Abstract:
An ink cartridge and a wet-type electrophotographic image forming apparatus having the ink cartridge, wherein the ink cartridge is detachably mounted with respect to an image forming apparatus body and supplies a developing unit with ink. The ink cartridge includes a housing including an inflow inlet into which the ink flows, and an inflow inlet opening and closing unit for operating together with the image forming apparatus body such that when the housing is mounted in the image forming apparatus body the inflow inlet is opened, and when the housing is removed from the image forming apparatus body the inflow inlet is closed. The inflow inlet opening and closing unit includes a moving member installed in the housing so as to move in first and second directions, at least one expanding tube bag installed in the inflow inlet for expanding and/or shrinking, depending on an inflow amount of liquid, to open and/or close the inflow inlet, and a liquid feeding unit for selectively feeding the liquid to and withdrawing the liquid from the at least one expanding tube bag depending on a movement direction of the moving member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2004-0064113, filed in the Korean Intellectual Property Office on Aug. 14, 2004, 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 an ink cartridge for feeding an ink to a developing unit or for withdrawing the ink from the developing unit, and a wet-type electrophotographic image forming apparatus having the same.  
         [0004]     2. Description of the Related Art  
         [0005]     In general, 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 have their own advantages. However, the wet-type image forming apparatuses can obtain a clearer, higher resolution printed material than the dry-type image forming apparatuses. In particular, with the increasing popularization of digital cameras, such a clearer, high quality natural color printed material is required. Thus, color image forming apparatuses have been increasingly demanded.  
         [0006]     However, in such a wet-type image forming apparatus, a much larger amount of developer than necessary for substantial printing must be fed to a developing unit performing a developing process to obtain satisfactory printing quality. Thus, developer that is not 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 for 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  for feeding ink to the developing units  16  and for withdrawing ink from the developing units  16 , and fitting units  20  for coupling the developing units  16  and the ink cartridges  15 . Reference numeral  18  denotes an intermediate transfer belt, and reference numeral  17  denotes transfer backup rollers for supporting the intermediate transfer belt  18  so as to transfer the images from the photosensitive bodies  12  to the intermediate transfer belt  18 . Reference character P denotes a paper transferring path.  
         [0008]     The fitting units  20  include coupling tubes  25  for forming flow paths for the ink, nut and bolt fitting portions  21  and  22  for coupling the developing units  16  and the coupling tubes  25 , nut and bolt fitting portions  23  and  24  for coupling the ink cartridges  15  and the coupling tubes  25 , and withdrawing pumps  26 .  
         [0009]     A process of circulating the ink in the wet-type electrophotographic image forming apparatus having the above-described structure will now be described in greater detail. 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 the feeding pumps (not shown). However, after a predetermined developing process is performed, all the ink may not be used for a printing operation and some ink may remain in the developing units  16 . The remaining ink is then withdrawn to the ink cartridges  15  through the withdrawing pumps  26  and the coupling tubes  25 .  
         [0010]     Coupling apparatuses, therefore, are necessarily required between the developing units  16  and the ink cartridges unit  15  to circulate the wet ink. Also, the airtightness of the coupling apparatuses is very important in terms of the characteristics of the wet ink. In addition, while the ink cartridges  15  containing the ink are being mounted in or withdrawn from an image forming apparatus body, the ink must not flow from the ink cartridges  15 . 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 elastic members, are generally well adapted for airtight use with the developing unit  16  and the ink cartridge  15 .  
         [0011]     However, the above-mentioned coupling apparatuses include additional power sources such as pumps and other nut and bolt fitting portions. Thus, the structure of the coupling apparatuses is complicated and the manufacturing costs for the coupling apparatuses is increased. Moreover, the nut and bolt fitting portions  23  and  24  must be manually combined to couple the fitting units  20  and the ink cartridges  15 .  
         [0012]     Furthermore, during the ink withdrawing process, the flow paths of the ink between the fitting units  20  and the ink cartridges  15  may be curved, and the area of the flow paths may be suddenly reduced. Thus, the ink may stick to the flow paths. As a result, the flow paths may become clogged, or functions of combining, opening or closing the fitting units  20  may be lost. In particular, this may frequently occur in places where the nut fitting portions  21  and  22  and the bolt fitting portions  23  and  24 , are combined. In a case where nut and bolt fitting portions or coupling tubes are clogged, ink may be continuously fed to the developing units  16 , but not withdrawn from the developing units. Thus, the ink may overflow in the developing units  16 . The overflowing ink may then 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 become seriously contaminated.  
         [0013]     Accordingly, a need exists for an ink cartridge system such that efficient and effective ink flow can be maintained, while further maintaining the airtight characteristics of the ink cartridge.  
       SUMMARY OF THE INVENTION  
       [0014]     Accordingly, the present invention has been made to solve the above-mentioned and other problems. An aspect of the present invention is to provide an improved ink cartridge that is capable of maintaining airtightness during an image forming process, as well as when the ink cartridge is being easily mounted in or removed from an image forming apparatus body, and a wet-type electrophotographic image forming apparatus having the same.  
         [0015]     According to an aspect of the present invention, an ink cartridge is provided that is detachably mounted with respect to an image forming apparatus body for supplying a developing unit with ink and comprising a housing including an inflow inlet into which the ink flows, and an inflow inlet opening and closing unit for operating together with the image forming apparatus body such that when the housing is mounted with the image forming apparatus body the inflow inlet is opened, and when the housing is removed from the image forming apparatus body the inflow inlet is closed.  
         [0016]     The inflow inlet opening and closing unit may include a moving member installed in the housing so as to move in first and second directions, at least one expanding tube bag installed in the inflow inlet for expanding and/or shrinking, depending on an inflow amount of liquid, to open and/or close the inflow inlet, and a liquid feeding unit for selectively feeding the liquid to and withdrawing the liquid from the at least one expanding tube bag depending on a movement direction of the moving member.  
         [0017]     The liquid feeding unit may include a bellows coupled to the moving member for storing the liquid, and a liquid transferring pipe for coupling the bellows and the at least one expanding tube bag.  
         [0018]     The inflow inlet opening and closing unit may further include an elastic member for elastically pressing the moving member toward the first direction so as to expand the at least one expanding tube bag. When the moving member is mounted in the image forming apparatus body, the moving member may then be moved by the image forming apparatus body in the second direction.  
         [0019]     The inflow inlet opening and closing unit may further include a pair of rubber covers installed on an inner wall of the inflow inlet to face each other so as to maintain a closed portion of the inflow inlet independently.  
         [0020]     A pair of expanding tube bags may be provided and supported by the pair of rubber covers, respectively, to close a remaining portion of the inflow inlet.  
         [0021]     The inflow inlet opening and closing unit may further include a pair of sealing bags installed on an inner circumference of the inflow inlet to face each other and being positioned between the expanding tube bags so as to prevent a gap from being generated between a point at which the expanded tube bags contact each other and contact the inner circumference of the inflow inlet.  
         [0022]     A drainpipe may be coupled to the inflow inlet to withdraw the ink used in the developing unit, and a sealing member may be installed in the inflow inlet for sealing between an outer circumference of the drainpipe and an inner circumference of the inflow inlet when the drainpipe is inserted into the inflow inlet.  
         [0023]     The sealing member may include a flexible film coupled to the inner circumference of the inflow inlet and comprise a cavity through which the drainpipe passes, and a flexible wire formed at an edge of the cavity of the flexible film to be thicker than the flexible film.  
         [0024]     According to another aspect of the present invention, a wet-type electrophotographic image forming apparatus is provided comprising an image forming apparatus body including a developing unit for forming a predetermined image using ink and having an ink cartridge mounting portion, and an ink cartridge that is detachably mounted with respect to the ink cartridge mounting portion and including ink to be fed to the developing unit. The ink cartridge comprises a housing including an inflow inlet to which a drainpipe for withdrawing the ink from the ink cartridge is coupled, and an inflow inlet opening and closing unit for operating together with the ink cartridge mounting portion such that when the housing is mounted in the ink cartridge mounting portion the inflow inlet is opened, and when the housing is removed from the mounting portion the inflow inlet is closed.  
         [0025]     The inflow inlet opening and closing unit may include a moving member installed in the housing so as to move in first and second directions and, when being locked in the ink cartridge mounting portion, moves in the second direction, an elastic member for elastically pressing the moving member in the first direction, at least one expanding tube bag installed in the inflow inlet for expanding and/or shrinking depending on an inflow amount of liquid to open and/or close the inflow inlet, and a liquid feeding unit for selectively feeding the liquid to and withdrawing the liquid from the at least one expanding tube bag depending on a movement direction of the moving member.  
         [0026]     The at least one expanding tub bag may expand when being fed with the liquid from the liquid feeding unit as the moving member moves in the first direction, and may shrink when returning the liquid to the liquid feeding unit as the moving member moves in the second direction. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]     The above aspects and features of the present invention will become more apparent by describing certain embodiments of the present invention with reference to the accompanying drawings, in which:  
         [0028]      FIG. 1  is a schematic view of a conventional wet-type electrophotographic image forming apparatus;  
         [0029]      FIG. 2  is a schematic view of a wet-type electrophotographic image forming apparatus according to an embodiment of the present invention;  
         [0030]      FIG. 3  is a schematic perspective view of an ink cartridge that can be mounted in an image forming apparatus body according to an embodiment of the present invention;  
         [0031]      FIG. 4  is a plan view of the ink cartridge shown in  FIG. 3 ;  
         [0032]      FIG. 5  is a plan view of the ink cartridge of  FIG. 3  that is mounted in an image forming apparatus body according to an embodiment of the present invention;  
         [0033]      FIGS. 6A  to  7 B are plan views of an inflow inlet of the ink cartridge of  FIG. 3  in which a sealing member is installed and cross-sectional views of the inflow inlet according to an embodiment of the present invention; and  
         [0034]      FIG. 8  is a cross-sectional view of the inflow inlet of  FIG. 7  to which a drainpipe is coupled according to an embodiment of the present invention. 
     
    
       [0035]     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.  
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0036]     Certain exemplary embodiments of the present invention will now be described in greater detail with reference to the accompanying drawings.  
         [0037]     In the following description, same drawing reference numerals are used for the same elements even in different drawings. The matters defined in the description, such as detailed construction and element descriptions, are provided to assist in a comprehensive understanding of the invention. Also, functions or constructions well known to those skilled in the art are omitted for clarity and conciseness.  
         [0038]     Hereinafter, an ink cartridge according to an exemplary embodiment of the present invention and a wet-type electrophotographic image forming apparatus having the ink cartridge, will be described in detail with reference to the attached drawings.  
         [0039]      FIG. 2  is a schematic view of a wet-type electrophotographic image forming apparatus according to an 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  for feeding photosensitive bodies  120  with ink to form images, a plurality of ink cartridges  200  for storing the ink, and drainpipes  100  for coupling the developing units  160  and the ink cartridges  200 , respectively.  
         [0040]     The image forming apparatus body  110  encloses the components of the wet-type electrophotographic image forming apparatus such as the developing units  160 , the ink cartridges  200 , and the like, and includes a mounting portion  111  as shown in  FIG. 5  in which the ink cartridges  200  are mounted.  
         [0041]     The developing units  160  are installed above the ink cartridges  200  and transfer the ink to the photosensitive bodies  120  to form the images. The ink fed from the ink cartridges  200  to the developing units  160  serves to form the images on the photosensitive bodies  120 , and the remaining ink is withdrawn to the ink cartridges  200 .  
         [0042]     Reference numeral  180  denotes an intermediate transfer belt, and reference numeral  170  denotes transfer backup rollers for supporting the intermediate transfer belt  180  so as to transfer the images from the photosensitive bodies  120  to the intermediate transfer belt  180 . Reference character P denotes a paper transferring path.  
         [0043]     The drainpipes  100  are respectively coupled to the developing units  160  and couple the developing units  160  to the ink cartridges  200  when the ink cartridges  200  are mounted in the image forming apparatus body  110 . Accordingly, the drainpipes  100  serve as flow paths for the withdrawn ink.  
         [0044]     The ink cartridges  200  respectively store and feed different color ink, such as yellow (Y), magenta (M), cyan (C), and black (B) colored ink to the developing units  160 , as described in greater detail below.  
         [0045]      FIG. 3  is a schematic perspective view of an exemplary ink cartridge  200  that can be mounted in the image forming apparatus body  110  according to an embodiment of the present invention.  FIG. 4  is a plan view of the ink cartridge  200  of  FIG. 3 , and  FIG. 5  is a plan view of the ink cartridge  200  of  FIG. 3  when mounted in the image forming apparatus body  110  according to an embodiment of the present invention.  
         [0046]     The ink cartridge  200  includes a cylinder-shaped housing  210  including a drainpipe inlet  220  which is formed in an upper portion of the ink cartridge  200  and into which the drainpipe  100  is inserted, and a drainpipe inlet opening and closing unit  230  installed inside the housing  210  to open and close the drainpipe inlet  220 .  
         [0047]     The drainpipe inlet opening and closing unit  230  operates when the ink cartridge  200  is mounted in the image forming apparatus body  110  so as to open the drainpipe inlet  220 . The drainpipe inlet opening and closing unit  230  includes a stationary frame  231 , a liquid transferring pipe  236 , expanding tube bags  237 , rubber covers  238 , and sealing bags  239 . The stationary frame  231  is installed inside the housing  210  and includes a bellows  232 , an elastic member  233 , and a moving member  234 . A guide groove  231   a  is formed in an upper surface of the stationary frame  231  so that the moving member  234  moves along the guide groove  231   a.    
         [0048]     The bellows  232  includes nonvolatile oil or liquid, such as water. The liquid transferring pipe  236  is coupled to an end of the bellows  232  so as to transfer the liquid when the bellows  232  expands or shrinks.  
         [0049]     The moving member  234  is coupled to the other end of the bellows  232  and is formed on the stationary frame  231  to move along the guide groove  231   a . The moving member  234  may protrude outside the housing  210 . Protrusions  235  are formed at both ends of the moving member  234 . When the ink cartridge  200  is mounted in the mounting portion  111  formed in the image forming apparatus body  110 , the protrusions  235  interfere with a locking member  112  formed in the mounting portion  111  (refer to  FIG. 5 ).  
         [0050]     Since the elastic member  233  includes an end coupled to the stationary frame  231  and the other end coupled to the moving member  234 , the elastic member  233  presses the moving member  234  toward a predetermined direction.  
         [0051]     The liquid transferring pipe  236  is coupled to the bellows  232  and the expanding tube bags  237  so as to transfer liquid between each. In an exemplary embodiment shown, since two expanding tube bags  237  are installed, the liquid transferring pipe  236  includes two liquid paths branched therefrom. In yet other embodiments of the present invention, the number of expanding tube bags and liquid paths can be varied as required by the application.  
         [0052]     The expanding tube bags  237  are installed inside the drainpipe inlet  220  and expand or shrink depending on an inflow amount of liquid from the liquid transferring pipe  236  so as to open or close the drainpipe inlet  220 . As shown in  FIG. 4 , the two expanding tube bags  237  may face each other. The liquid transferring pipe  236  is coupled to the expanding tube bags  237 . Thus, when the liquid flows into the expanding tube bags  237  through the liquid transferring pipe  236 , the expanding tube bags  237  expand to close the drainpipe inlet  220  (see  FIG. 4 ). When the liquid flows from the expanding tube bags  237 , the expanding tube bags  237  shrink to open the drainpipe inlet  220  (see  FIG. 5 ). Accordingly, the expanding tube bags  237  may be formed of any suitable elastic material.  
         [0053]     The rubber covers  238  are installed on an inner wall of the drainpipe inlet  220  to face each other and respectively support the expanding tube bags  237 . The rubber covers  238  include liquid or gas, such as air, so as to maintain a predetermined volume. Thus, the rubber covers  238  maintain a closed portion of the drainpipe inlet  220  independently, such that the expanding tube bags  237  can rapidly open or close the remaining drainpipe inlet  220  opening depending upon the expanding or shrinking of the expanding tube bags  237 .  
         [0054]     The sealing bags  239  are installed on the inner wall of the drainpipe inlet  220  to face each other. The sealing bags  239  serve to fill a gap formed at an inner circumference of the drainpipe inlet  220  between the expanding tube bags  237  when the expanding tube bags  237  expand and contact each other to close the drainpipe inlet  220 . The drainpipe inlet  220  is circular. Thus, although the expanding tube bags  237  uniformly expand, the gap is formed in the drainpipe inlet  220 . However, the sealing bags  239  prevent the gap from being formed in the drainpipe inlet  220 .  
         [0055]     A sealing member  240  is further installed on the expanding tube bags  237  in the drainpipe inlet  220 . This is more clearly shown in  FIGS. 6A  to  7 B.  FIG. 6A  illustrates a plan view of the drainpipe inlet  220  in which a sealing member  240  is installed when the ink cartridge  200  is not mounted in the image forming apparatus body  110 , and  FIG. 6B  illustrates a cross-sectional view of the drainpipe inlet  220 , taken along line VI-VI of  FIG. 6A .  FIG. 7A  illustrates a plan view of the drainpipe inlet  220  in which the sealing member  240  is installed when the ink cartridge  200  is mounted in the image forming apparatus body  110 , and  FIG. 7B  illustrates a cross-sectional view of the drainpipe inlet  220 , taken along line VII-VII of  FIG. 7A .  
         [0056]     The sealing member  240  serves to seal the opening between an outer circumference of the drainpipe  100  shown in  FIG. 8 , and an inner circumference of the drainpipe inlet  220  when the drainpipe  100  is coupled to the drainpipe inlet  220 , and includes a flexible film  242  and a flexible wire  243 .  
         [0057]     The flexible film  242  is coupled to the inner circumference of the drainpipe inlet  220  and includes a cavity  244  through which the drainpipe  100  passes. The flexible wire  243  is thicker than the flexible film  242 , and is formed at the edge of the flexible film  242 . The flexible wire  243  may be elastically formed. Referring to  FIG. 8 , the drainpipe  100  is inserted into the drainpipe inlet  220  of  FIG. 7B  and the cavity  244  of the flexible film  242 . The flexible wire  243  serves to prevent the ink inside the ink cartridge  200  from flowing out of the ink cartridge  200 .  
         [0058]     The operation of the ink cartridge  200  will now be described in greater detail with reference to  FIGS. 3 through 8 .  
         [0059]     Referring to  FIGS. 4 and 6 B, when the ink cartridge  200  is not mounted in the image forming apparatus body  110 , the moving member  234  is pressed by an elastic force of the elastic member  233 . The liquid in the bellows  232  is compressed and flows into the expanding tube bags  237  through the liquid transferring pipe  236  so as to expand the expanding tube bags  237 . As a result of the expanding tube bags  237  and cooperating rubber covers  238  and sealing bags  239 , the drainpipe inlet  220  of the ink cartridge  200  is closed so that the ink in the ink cartridge  200  cannot flow out.  
         [0060]     Referring to  FIGS. 5 and 7 B, when the ink cartridge  200  is mounted in the mounting portion  111  of the image forming apparatus body  110  in the direction indicated by the arrow, the protrusions  235  of the moving member  234  are locked by the locking member  112  installed in the mounting portion  111 . Since the ink cartridge  200  continuously advances in the direction indicated by the arrow, the bellows  232  are expanded in an opposite direction relative to the direction along which the ink cartridge  200  is mounted. The liquid in the expanding tube bags  237  flows from the expanding tube bags  237  due to the expanding of the bellows  232 , and then flows into the bellows  232  through the liquid transferring pipe  236 . As a result, the expanding tube bags  237  shrink, and thus, a drainpipe entry path  222  is formed between the expanding tube bags  237 .  
         [0061]     Referring to  FIG. 8 , when the ink cartridge  200  is completely mounted in the image forming apparatus body  110 , the drainpipe  100  coupled to the developing unit  160  shown in  FIG. 2  descends from the developing unit  160  and is inserted into the ink cartridge  200  through the drainpipe inlet  220  of the ink cartridge  200 . As a result, the ink in the developing unit  160  is withdrawn from the developing unit  160  into the ink cartridge  200  through the drainpipe  100  along a direction indicated by the arrow.  
         [0062]     As described above, an ink cartridge and a wet-type electrophotographic image forming apparatus having the ink cartridge can be provided according to the present invention such that when the ink cartridge is not mounted in the image forming apparatus body, an ink inflow inlet can be automatically closed and sealed. When the ink cartridge is mounted in the image forming apparatus body, the inflow inlet can be automatically opened while maintaining the airtight characteristics of the ink cartridge using a sealing member.  
         [0063]     Also, when the ink cartridge is mounted in or removed from the image forming apparatus body, the inflow inlet can be automatically opened or closed in response. Thus, the ink cartridge can be conveniently mounted in the image forming apparatus body. Also, when the ink cartridge is coupled to a drainpipe of a developing unit, an inflow path can be provided that will not suddenly shrink or expand. Therefore, the ink will not clog the inflow path of the ink cartridge.  
         [0064]     Moreover, a drainpipe inlet can be opened or closed using an oil pressure. Thus, the drainpipe inlet can be opened or closed regardless of any drying or sticking of the ink on the surfaces of expanding tube bags.  
         [0065]     The foregoing embodiments and advantages are merely exemplary, and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. Also, the descriptions of the embodiments of the present invention are 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.