Abstract:
A wet-type image forming apparatus includes a body having an openable door. A developing unit is installed in the body and develops an image on a photosensitive body. An ink cartridge is detachable with respect to the body and stores ink therein. A fitting unit is installed between the developing unit and the ink cartridge. The fitting unit moves up and down to couple the developing unit to the ink cartridge to withdraw the ink from the developing unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 2004-641 f2 filed Aug. 14, 2004, in the Korean Intellectual Property Office, the entire disclosure of which is hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a wet-type image forming apparatus using a liquid developer. More particularly, the present invention relates to a wet-type electrophotographic image forming apparatus including an ink cartridge for feeding ink to or withdrawing ink from a developing unit and a fitting unit.  
         [0004]     2. Description of the Related Art  
         [0005]     Generally, image forming apparatuses can be classified into dry-type image forming apparatuses using a powdered dry developer and wet-type image forming apparatuses using a liquid wet developer. The dry-type and wet-type image forming apparatuses each provide certain advantages. However, the wet-type image forming apparatuses can obtain a clearer, higher resolution printed material than the dry-type image forming apparatuses. Particularly, with the increasing popularization of digital cameras, a clear, high-quality printed material having natural color is required. Thus, the demand for color image forming apparatuses has been gradually increased.  
         [0006]     However, in such a wet-type image forming apparatus, a much larger amount of developer than an amount of developer necessary for substantial printing should be fed to a developing unit performing a developing process to obtain satisfactory printing quality. Thus, developer that is not being used in printing is withdrawn to an ink cartridge.  
         [0007]      FIG. 1  is a schematic view of a conventional wet-type electrophotographic image forming apparatus performing such an ink withdrawing process. As shown in  FIG. 1 , the wet-type electrophotographic image forming apparatus includes developing units  16  including photosensitive bodies  12 , ink cartridges  15  feeding ink to the developing units  16  and withdrawing the ink from the developing units  16 , and fitting units  20  coupling the developing units  16  and the ink cartridges  15 .  
         [0008]     A reference numeral  18  denotes an intermediate transfer belt to which images formed on the photosensitive bodies  12  are transferred to be overlapped. Reference numeral  17  denotes transfer backup rollers transferring the images from the photosensitive bodies  12  to the intermediate transfer belt  18 . A reference character P denotes a paper transferring path.  
         [0009]     The fitting units  20  include coupling tubes  25  forming flowing paths for the ink, nut and bolt fitting portions  21  and  22  coupling the developing units  16  and the coupling tubes  25 , nut and bolt fitting portions  23  and  24  coupling the ink cartridges  15  and the coupling tubes  25 , and withdrawing pumps  26 .  
         [0010]     A process of circulating the ink in the wet-type electrophotographic image forming apparatus having the above-described structure will now be described. After the ink cartridges  15  and the developing units  16  are mounted in the wet-type electrophotographic image forming apparatus, the nut and bolt fitting portions  21 ,  22 ,  23 , and  24  are combined between the ink cartridges  15  and the fitting units  20  and between the developing units  16  and the fitting units  20 . Thereafter, when a printing command is requested, the ink is fed from the ink cartridges  15  to the developing units  16  through feeding pumps (not shown). After a predetermined developing process is performed, the ink may not be used for a printing operation and remains in the developing units  16 . The remaining ink is withdrawn to the ink cartridges  15  through the withdrawing pumps  26  and the coupling tubes  25 .  
         [0011]     Coupling apparatuses are necessarily required between the developing units  16  and the ink cartridges  15  to circulate wet ink. Also, the airtightness of the coupling apparatuses is very important in terms of the characteristics of the wet ink. In the above-described coupling and airtightness methods, the coupling apparatuses, such as the bolt fitting portions  22  and  24  and the nut fitting portions  21  and  23  including O-rings and springs, are generally used with the developing units  16  and the ink cartridges  15 .  
         [0012]     However, the above-mentioned coupling apparatuses include additional power sources such as pumps and nut and bolt fitting portions. Thus, the structure of the coupling apparatuses is complicated and manufacturing costs for the coupling apparatuses is increased. Moreover, the nut and bolt fitting portion  23  and  24  should be manually combined to connect the fitting units  20  and the ink cartridges  15 .  
         [0013]     Furthermore, during the ink withdrawing process, the flowing paths for the ink between the fitting units  20  and the ink cartridges  15  may be curved, and the area of the flowing paths may be suddenly reduced. Thus, the ink may stick to the flowing paths. As a result, the flowing paths may be clogged or a function of combining or opening and closing the fitting units  20  may be deteriorated. Particularly, this may frequently occur in places where the nut fitting portions  21  and  22  and the bolt fitting portions  23  and  24  are combined or in places where the bolt fitting portions  22  and  24  are coupled to the coupling tubes  25 . When the nut and bolt fitting portions  21 ,  22 ,  23 , and  24  or the coupling tubes  25  are clogged, the ink may be continuously fed to the developing units  16  but not withdrawn from the developing units  16 . Thus, the ink may overflow in the developing units  16 . The overflowing ink may contaminate various components of the wet-type electrophotographic image forming apparatus. As a result, the wet-type electrophotographic image forming apparatus may not operate. Also, the ink may flow outside the wet-type electrophotographic image forming apparatus. Thus, the surroundings may be seriously contaminated.  
         [0014]     Accordingly, a need exists for an improved wet-type electrographic image forming apparatus in which withdrawn ink does not clog a drainpipe or contaminate surrounding apparatus.  
       SUMMARY OF THE INVENTION  
       [0015]     Accordingly, an aspect of the present invention is to provide a wet-type electrophotographic image forming apparatus including a simply structured fitting unit capable of not changing a path of ink flow during an ink withdrawing process.  
         [0016]     According to another aspect of the present invention, a wet-type electrophotographic image forming apparatus including a body having an openable door, a developing unit installed in the body and developing an image on a photosensitive body, an ink cartridge detachable with respect to the body and that stores ink therein, and a fitting unit installed between the developing unit and the ink cartridge. The fitting unit moves up and down to couple the developing unit to the ink cartridge to withdraw the ink from the developing unit.  
         [0017]     The fitting unit may move in association with opening and closing of the door. Therefore, the fitting unit descends to thereby fluidly connect the developing unit and the ink cartridge. When the door is opened, the fitting unit ascends to thereby separate the developing unit from the ink cartridge.  
         [0018]     The fitting unit may include a drainpipe that forms an ink flowing path and that ascends and descends in a substantially vertical direction to couple the developing unit to and separate the developing unit from the ink cartridge. A drainpipe transferring unit moves in association with the door so as to move the drainpipe.  
         [0019]     The drainpipe transferring unit may include a coupling member that moves substantially horizontally, and a wire that substantially vertically moves the drainpipe with the horizontal movement of the coupling member. The drainpipe transferring unit may further include a flexible film having a first end fixed to the drainpipe and a second end fixed to the holder to substantially prevent the ink inside the developing unit from flowing out from the drainpipe and into the drainpipe transferring unit.  
         [0020]     The ink cartridge may include a drainpipe inlet into which the drainpipe is inserted. A transferring bar moves with the opening and closing of the door to horizontally move the coupling member.  
         [0021]     Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]     The above aspects and features of the present invention will be more apparent by describing certain embodiments of the present invention with reference to the accompanying drawings, in which:  
         [0023]      FIG. 1  is a schematic view of a conventional wet-type electrophotographic image forming apparatus;  
         [0024]      FIG. 2  is a schematic view of a wet-type electrophotographic image forming apparatus according to an embodiment of the present invention;  
         [0025]      FIG. 3  is a perspective view of an ink cartridge of  FIG. 2 ;  
         [0026]      FIG. 4  is an enlarged elevational view of the main components of the ink cartridge of  FIG. 2 ; and  
         [0027]      FIG. 5  is an enlarged elevational view of  FIG. 4  in which a door is closed. 
     
    
       [0028]     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.  
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0029]     Certain embodiments of the present invention will be described in greater detail with reference to the accompanying drawings.  
         [0030]     The matters defined in the description, such as a detailed construction and elements thereof, are provided to assist in a comprehensive understanding of the invention. Thus, it is apparent that the present invention may be carried out without those defined matters. Also, well-known functions or constructions are not described in detail to provide a clear and concise description.  
         [0031]     Hereinafter, a wet-type electrophotographic image forming apparatus according to an embodiment of the present invention is described in detail with reference to the attached drawings.  
         [0032]      FIG. 2  is a schematic view of a wet-type electrophotographic image forming apparatus according to an exemplary embodiment of the present invention. Referring to  FIG. 2 , the wet-type electrophotographic image forming apparatus includes an image forming apparatus body  110 , a plurality of developing units  160  supplying ink to photosensitive bodies  120  to form images, ink cartridges  150  storing the ink, and fitting units  200 .  
         [0033]     The image forming apparatus body  110  encloses components of the wet-type electrophotographic image forming apparatus, such as the developing units  160 , the ink cartridges  150  and the fitting units  200 , and includes doors  112  (refer to  FIGS. 4 and 5 ) installed at ends thereof to open and close the ink cartridges.  
         [0034]     The developing units  160  are installed above the ink cartridges  150  and transfer the ink to the photosensitive bodies  120  to form the images. The ink fed from the ink cartridges  150  to the developing units  160  form the images on the photosensitive bodies  120 , and then the remaining ink is withdrawn to the ink cartridges  150 .  
         [0035]     A reference numeral  180  denotes an intermediate transfer belt, and reference numeral  170  denotes backup rollers supporting the transfer belt  180  to transfer the images from the photosensitive bodies  120  to the intermediate transfer belt  180 . A reference character P denotes a paper transferring path.  
         [0036]     Referring to  FIG. 3 , the ink cartridge  150  includes a cylinder-shaped housing  151 , a drainpipe inlet  152  formed in the housing  151 , and a transferring bar  250  installed inside the housing  151  in a horizontal direction (direction ‘A’ indicated by an arrow). The drainpipe inlet  152  is formed in an upper surface of the housing  151 , and a drainpipe  210  of the fitting unit  100  is withdrawn from or inserted into the drainpipe inlet  152  as shown in  FIGS. 4 and 5 . The transferring bar  250  is moveably installed in an inner upper portion of the ink cartridge  150  in the horizontal direction and includes a first end  251  protruding toward the door  112  as shown in  FIG. 4  and a second end  252  moving together with a coupling member  260  of the fitting unit  200  that will be described later. Referring to  FIG. 2 , the ink cartridges  150  respectively store different color inks, such as yellow (Y), magenta (M), cyan (C) and black (B), in spaces enclosed by the housings  151  and supply the different color inks to the developing units  160 , respectively.  
         [0037]      FIG. 4  is an enlarged elevational view in partial cross section of the coupling of the developing unit  160 , the ink cartridge  150 , and the fitting unit  200  of  FIG. 2 . Referring to  FIG. 4 , the fitting unit  200  includes the drainpipe  210  and a drainpipe transferring unit  290 .  
         [0038]     The drainpipe  210  includes an upper portion inserted into the developing unit  160  and a lower portion protruding outside the developing unit  160 . The drainpipe  210  serves as a flow path of the withdrawn ink and moves downward when the ink cartridge  150  is mounted in the image forming apparatus body  110  and the door  112  is closed so that the lower portion thereof is inserted into the ink cartridge  150  through the drainpipe inlet  152 . A supporting portion  212  having a predetermined radius is formed at a top end of the drainpipe  210 . Thus, when the drainpipe  210  moves downwardly, the supporting portion  212  is hooked on an upper surface  281  of a holder  280  and thus cannot move to a predetermined depth or more, as shown in  FIG. 5 . Since the drainpipe  210  vertically moves up and down, the drainpipe  210  may be formed of a material that is not rusted and bent. Also, the drainpipe  210  may be formed so that the inner area thereof is not changed.  
         [0039]     The drainpipe transferring unit  290  includes the holder  280 , an elastic member  220 , a flexible film  230 , a wire  240 , the coupling member  260 , and a guide member  270 .  
         [0040]     The holder  280  includes an upper portion fixed to a housing  161  of the developing unit  160  and a hole through which the drainpipe  210  penetrates. An elastic member housing hole  284  into which the elastic member  220  is inserted is formed between an inner wall  282  and an outer wall  283  of the holder  280 .  
         [0041]     The elastic member  220  includes an end fixed to the supporting portion  212  of the drain pipe  210  and the other end penetrating through the elastic member housing hole  284  of the holder  280  so as to be fixed to a lower end of the elastic member housing hole  284 . When the ink cartridge  150  is not mounted in the image forming apparatus body  110  ( FIG. 2 ) or when the door  112  is unclosed although the ink cartridge  150  is mounted ( FIG. 4 ), the elastic member  220  keeps a height of the drainpipe  210  inserted into the developing unit  160  to be higher than a head height H of the remaining ink. As a result, the ink remaining in the developing unit  160  cannot flow out from the developing unit  160 .  
         [0042]     The flexible film  230  includes an end fixed to an end of the supporting portion  212  of the drainpipe  210  and the other end fixed to the upper surface  281  of the holder  280 . The flexible film  230  prevents the ink from flowing between the drainpipe  210  and the holder  280 . Thus, the drainpipe transferring unit  290  including the elastic member  220 , the holder  280 , and the like is isolated from the ink and thus may be substantially prevented from malfunctioning due to sticking of the ink thereto. The flexible film  230  moves with the up and down movements of the drainpipe  210  and substantially prevents the ink from flowing in and out. Thus, the flexible layer  230  may be formed of a flexible film.  
         [0043]     The wire  240  includes an end fixed to a top end of the supporting portion  212  of the drainpipe  210 . The wire  240  penetrates through the supporting portion  212  and the inner wall  282  of the holder  280  so that the other end thereof penetrates through and is fixed to the coupling member  260 . The wire  240  moves with the movement of the coupling member  260  in direction ‘A’ indicated by an arrow, and thus the drainpipe  210  vertically descends in direction ‘B’ indicated by an arrow. Thus, the lower portion of the drainpipe  210  is inserted into the ink cartridge  150  through the drainpipe inlet  152 . As described above, since the wire  240  pulls the drainpipe  210  due to the movement of the coupling member  260 , the wire  240  may be formed of a metallic material that does not lengthen.  
         [0044]     The coupling member  260  is installed so that a side of a lower portion thereof contacts the end  252  of the transferring bar  250 . The wire  240  is fixed to a side of an upper portion of the coupling member  260 . As the transferring bar  250  moves in the direction ‘A’, the coupling member  260  contacting the transferring member  250  also moves in the direction ‘A’. The guide member  270  includes a guide rail  272  housing the upper portion of the coupling member  260  to guide a horizontal movement of the coupling member  260 .  
         [0045]     The operation of combining the developing unit  160 , the fitting unit,  200 , and the ink cartridge  150  is described below with reference to  FIGS. 2 through 5 .  
         [0046]     When the developing unit  160  and the ink cartridge  150  are not mounted in the image forming apparatus body  110  or when the door  112  is not closed although the developing unit  160  and the ink cartridge  150  are mounted, as shown in  FIG. 4 , the drainpipe  210  of the fitting unit  200  is higher than the head height H of the ink inside the developing unit  160  due to an elastic force of the elastic member  220 .  
         [0047]     When the door  112  is closed, the transferring bar  250  is pushed in the direction ‘A’. Thus, the coupling member  260  contacting the transferring bar  250  is also pushed in the direction ‘A’ as shown in  FIG. 4 . The wire  240  moves with the movement of the coupling member  260  to pull the drainpipe  210  downwardly in the direction ‘B’. Thus, the drainpipe  210  vertically descends in response to a horizontal movement distance of the transferring bar  250  to be inserted in the ink cartridge  150  through the drainpipe inlet  152 . As shown in  FIG. 5 , the supporting portion  212  of the drainpipe  210  is hooked on and fixed to a top end of the holder  280 , and the ink inside the developing unit  160  is withdrawn through the drainpipe  210  to the ink cartridge  150 . Although not described or shown in the present embodiment, an additional sealing member may be installed in the drainpipe inlet  152  so as to prevent the ink inside the ink cartridge  150  from flowing out from the ink cartridge  150  when the coupling member  260  is inserted into the drainpipe inlet  152 .  
         [0048]     When the door  112  is opened to replace or inspect the ink cartridge  150 , the drainpipe  210  ascends. Since a force of pulling down the wire  240  is removed, the drainpipe  210  ascends due to the elastic force of the elastic member  220 , and the ink remaining in the developing unit  160  does not flow through the drainpipe  210  into the ink cartridge  150 .  
         [0049]     As described above, in a wet-type electrophotographic image forming apparatus according to the present invention, ink inside a developing unit is vertically withdrawn through a drainpipe to an ink cartridge without changing an ink flowing path or the area of the ink flowing path. Thus, the ink flowing path is substantially prevented from becoming clogged and the ink is substantially prevented from sticking to the ink flowing path. As a result, the ink is substantially prevented from overflowing in the developing unit.  
         [0050]     Also, a pump is not used to withdraw the ink. Thus, the wet-type electrophotographic image forming apparatus has a simple structure, and thus the price of the wet-type electrophotographic image forming apparatus is lowered. Additionally, the developing unit, a fitting unit, and the ink cartridge may be coupled to one another by simply closing a door of an image forming apparatus body.  
         [0051]     The foregoing embodiment and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching may be readily applied to other types of apparatuses. Also, the description of the embodiments of the present invention is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.