units are incorporated, and an exposure device  21  that irradiates a scanning light for image forming onto each of the process cartridges  12 . 
     Each of the process cartridges  12  is in a form of an integrated cartridge including a photosensitive drum  13 , a changing roller  14  that charges the photosensitive drum  13  in advance, a developing apparatus  30  that develops, with a corresponding color toner (in the present exemplary embodiment having a negative polarity for example), an electrostatic latent image that has been exposed and formed by the exposure device  21  on the photosensitive drum  13  that has been charged, and a cleaning device  15  that removes waste toner on the photosensitive drum  13 . 
     The exposure device  21  houses inside a case a semiconductor laser, a polygon mirror, an imaging lens, and a mirror, which are not shown in the diagram, and uses the polygon mirror to deflect and scan the light from the semiconductor laser such that a light image is guided to exposure points on the photosensitive drum  13  via the imaging lens and the mirror. 
     Further still, a transport belt  53  is arranged so as to rotate and move along the paper transport path  52  in locations corresponding to the photosensitive drums  13  of the image forming units  11 . The transport belt  53  is constructed using a belt material (rubber or resin) that is capable of achieving electrostatic adsorption of the papers  50  and is arranged spanning a pair of tensioning rollers  54  and  55 . 
     A paper adsorption roller  56  is arranged at an entrance site (a site opposing the tensioning roller  54 ) of the transport belt  53 , and the paper  50  is adsorbed to the transport belt  53  by applying a high-voltage adsorption voltage to the paper adsorption roller  56 . Furthermore, transfer rollers  57  are arranged respectively on a rear surface side of the transport belt  53  corresponding to the photosensitive drum  13  of each of the image forming units  11 , and the photosensitive drum  13  and the paper  50  on the transport belt  53  are caused to contact each other by the transfer roller  57 . And a predetermined transfer bias is applied as appropriate by a transfer bias power source between the transfer rollers  57  and the photosensitive drums  13 . 
     Furthermore, a pickup roller  61  that takes out the papers  50  with a predetermined timing is arranged near the paper supply cassette  51 , and this feeds in the papers  50  to transfer positions via transport rollers  62  and registration rollers  63 . 
     A fixing device  64  is provided on the paper transport path  52  positioned on a downstream side of the image forming unit  11 B, which is positioned the farthest downstream, and multiple discharge rollers  66  for discharging the papers are provided on the downstream side of the fixing device  64 , and discharged papers are collected in a collecting tray  67 , which is formed on an upper area of the apparatus casing  2 . 
     In the thus-configured image forming apparatus, image forming is carried out by the following processes. 
     In each of the image forming units  11  ( 11 Y,  11 M,  11 C, and  11 B), the photosensitive drum  13  is charged by the charging roller  14 , and after a latent image has been formed on the photosensitive drum  13  by the exposure device  21 , a visible image (toner image) is formed by the developing apparatus  30 . 
     Meanwhile, the paper  50  from the paper supply cassette  51  is drawn out by the pickup roller  61  with a predetermined timing, then fed into an adsorption position of the transport belt  53  via the transport rollers  62  and the registration rollers  63 , then fed into the transfer positions while adsorbed to the transport belt  53 . 
     The toner images on the photosensitive drum  13  of each of the image forming units  11  are successively transferred to the paper  50  by the transfer rollers  57 , then after the unfixed toner images of each of the color components on the paper  50  are fixed by the fixing device  64 , the now-fixed paper  50  is discharged to the collecting tray  67 . 
     Overview of Process Cartridge 
     Each of the process cartridges  12  is equipped with components such as the photosensitive drum  13 , the charging roller  14 , the developing apparatus  30 , and the cleaning device  15 . 
     Overview of Developing Apparatus 
       FIG. 2  to  FIG. 4  are diagrams showing the developing apparatus  30  according to the present exemplary embodiment.  FIG. 2  is a perspective view of the developing apparatus  30 ,  FIG. 3  is an exploded perspective view of principal components, and  FIG. 4  is a cross-sectional view as seen from a direction of arrows IV and IV shown in  FIG. 2 . 
     The developing apparatus  30  is equipped with a casing  31  having chambers divided into a developer accommodating unit  35  and a developing unit  36 , and an opening  31 A, an agitating auger  41  and a supply auger  42  arranged in the developer accommodating unit  35 , and a trimmer member  44 , and a paddle  45  arranged in the developing unit  36 . 
     A portion of the magnet roller  43  is arranged near the photosensitive drum  13  so as to be exposed from the opening  31 A of the casing  31 . The trimmer member  44  regulates the amount of developer held on the surface of the magnet roller  43 . The paddle  45  returns the developer released from the magnet roller  43  after developing is completed to the supply auger  42  side. Rotation from a same drive source is transmitted via gears to the agitating auger  41 , the supply auger  42 , the magnet roller  43 , and the paddle  45  such that each part is rotationally driven. 
     The casing  31  is constituted by a lower side housing  32 , an upper side housing  33 , and side covers  34  on the left and right. The inside of the casing  31  in which these parts  32  to  34  are assembled is divided into the developer accommodating unit  35  and the developing unit  36 . A developer G is filled inside the developer accommodating unit  35 . 
     In the casing  31 , grooves are formed at sites that constitute a boundary between the developer accommodating unit  35  and the developing unit  36  as shown in  FIG. 4 . These grooves are constituted by a lower groove  37  formed in lower side housing  32  and an upper groove  38  formed in the upper side housing  33 , while grooves formed in the side covers  34  are omitted from the diagrams. When the cartridge is unused, a partitioning frame  46  onto which a peel-off seal  47  has been stuck is inserted into the grooves. 
     It should be noted that the inside of the casing  31  is divided into the developer accommodating unit  35  and the developing unit  36  by this partitioning frame  46 . 
     As shown in  FIG. 6 , the shape of the lower groove  37  involves a groove width whose entrance is W 1  and whose interior is W 2 , with a groove depth whose deep portion is H 1  and whose shallow portion is H 2 , thus forming a stepped groove. Specifically, W 1  is 3.5 mm, W 2  is 1.5 mm, H 1  is 4 mm, and H 2  is 3.5 mm. 
     Description is given based on  FIG. 5  regarding the partitioning frame  46  and the peel-off seal  47 . 
     The partitioning frame  46  has a connecting hole  46 A, and a flange unit  46 B (see  FIG. 4 ) is formed on one of its long sides. Furthermore, the thickness of the part of the partitioning frame  46  that fits into the lower groove  37  is formed having a thickness substantially equivalent to the groove width W 2 . The casing  31  and the partitioning frame  46  are formed using an ABS resin (engineering plastic) for example. 
     An outer circumferential surface of the peel-off seal  47  is stuck to a surface of one side of the partitioning frame  46  using an adhesive so as to block the connecting hole  46 A. The length of the peel-off seal  47  is two times or more longer than the partitioning frame  46  so as to be stuck there traversing a lengthwise direction of the partitioning frame  46  twice. With the peel-off seal  47 , a front side in  FIG. 5  is a turn-back unit  47 A, and from a starting point until the turn-back unit  47 A is a first half that is adhered to the partitioning frame  46 , and from the turn-back unit  47 A until its free end is a second half, and this free end extends to the outside via a seal passing path (not shown in drawings) of the side cover  34 . 
     When peeling off the peel-off seal  47  from the partitioning frame  46 , the first half of the peel-off seal  47  is peeled off in order from its forward side from the partitioning frame  46  by pulling the free end that extends outside from the side cover in a direction of arrow A such that the turn-back unit  47 A moves successively rearward, and by peeling off the first half from the partitioning frame  46 , the peel-off seal  47  is completely peeled off such that the connecting hole  46 A is communicatively opened. 
     Features of Exemplary Embodiment 
     As shown in  FIG. 6  and  FIG. 7 , a feature of the developing apparatus  30  according to the present exemplary embodiment is that an elastic body  48  is provided having an adhesion layer (not shown in drawings) on one or both sides positioned on an other side surface of the partitioning frame  46  from the part of the partitioning frame  46  that is inserted into the lower groove  37 . For example, the elastic body  48  may be formed as a plate body using Real Sealer SP for toner seals (polyurethane foam made by Bridgestone Corporation) as a material. 
     As shown in  FIG. 7 , the elastic body  48  is provided in multiple locations at predetermined intervals, and while the partitioning frame  46  is inserted into the lower groove  37 , adhesion is improved between one side surface of the partitioning frame  46  and the lower groove  37  since a pushing force is applied to the partitioning frame  46  from the elastic body  48 . 
     Test Results 
     Results of testing are shown in which leakage of developer is measured for a developing apparatus  30  in which the elastic body  48  is provided in the lower groove  37  and a developing apparatus  30 ′ in which the elastic body  48  is not provided. 
     Focusing on the developer that leaks when a developing apparatus in a storage state is used, the inventors carried out testing in which amounts of the developer G adhering to the magnet roller  43  are measured after predetermined vibration is applied to the developing apparatus  30  in certain positions. 
     First, a position in which leakages could be considered to occur often is surmised as a case where the magnet roller  43  faced downward in a gravity direction, and in this position a test  1  is carried out in which three developing apparatuses  30 ′ are subjected for 20 minutes to random vibrations of frequencies from 5 Hz to 100 Hz and an amplitude of 3 cm, and as a result no remarkable leakage of developer is detected. 
     Converse to this, a test  2  is carried out in which vibrations are applied under the aforementioned conditions in a case where the magnet roller  43  faced upward in the gravity direction, and as a result, leakages as shown in Table 1 are detected. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Developing apparatus no. 
                 Adhesion amount (g) 
               
               
                   
                   
               
             
             
               
                   
                 1 
                 0.1 
               
               
                   
                 2 
                 0.5 
               
               
                   
                 3 
                 0.7 
               
               
                   
                   
               
             
          
         
       
     
     Further still, a test  3  is carried out in which vibrations are applied under the aforementioned conditions while the magnet roller  43  faced downward in the gravity direction after vibrations are applied under the aforementioned conditions while the magnet roller  43  faced upward in the gravity direction, and as a result, leakages as shown in Table 2 are detected. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Developing apparatus no. 
                 Adhesion amount (g) 
               
               
                   
                   
               
             
             
               
                   
                 1 
                 2.42 
               
               
                   
                 2 
                 1.50 
               
               
                   
                 3 
                 2.00 
               
               
                   
                   
               
             
          
         
       
     
     From these results, the following considerations are made. 
     Namely, it is considered that since gravity of the developer G inside the developer accommodating unit  35  is applied to the partitioning frame  46  while the magnet roller  43  faced downward in the gravity direction in test  1 , the partitioning frame  46  adhered to the groove with no leeway and as a result there is no leakage in this state. 
     On the other hand, since the gravity of the developer G did not act on the partitioning frame  46  such that there is leeway between the groove and the partitioning frame  46  while the magnet roller  43  faced upward in the gravity direction in test  2 , the developer G that swirled up inside the developer accommodating unit  35  escaped between the vibrating partitioning frame  46  and the groove, and it is considered that once the developer had escaped once a passageway is formed such that the developer G leaked out. 
     Further still, in the case of test  3  where vibration is applied while the magnet roller  43  faced upward in the gravity direction after which vibration is applied while the magnet roller  43  faced downward in the gravity direction, it is considered that the developer G leaked through the already formed passageway. 
     Next, results of carrying out testing identical to tests  2  and  3  are shown for the developing apparatus  30  according to the present exemplary embodiment. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Developing apparatus no. 
                 Adhesion amount (g) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 1 
                 0.02 
               
               
                   
                 2 
                 ≦0.0* 
               
               
                   
                 3 
                 0.04 
               
               
                   
                   
               
               
                   
                 *Leakage is beyond a limit of measurement, but visually confirmed. 
               
             
          
         
       
     
     
       
         
               
               
               
             
           
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 Developing apparatus no. 
                 Adhesion amount (g) 
               
               
                   
                   
               
             
             
               
                   
                 1 
                 0.05 
               
               
                   
                 2 
                 0.03 
               
               
                   
                 3 
                 0.03 
               
               
                   
                   
               
             
          
         
       
     
     As is clear from comparing the test results in tables 1 and 2 and tables 3 and 4, it is evident that occurrences of leakages of the developer G from the developer accommodating unit  35  are remarkably improved by providing the elastic body  48 . 
     Effects of Exemplary Embodiment 
     As described above, with the developing apparatus  30  according to the present exemplary embodiment, by providing the elastic body  48  having an adhesion layer (not shown in drawings) on one or both sides positioned on the other side surface of the partitioning frame  46  from the part of the partitioning frame  46  that is inserted into the lower groove  37 , the amount of developer G that leaks out from the developer accommodating unit  35  to the developing unit  36  side can be almost eliminated as is evident from the test results. As a result, in an operation of peeling off the peel-off seal  47  from the partitioning frame  46  when replacing the developing apparatus  30 , a user or service personnel and a surrounding area thereof can be reliably prevented from being smeared by developer. 
     Furthermore, of the front and back surfaces of the partitioning frame  46 , since the elastic body  48  is provided so as to be positioned on a surface side of the partitioning frame  46  where the peel-off seal  47  does not stick, the peel-off seal  47  is prevented from contacting or sandwiching the elastic body  48  and becoming an obstacle to the peel-off operation of the peel-off seal  47  when pealing off the peel-off seal  47  from the partitioning frame  46 , and therefore the peel-off seal  47  can be reliably prevented from becoming severed. 
     Further still, to improve the adhesion between the partitioning frame  46  and the lower groove  37 , an entire circumference thereof may be secured using an adhesive, but in this case costs are increased and the casing  31  cannot be reused. In contrast to this, with the developing apparatus  30  according to the present exemplary embodiment, the adhesion between the partitioning frame  46  and the lower groove  37  is improved by the elastic body  48 , such that cost reductions can be achieved and reuse of the casing  31  can also be achieved. 
     MODIFIED EXAMPLE 1 
     In the foregoing exemplary embodiment, description is given regarding a case where the elastic body  48  is provided to a closely contact section, but the present invention is not limited to this and this may be a protrusion  49  as shown in  FIG. 8  and  FIG. 9 . The protrusion  49  may be formed at the lower side housing  32  where the lower groove  37  is formed, or may be formed at the partitioning frame  46 , or may be formed at both of these members. 
     Furthermore, instead of the elastic body  48 , an adhesive may also be applied. In this case, it is necessary to determine the amount to be applied taking care so that it does not stick out from the lower groove  37 . Further still, the closely contact section may be a member that increases adhesion of the partitioning frame  46  to the lower groove  37  such as double-sided tape or a sponge and the like. 
     MODIFIED EXAMPLE 2 
     Further still, in the foregoing embodiment and modified example 1, multiple instances of the elastic body  48 , the protrusions  49 , and the adhesive are provided with the closely contact section at predetermined intervals on the lower groove  37 , but the present invention is not limited to this, and the closely contact section may be configured as a sheet-shaped member extending across the lower groove  37  lengthwise. 
     MODIFIED EXAMPLE 3 
     In the foregoing exemplary embodiment and modified examples 1 and 2, the closely contact section is provided between the lower groove  37  of the lower side housing  32  and the partitioning frame  46 , but naturally a closely contact section may also be provided in a groove of the upper side housing  33  or the side covers  34 . 
     MODIFIED EXAMPLE 4 
     In the foregoing exemplary embodiment, the peel-off seal  47  is used as a partition that blocked the connecting hole  46 A of the partitioning frame  46 , but the present invention is not limited to this, and a slidable partitioning panel may be used in the partitioning frame  46  as the partition. 
     Furthermore, the closely contact section is provided positioned on a surface side of the front and back sides of the partitioning frame  46  where the peel-off seal  47  is not adhered, but this may be provided positioned on a surface of the front and back sides of the partitioning frame  46  where the peel-off seal  47  is adhered. 
     The foregoing description of the embodiments of the present invention is provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments are chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

Technology Category: 3