Abstract:
A pair of cleaning apparatuses for a liquid electrophotographic printer that can completely remove to residual toner from both a photo receptor belt and a transfer roller, respectively. Each cleaning apparatus is supplied with a liquid solvent used to dissolve toner remaining on the transfer roller and the photo receptor belt after a printing operation. Each of the pair of cleaning apparatuses can engage and disengage to and from the photo receptor belt and the transfer roller respectively upon user actuation or entry of a sheet of recording media into the electrophotographic printing apparatus. Each cleaning apparatus contains in rectangular felt material soaked with solvent positioned to mate with the surfaces of the photo receptor belt and the transfer roller.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid electrophotographic printer, and more particularly, to a cleaning apparatus for removing various contaminants containing untransferred toner remaining on a photoreceptor belt and/or a transfer roller after printing, using a cleaning member having a solvent, and a liquid electrophotographic printer having the cleaning apparatus. 
     Here, printers generally refer to all kinds of image printing apparatuses for printing an image using an electrophotographic process, for example, copiers, facsimile apparatuses or the like, as well as general laser printers. 
     2. Description of the Related Art 
     In general, a liquid electrophotographic printer forms an electrostatic latent image on a photosensitive medium such as a photoreceptor belt by scanning a laser beam onto the photoreceptor belt, develops the electrostatic latent image formed on the photoreceptor belt using a developer liquid, which is a mixture of solid toner of a predetermined color and liquid carrier serving as a solvent, and transfers the developed image to a printing sheet, thereby printing a desired image. 
     The liquid electrophotographic printer typically have two parts; an engine which consists of essential parts for performing a printing process, and a controller for interpreting data transmitted from a data outputting device such as a computer, constructing to-be-printed image data by individual bits of a one-page size to then be stored in a video RAM, communicating with the engine so as to perform printing and then transmitting the data stored in the video RAM to the engine in the form of serial data. 
     An exemplary liquid electrophotographic printer having the aforementioned configuration is schematically shown in FIG. 1, which will now be described briefly. 
     As illustrated, the liquid electrophotographic printer includes a photoreceptor belt  10  wound around and supported by rollers  1 ,  2  and  3  which are installed within a printer body and traveling along a predetermined track. 
     In the neighborhood of the photoreceptor belt  10  are installed an erasure unit  20  for erasing the surface potential formed on the photoreceptor belt  10 , a charging unit  30  for charging the photoreceptor belt  10  from which the surface potential has been erased, to a predetermined potential, an exposure unit  40  for forming an electrostatic latent image by scanning a laser beam converted according to electric data of a portion to be printed, onto the photoreceptor belt  10 , a development unit  50  for supplying a developer liquid, which is a mixture of solid toner and liquid carrier, to the photoreceptor belt  10  to thus adhere the toner to a portion of the surface of the photoreceptor belt  10  where the electrostatic latent image is formed, thereby forming a visible image, a drying unit  60  for absorbing only the carrier contained in the developer liquid other than the toner adhered to the photoreceptor belt  10 , drying and removing the same, a transfer/fixation unit  70  for transferring the toner formed on the photoreceptor belt  10  as an image, to a printing sheet  80 . 
     Inside the photoreceptor belt  10  are installed a plurality of backup rollers  4 ,  5 ,  6  and  7  in close contact with the photoreceptor belt  10  to then be passively driven. 
     Also, the exposure unit  40  includes four laser scanning units (LSUs)  41 ,  42 ,  43  and  44  corresponding to various colors, for example, yellow (Y), magenta (M), cyan (C) and black (K), respectively. 
     The development unit  50  includes four development rollers  51 ,  52 ,  53  and  54  rotating selectively in close contact with the photoreceptor belt  10 , and squeegee rollers  51 ′,  52 ′,  53 ′ and  54 ′ installed next to the development rollers  51 ,  52 ,  53  and  54 , respectively. 
     The drying unit  60  includes a dry roller  62  rotatably installed in a bracket (not shown) provided inside a manifold  61 , and a pair of heating rollers  63  and  63 ′ selectively in close contact with the dry roller  62 . 
     The transfer/fixation unit  70  includes a transfer roller  71  selectively brought into close contact with the photoreceptor belt  10 , and a fixation roller  72  selectively brought into close contact with the transfer roller  71 . The printing sheet is fed between the transfer roller  71  and the fixation roller  72 . At this stage, the image transferred to the transfer roller  71  is conveyed to the printing sheet  80 . The fixation roller  72  fuses the toner image to then be adhered to the printing sheet  80  by applying heat and pressure to the toner image conveyed to the printing sheet. 
     Although not shown, the liquid electrophotographic printer further includes a developer liquid supplying device for continuously supplying a developer liquid having a predetermined concentration to the development unit  50 , a sheet feeding unit for supplying printing sheets and a sheet ejection unit. 
     The printing process of the aforementioned liquid electrophotographic printer is performed as follows. 
     If a printing instruction is input from a data outputting device such as a computer, the erasure unit  20  first operates to electrically clear the residual charges remaining on the photoreceptor belt  10 . Then, the charging unit  30  applies a high voltage to the photoreceptor belt  10  to charge the surface thereof to a predetermined potential (generally 500 to 700 V). 
     Next, the exposure unit  40  scans a laser beam converted according to the electric data of a portion to be printed on the photoreceptor belt  10  charged to the predetermined potential, thereby forming an electrostatic latent image on the photoreceptor belt  10  due to a difference in the surface potential. 
     After exposure, the development unit  50  performs development, in which the electrostatic latent image formed on the photoreceptor belt  10  is converted into a visible image using toner particles. The development unit  50  adheres the toner contained in an externally supplied developer liquid to the portion of the photoreceptor belt  10  where the electrostatic latent image is formed, thereby forming the visible image on the photoreceptor belt  10 . Here, the liquid carrier contained in the developer liquid is squeezed simultaneously with development to then be primarily separated for removal. 
     The surplus carrier which is not removed by the development unit  50  is absorbed by the dry roller  62  while the photoreceptor belt  10  passes through the drying unit  60 , and then evaporated by a pair of heating rollers  63  and  63 ′ for removal, so that the toner image formed on the photoreceptor belt  10  becomes a suitable image to be transferred. 
     The toner image developed on the photoreceptor belt  10  through the above-described process is transferred to the transfer roller  71  via the transfer/fixation unit  70 . The image transferred to the transfer roller  71  is conveyed to the printing sheet  80  fed between the transfer roller  71  and the fixation roller  72 , and are completely fused to then be fixed to the printing sheet  80  when heat and pressure are applied by the fixation roller  72 . 
     During the above-described process, transferring an image, for example, from the photoreceptor  10  to the transfer roller  71  or from the transfer roller  71  to the printing sheet  80 , is performed due to a difference in the surface energy, that is, a difference in the adhesion, between each of the photoreceptor belt  10 , the transfer roller  71  and the printing sheet  80 . In other words, since the adhesion of the photoreceptor belt  10  is set to be relatively higher than that of the transfer roller  71 , and the adhesion of the printing sheet  80  is set to be higher than that of the transfer roller  71 , the toner image of the photoreceptor belt  10  is transferred to the transfer roller  71  and is finally transferred to the printing sheet  80 . 
     Here, it is desirable that the image of the photoreceptor belt  10  is completely transferred to the transfer roller  71  and that the image of the transfer roller  71  is completely transferred to the printing sheet  80 . However, in an actual printing process, the adhesion between the photoreceptor belt  10  and the transfer roller  71  and the adhesion between the transfer roller  71  and the printing sheet  80  are not maintained at appropriate levels. Thus, some of the image of the photoreceptor belt  10  may remain on the photoreceptor belt  10 , without being completely transferred to the transfer roller  71 . Also, some of the image of the transfer roller  71  may remain on the transfer roller  71 , without being completely transferred to the printing sheet  80 . 
     As described above, in the case where untransferred toner remains on the photoreceptor belt  10 , the toner may overlap with an image to be printed next, resulting in deterioration of picture quality. Also, if the untransferred toner is hardened on the photoreceptor belt, the portion of the photoreceptor belt bearing hardened toner cannot be used, which unavoidably causes deterioration of picture quality. Also, the toner remaining on the photoreceptor belt is used in development of a subsequent image to thus contaminate ink and also causes contamination to the dry roller. Thus, the untransferred toner remaining on the photoreceptor belt must be removed. 
     The aforementioned problems may also be encountered in the case where untransferred toner remains on the transfer roller  71 . Moreover, since the contamination of the transfer roller  71  may adversely affect picture quality, the contamination of the transfer roller  71  must be eliminated. 
     To this end, in the conventional printer, as shown in FIG. 1, there is provided a cleaning apparatus for removing ink sludge sticking to or remaining on the transfer roller  71 , by installing a separate cleaning roller  90  in the neighborhood of the transfer roller  71  to be selectively brought into close contact with the transfer roller  71 . This cleaning apparatus can also be used for cleaning the photoreceptor belt  10  in the following manner. 
     That is to say, after printing, the fixation roller  72  is separated from the transfer roller  71  and then the untransferred toner remaining on the photoreceptor belt  10  is made to be transferred to the transfer roller  71  while operating the cleaning roller  90  in close contact with the transfer roller  71 . Then, the transfer roller  71  is cleaned using the cleaning roller  90 , thereby removing the contaminants, that is, untransferred toner, of the photoreceptor belt  10 . 
     However, the aforementioned cleaning apparatus of a general liquid electrophotographic printer, which is configured such that untransferred toner remaining on a photoreceptor belt is first transferred to a transfer roller and the contaminants transferred to the transfer roller are then removed, has a problem in that there is a limit in removing the contamination of the photoreceptor belt, that is, the toner which is not transferred from the photoreceptor belt to the transfer roller during a cleaning process, cannot be removed. 
     Also, since the conventional cleaning apparatus is a dry type in which the surface of a transfer roller is wiped out by simply bringing a cleaning roller into close contact with the transfer roller, the contaminants containing untransferred toner remaining on a photoreceptor belt are not completely removed. Also, the adhesion of the transfer roller may be weakened so that the untransferred toner on the photoreceptor belt cannot be transferred to the transfer roller, thereby obstructing effective removal of contaminants of the photoreceptor belt. 
     Further, since the conventional cleaning apparatus is configured to remove contaminants of a photoreceptor belt by being driven in a separate cleaning mode after printing, a separate cleaning time is required. Thus, the overall time required for printing increases. Also, since the contamination of the photoreceptor belt cannot be removed during a continuous printing process, the deterioration of picture quality, which is due to contamination of the photoreceptor belt, cannot be avoided. 
     SUMMARY OF THE INVENTION 
     To solve the above problems, it is a first object of the present invention to provide a cleaning apparatus of a liquid electrophotographic printer which can effectively remove various contaminants containing untransferred toner remaining on a photoreceptor belt, by performing a cleaning operation in direct contact with the photoreceptor belt. 
     It is a second object of the present invention to provide a cleaning apparatus of a liquid electrophotographic printer which can dissolve untransferred toner remaining on a photoreceptor belt and on a transfer roller and completely remove the same, by bringing a cleaning member containing a liquid solvent into contact with the photoreceptor belt and the transfer roller. 
     It is a third object of the present invention to provide a cleaning apparatus of a liquid electrophotographic printer which can reduce a printing time by continuously performing a cleaning operation such that the cleaning apparatus is brought into contact with a photoreceptor belt simultaneously with printing by the printer, without a separate cleaning time being required, and which can effectively remove various contaminants containing untransferred toner remaining on the photoreceptor belt even while the printing is continuously performed. 
     It is a fourth object of the present invention to provide a liquid electrophotographic printer having the cleaning apparatus, by which deterioration of picture quality due to contamination of a photoreceptor belt and a transfer roller can be prevented and a clean picture image can be obtained. 
     To solve the above objects of the present invention, there is provided a cleaning apparatus of a liquid electrophotographic printer includes a photoreceptor belt contamination removing means which is brought into close contact with the surface of the photoreceptor belt simultaneously with a printing operation, for removing contaminants containing untransferred toner of the photoreceptor belt, and a transfer roller contamination removing means which is brought into close contact with the surface of the transfer roller simultaneously with a printing operation, for removing contaminants containing untransferred toner of the transfer roller. Here, the photoreceptor belt contamination removing means is installed between a transfer/fixation unit and a charging unit in the neighborhood of a photoreceptor belt of the liquid electrophotographic printer. 
     Also, the cleaning apparatus may further include a solvent supplying means for continuously supplying a solvent to the photoreceptor belt contamination removing means and the transfer roller contamination removing means so that the respective contamination removing means containing the solvent dissolve the untransferred toner to then be removed. Accordingly, the contaminants containing untransferred toner of the photoreceptor belt and the transfer roller can be more effectively removed. 
     The photoreceptor belt contamination removing means preferably includes a cleaning member assembly selectively brought into close contact with the surface of the photoreceptor belt, for wiping out the contaminants of the photoreceptor belt, a housing for supporting the cleaning member assembly, a means for making the cleaning member assembly closely contact and/or separate from the surface of the photoreceptor belt by moving the cleaning member assembly relative to the housing, and a frame fixed to the printer body, for detachably supporting the housing. 
     The cleaning member assembly includes a cleaning member, a pair of fixing blocks coupled to both ends of the cleaning member and a bracket integrally coupled to the pair of fixing blocks. 
     Here, the cleaning member is formed by stacking a plurality of thin rectangular felts on a fixing plate having a pair of fixing pieces, and a cleaning sheet, which is brought into direct contact with the photoreceptor belt during a cleaning operation, is fixed to the bottom surface of the cleaning member. Also, a pair of fixing pieces are formed at both ends of the fixing plate. 
     Also, fixing parts for fixing the fixing pieces of the cleaning member and threaded holes piercing downward, are formed in the fixing blocks, respectively. Springs for elastically supporting the pair of fixing blocks downward with respect to the housing are installed in the threaded holes. Further, adjustment threads are upwardly engaged with the threaded holes, for supporting the springs and adjusting the elasticity thereof. 
     The cleaning member contacting and separating means may include a movement shaft installed to be capable of moving axially through the openings formed on the fixing blocks, a plurality of operating protrusions protruding at three or more locations of the movement shaft in the radial direction thereof, and cam grooves each having a predetermined inclined portion, formed on one side of the holder bracket. If the movement shaft is axially moved, the cleaning member assembly ascends or descends with respect to the housing by the action of the operating protrusions and the cam grooves of the holder bracket. Accordingly, the cleaning member assembly can closely contact and/or separate from the photoreceptor belt. 
     Circular holes into which the movement shaft is inserted are formed at both ends of the housing, respectively, and guiding slots for guiding movement of the operating protrusions piercing cam grooves of the bracket and protruding are formed at locations corresponding to the cam grooves on the rear surface of the housing. Also, guide rails are formed on the front and rear surfaces of the housing and slide grooves into which the guide rails of the housing are inserted, are formed in the frame. Thus, the housing can be detachably installed in the frame. 
     The transfer roller contamination removing means may include a cleaning member assembly selectively brought into close contact with the transfer roller, for wiping out the contaminants of the transfer roller, a frame fixed to a printer body and having each pair of first and second guiding holes formed on its top surface and guiding slots formed at either lateral side thereof, for supporting the cleaning member assembly, and a means for making the cleaning member assembly closely contact and/or separate from the transfer roller by moving the cleaning member assembly relative to the frame. 
     The cleaning member assembly includes a cleaning member formed by stacking a plurality of thin rectangular felts having different heights and having an arcuate lower profile corresponding to the outer circumferential surface of the transfer roller, formed under the stack of the felts, a holder for fixing the cleaning member and having guiding protrusions inserted into guiding slots of the frame, and a holder bracket integrally coupled to the holder and having on the top surface thereof a pair of guide bars piercing a pair of first guiding holes formed on the frame. 
     Also, the cleaning member contacting and separating means may include a pair of movement bars piercing the second guiding holes to then be fixed to the holder bracket at both ends thereof, springs interposed between the pair of movement bars, for elastically supporting the holder bracket downward with respect to the frame, and a movement lever movably installed to be capable of rotating relative to the movement bars upward protruding with respect to the frame by means of a pin. Here, if the movement lever is rotated in one direction, it gets laid down with respect to the frame so that the holder bracket is pushed by the springs and the cleaning member is brought into close contact with the transfer roller accordingly. If the movement lever is rotated in a reverse direction, it erects with respect to the frame so that the holder bracket is pulled toward the frame in spite of the elasticity of the springs and the cleaning member is separated from the transfer roller accordingly. 
     The solvent supplying means may include a solvent storage tank installed at one side of the printer body, for storing a solvent, and a solvent conveying member installed to be led from the solvent storage tank to be connected to the photoreceptor belt contamination removing means and the transfer roller contamination removing means, for continuously conveying the solvent stored in the solvent storage tank to the cleaning members of the respective contamination removing means. 
     Accordingly, since the photoreceptor belt is cleaned by the cleaning member in direct contact with the surface of the rotating photoreceptor belt, various contaminants containing untransferred toner which is not transferred to the transfer roller and remains on the photoreceptor belt can be effectively removed. 
     Further, since the photoreceptor belt and the transfer roller are cleaned by the cleaning members containing the solvent which are in close contact with the photoreceptor belt and the transfer roller, various contaminants containing untransferred toner remaining on the photoreceptor belt and the transfer roller can be perfectly removed. 
     According to another aspect of the present invention, there is provided a liquid electrophotographic printer including a photoreceptor belt wound around and supported by a plurality of rollers which are installed within a printer body and traveling along a predetermined track, a charging unit for charging the surface potential erased photoreceptor belt to a predetermined potential, an exposure unit for forming an electrostatic latent image on the photoreceptor belt by scanning onto the photoreceptor belt a laser beam converted according to electric data of a portion to be printed, a development unit for supplying a developer liquid which is a mixture of solid toner and liquid carrier to the photoreceptor belt to adhere the toner to a portion on the surface of the photoreceptor belt where the electrostatic latent image is formed, thereby forming a visible image, a drying unit for absorbing, drying and removing only the carrier contained in the developer liquid other than the toner adhered to the photoreceptor belt, a transfer/fixation unit for transferring the toner formed on the photoreceptor belt as an image to a printing sheet, a photoreceptor belt contamination removing means installed between a transfer/fixation unit and a charging unit in the neighborhood of a photoreceptor belt of the liquid electrophotographic printer to be brought into close contact with the surface of the photoreceptor belt simultaneously with a printing operation, for removing contaminants containing untransferred toner of the photoreceptor belt, a transfer roller contamination removing means installed in the neighborhood of the transfer/fixation unit to be brought into close contact with the surface of the transfer roller simultaneously with a printing operation, for removing contaminants containing untransferred toner of the transfer roller, and a solvent supplying means for continuously supplying a solvent to the photoreceptor belt contamination removing means and the transfer roller contamination removing means so that the respective contamination removing means containing the solvent dissolve the untransferred toner to then be removed. 
     The photoreceptor belt contamination removing means may include a cleaning member assembly selectively brought into close contact with the surface of the photoreceptor belt, for wiping out the contaminants of the photoreceptor belt, a housing for supporting the cleaning member assembly, a means for making the cleaning member assembly closely contact and/or separate from the surface of the photoreceptor belt by moving the cleaning member assembly relative to the housing, and a frame fixed to the printer body, for detachably supporting the housing. 
     The transfer roller contamination removing means may include a cleaning member assembly selectively brought into close contact with the transfer roller, for wiping out the contaminants of the transfer roller, a frame fixed to a printer body and having each, for and supporting the cleaning member assembly, and a means for making the cleaning member assembly closely contact and/or separate from the transfer roller by moving the cleaning member assembly relative to the frame. 
     The solvent supplying means may include a solvent storage tank installed at one side of the printer body, for storing a solvent, and a solvent conveying member installed to be led from the solvent storage tank to be connected to the photoreceptor belt contamination removing means and the transfer roller contamination removing means, for continuously conveying the solvent stored in the solvent storage tank to the cleaning members of the respective contamination removing means. 
     As described above, in the liquid electrophotographic printer according to the present invention, simultaneously with printing, a cleaning member containing a solvent closely contacts a photoreceptor belt to thus continuously clean the photoreceptor belt, and another cleaning member containing a solvent cleans a transfer roller in close contact with the photoreceptor belt. Thus, the contamination of the photoreceptor belt and the transfer roller can be effectively removed even during a continuous printing process, thereby preventing deterioration of picture quality and print inferiority due to contamination of the photoreceptor belt and transfer roller, and obtaining a clean picture image. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above object and other advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings in which: 
     FIG. 1 is a schematic diagram illustrating major parts of a general liquid electrophotographic printer; 
     FIG. 2 is a schematic diagram illustrating major parts of a liquid electrophotographic printer employing a cleaning apparatus according to a preferred embodiment of the present invention; 
     FIG. 3 is an exploded perspective view illustrating the structure of a photoreceptor belt contamination removing means shown in FIG. 2; 
     FIG. 4 is a perspective view showing the assembled state of FIG. 3; 
     FIG. 5 is a plan view of FIG. 4; 
     FIG. 6 is a front view of FIG. 4; 
     FIG. 7 is a side view of FIG. 4; 
     FIG. 8 is a cross-sectional view taken along the line A—A of FIG. 5; 
     FIG. 9A is a cross-sectional view taken along the line B—B of FIG. 6, and FIG. 9B is a detailed diagram illustrating major parts shown in FIG. 9A; 
     FIG. 10 is a bottom view of FIG. 5; 
     FIG. 11 is an exploded perspective view illustrating the structure of a transfer roller contamination removing means shown in FIG. 2; and 
     FIG. 12 is a perspective view showing the assembled state of FIG.  11 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2 schematically illustrates major parts of a liquid electrophotographic printer  90  employing a cleaning apparatus according to a preferred embodiment of the present invention, FIGS. 3 through 10 illustrate a photoreceptor belt contamination removing means which is one of major parts of the present invention, and FIGS. 11 and 12 illustrate a transfer roller contamination removing means, respectively. In explaining the embodiment of the present invention, the same reference numerals are quoted for the same elements with the prior art in view of structure and function, a detailed explanation thereof will not be given, and only the characteristic parts of the present invention will be described in detail. In the drawings, reference numeral  10  denotes a photoreceptor belt,  20  an erasure unit,  30  a charging unit,  40  an exposure unit,  50  a development unit,  60  a drying unit,  70  a transfer/fixation unit, and  80  a printing sheet. Also, reference numeral  100  denotes a photoreceptor belt contamination removing means,  200  a transfer roller contamination removing means, and  300  a solvent supplying means, respectively. 
     As shown in FIG. 2, the photoreceptor belt  10  is wound around and supported by rollers  1 ,  2  and  3  installed in a printer body to and travels around a predetermined track. 
     The erasure unit  20 , the charging unit  30 , the exposure unit  40 , the development unit  50 , the drying unit  60  and the transfer/fixation unit  70  are installed in the neighborhood of the photoreceptor belt  10 . 
     The photoreceptor belt contamination removing means  100  is installed between the erasure unit  20  and the charging unit  30 , and serves to remove various contaminants containing untransferred toner which is not transferred to the transfer roller  71  during a transferring process and remains on the photoreceptor belt  10 . 
     The transfer roller contamination removing means  200  is installed next to the transfer roller  71  of the transfer/fixation unit  70 , and serves to remove various contaminants containing untransferred toner which is not transferred from the transfer roller  71  to the printing sheet  80  while selectively being in close contact with the transfer roller  71 . 
     The solvent supplying means  300  supplies a solvent to the photoreceptor belt contamination removing means  100  and the transfer roller contamination removing means  200  to allow the respective removing means  100  and  200  to contain the solvent to be used for dissolving and removing untransferred toner, thereby effectively removing various contaminants containing untransferred toner remaining on the photoreceptor belt  10  and the transfer roller  71 . In FIG. 2, reference numeral  101  denotes a backup roller. 
     Now, the construction of the aforementioned cleaning apparatus according to an embodiment of the present invention will be described in detail. 
     As shown in FIGS. 3 through 10, the photoreceptor belt contamination removing means  100  includes a cleaning member assembly  110  selectively brought into close contact with the surface of the photoreceptor belt  10 , a housing  130  for supporting the cleaning member assembly  110 , a means  150  for making the cleaning member assembly  110  closely contact and/or separate from the surface of the photoreceptor belt  10  by moving the cleaning member assembly  110  relative to the housing  130 , and a frame  170  fixed to the printer body, for detachably supporting the housing  130 . 
     The cleaning member assembly  110  includes a cleaning member  111 , a pair of fixing blocks  115  and  115 ′ coupled to both ends of the cleaning member  111 , and a bracket  119  integrally coupled to the pair of fixing blocks  115  and  115 ′. 
     The cleaning member  111  is formed by stacking a plurality of thin rectangular felts  113  on a fixing plate  112 . A cleaning sheet  114  (shown in FIG. 9) in direct contact with the photoreceptor belt  10  during a cleaning operation, is fixed to the bottom of the cleaning member  111 . Also, a pair of fixing pieces  112   a  and  112   b  each having a fixation hole are formed at both sides of the fixing plate  112 . 
     The fixing blocks  115  and  115 ′ have fixing parts  115   a  for fixing the fixing pieces  112   a  and  112   b , respectively. The cleaning member  111  is fixed to the fixing blocks  115  and  115 ′ by screws (not shown) engaged with the fixing holes of the fixing pieces  112   a  and  112   b  and the fixing holes of the fixing parts  115   a  to then be supported, in a state in which the fixing pieces  112   a  and  112   b  are placed in the fixing parts  115   a  of the fixing blocks  115  and  115 ′. Also, threaded holes  116  and  116 ′ piercing downward are formed on the fixing blocks  115  and  115 ′, respectively. Springs  120  and  120 ′ are inserted into the threaded holes  116  and  116 ′. The springs  120  and  120 ′ which elastically support the pair of fixing blocks  115  and  115 ′ downward with respect to the housing  130  to make the cleaning member  111  closely contact the surface of the photoreceptor belt  10  with a constant compressive force. Also, adjustment threads  121  and  121 ′ for supporting the springs  120  and  120 ′ inserted thereinto and adjusting the elasticity thereof, are upward engaged with the threaded holes  116  and  116 ′. Here, the upper portions of the springs  120  and  120 ′ are supported to the housing  130  and the lower portions thereof are supported to flanges  121   a  of the adjustment threads  121  and  121 ′. Thus, if the adjustment threads  121  and  121 ′ are rotated in forward and reverse directions, they advance and retreat to thus compress or expand the springs  120  and  120 ′ compared to the normal state, by which the compressive force applied to the photoreceptor belt  10  by the cleaning member  111  can be maintained at a constant level by adjusting the elasticity of the springs  120  and  120 ′. Also, the fixing blocks  115  and  115 ′ have a pair of openings  117  and  117 ′ facing each other at either side of the lower portions thereof, respectively, which will be described later. 
     The bracket  119  is configured to have a “⊂”-shaped section and is integrally fixed to the fixing blocks  115  and  115 ′ by a plurality of screws (not shown). To this end, a plurality of thread engagement holes  115   b  and  119   a  are formed at locations corresponding to the fixing blocks  115  and  115 ′ and the bracket  119 , respectively. Also, the bracket  119  has first throughholes  119   b  formed at locations corresponding to the threaded holes  116  and  116 ′ of the fixing blocks  115  and  115 ′ and second throughholes  119   c  formed in the neighborhood of the first throughholes  119   b . Here, the springs  120  and  120 ′ pierce first throughholes  19   b  of bracket  119  and pierce threaded holes  116  and  116 ′, respectively, of the fixing blocks  115  and  115 ′, and the second throughholes  119   c  are allowed to expose the fixing parts  115   a  of the fixing blocks  115  and  115 ′ to thus facilitate the screw engagement for fixing the cleaning member  111 . 
     The housing  130  has the shape of a box, the bottom of which is opened, and the cleaning member assembly is accommodated in the inner space thereof to then be supported. A pair of circular holes  131  are formed at both ends of the housing  130 , and a plurality of guiding slots  132  are formed on the rear surface of the housing  130  to be spaced a constant distance apart from each other. The circular holes  131  and guiding slots  132  will be described later. Guide rail  133  protrude outwardly along the one end of the housing  130 , and a plurality of throughholes  134  for exposing threads (not shown) for assembling the cleaning member  111  and the bracket  119  in the fixing blocks  115  and  115 ′, are formed on the top surface of the housing  130 . 
     The cleaning member contacting/separating means  150  includes a movement shaft  151  installed to be capable of moving axially through the openings  117  and  117 ′ formed on the fixing blocks  115  and  115 ′, a plurality of operating protrusions  152  protruding in the radial direction of the movement shaft  151 , and cam grooves  153  each having a predetermined inclined portion are formed on one side of the bracket  119 . Here, the movement shaft  151  is fitted into the circular holes  131  formed on the housing  130 , and a knob  154  is coupled to one end of the movement shaft  151 . The operating protrusions  152  pierce the cam grooves  153  of the bracket  119  to then be inserted in the guiding slots  132  of the housing  130 . If a knob  154  is moved, a moving shaft  151  is slid within guiding slots  132 . Thus, operating protrusions  152  is moved horizontally and then are in contact with cam grooves  153 . A housing  130  is not moved upward and downward but a bracket  119  is moved upward and downward due to the contact between the operating protrusions  152  and the cam grooves  153 . Engagement and disengagement of a cleaning member are performed manually by moving the knob  154 . 
     Therefore, if the knob  154  is pushed or pulled by hand, the movement shaft  151  moves axially. Here, the operating protrusions  152  fixed to the shaft  151  pierce the cam grooves  153  of the bracket  119  to then be inserted into the guiding slots  132  of the housing  130 , and the movement shaft  151  is inserted into the circular holes  131  of the housing  130 . Thus, as the movement shaft  151  moves, the positions of the operating protrusions  152  in the cam grooves  153  are changed so that the bracket  119  ascends or descends in the housing  130  according to the shapes of the cam grooves  153 . Here, since the fixing blocks  115  and  115 ′ are coupled to the bracket  119 , the cleaning member  111  eventually ascends or descends, so that the cleaning member  111  can closely contact or separate from the surface of the photoreceptor belt  10 . 
     The frame  170  has on its top surface fixing members  171  for fixing the frame  170  to a printer body, and a pair of facing slide grooves  173  formed at both sides of the interior part of the frame  170 , for allowing the guide rails  133  of the housing  130  to be inserted thereinto. In other words, the housing  130  can be easily fitted into or pulled out from the frame  170  in a slidable manner. 
     The transfer roller contamination removing means  200 , as shown in FIGS. 11 and 12, includes a cleaning member assembly  210  selectively brought into close contact with the transfer roller  71 , a frame  230  fixed to a printer body, for accommodating and supporting the cleaning member assembly  210 , and means  250  for making the cleaning member assembly  210  closely contact and/or separate from the transfer roller  71  by moving the cleaning member assembly  210  relative to the frame  230 . 
     The cleaning member assembly  210  includes a cleaning member  211 , a holder  213  for accommodating and supporting the cleaning member  211  and a holder bracket  215  integrally coupled to the holder  213 . 
     The cleaning member  211  is formed by stacking a plurality of thin rectangular felts  211   a  such that the heights of the respective felts  211   a  are made different to produce an arcuate lower profile corresponding to the outer circumferential surface of the transfer roller  71 . 
     The holder  213  is constructed such that a pair of vertical parts  213   b  extend from both sides of a horizontal part  213   a , and guiding protrusions  213   c  are formed on outer sides of the vertical parts  213   b . A fixing plate  214  is coupled on the front surface of the holder  213 . 
     The holder bracket  215  is substantially of a “┐” shape, and a pair of guide bars  216  and  216 ′ protrude at both sides of the horizontal part  215   a . Here, the vertical parts  215   b  of the holder bracket  215  are positioned on the rear surface of the holder  213  to support the cleaning member  211 . 
     The frame  230  has a plurality of latching holes  231  for fixing the same to the printer body, and a pair of first guiding holes  232  and  232 ′ on the top surface of the frame  230  at constant intervals. The guide bars  216  and  216 ′ of the holder bracket  215  are inserted into the first guiding holes  232  and  232 ′. Second guiding holes  233  and  233 ′ are formed inside the first guiding holes  232  and  232 ′, and elliptic guiding holes  234  are formed at either side thereof. Guiding protrusions  213   c  formed at either side of the holder  213  are inserted into the elliptic guiding holes  234 . 
     Also, the cleaning member contacting and separating means  250  includes a pair of movement bars  251  and  251 ′ piercing the second guiding holes  233  and  233 ′ to then be fixed to the holder bracket  215  at both ends thereof, springs  253  and  253 ′ interposed between the pair of movement bars  251  and  251 ′, for elastically supporting the holder bracket  215  downward with respect to the frame  230 , and a movement lever  255  movably installed to be capable of rotating relative to the movement bars  251  and  251 ′ upward protruding with respect to the frame  230  by means of a pin  257 . The movement lever  255  has an operation extension  255   a  having a predetermined height, at the lower portion thereof. Thus, if the movement lever  255  is rotated clockwise when viewed from FIG. 11, the holder bracket  215  is pushed by the distance corresponding to the height of the operation extension  255   a  due to the elasticity of the springs  253  and  253 ′, so that the cleaning member  211  is brought into close contact with the transfer roller  71 . If the movement lever  255  is rotated counterclockwise, it erects by pressing the operation extension  255   a  by means of the frame  230 . Here, since the frame  230  is fixed so as not to move, the holder bracket  215  installed in the frame  230  so as to move toward the guide bars  216  and  216 ′ is pulled toward the frame  230  by the distance corresponding to the height of the operation extension  255   a  of the movement lever  255 , so that the cleaning member  211  separate from the transfer roller  71 . 
     Also, a sheet guide  260  is installed in the frame  230 . The sheet guide  260  passes through between the transfer roller  71  and the fixation roller  72  to guide a sheet so as not to be fed between the cleaning member  211  and the transfer roller  71 . 
     The solvent supplying means  300  includes a solvent storage tank  310  installed at one side of the printer body, for storing a solvent, and a solvent conveying member  320  installed to be led from the solvent storage tank  310  to be connected to the photoreceptor belt contamination removing means  100  and the transfer roller contamination removing means  200 , for continuously conveying the solvent stored in the solvent storage tank  310  to the cleaning members  111  and  211  of the respective contamination removing means  100  and  200 . 
     Here, the solvent storage tank  310  may be constructed to supply the solvent to the cleaning members  111  and  211  of the respective contamination removing means  100  and  200  using a common tank. Otherwise, there may be two solvent storage tanks corresponding to the respective contamination removing means and. In the case of using a single solvent storage tank, two solvent conveying members are led from the solvent storage tanks to be connected to the respective contamination removing means  100  and  200 . Also, in the case of using two solvent storage tanks, the corresponding solvent storage tanks and the respective contamination removing means are mutually connected by means of the solvent conveying members. 
     The solvent conveying member  320  may be formed of felts, but is not restricted thereto. Also, the same liquid carrier as that contained in the developer liquid may be used as the solvent. 
     A printing process of a liquid electrophotographic printer employing the cleaning apparatus according to the present invention, will now be described. 
     The basic printing process is carried out in the similar manner to the printing process performed by the general liquid electrophotographic printer. 
     That is to say, the printing process is sequentially carried out by performing the following processing steps of: erasing the surface potential of the photoreceptor belt  10  simultaneously when a photoreceptor belt  10  rotates at a predetermined speed, if a printing instruction is input from an external data outputting device such as a computer; charging the photoreceptor belt to a predetermined potential; forming an electrostatic latent image on the charged photoreceptor belt; developing the electrostatic latent image; removing carrier components contained in the developed toner image; and transferring the toner image formed on the photoreceptor belt to a transfer roller to be printed on a printing sheet. 
     Here, during the transferring/fixing step, the toner image of the photoreceptor belt  10  is not completely transferred to the transfer roller  71  and remains on the photoreceptor belt  10  as contaminants, like in the conventional case. As described above, the untransferred toner remaining on the photoreceptor belt  10  is removed by the photoreceptor belt contamination removing means  100  according to the present invention having the cleaning member  111  closely contacting the photoreceptor belt  10  simultaneously with the printing operation. Also, the image transferred to the transfer roller  71  is completely transferred to the printing sheet  80  and remains on the transfer roller  70  as contaminants. The toner of the transfer roller  71  is removed by the transfer roller contamination removing means  200  installed in the neighborhood of the transfer/fixation roller  70 . 
     In other words, the cleaning member assembly  110  of the photoreceptor belt contamination removing means  100  descends simultaneously with the printing operation, so that the cleaning member  111  is pressed against the photoreceptor belt  10  with a constant pressure and various contaminants containing the untransferred toner of the photoreceptor belt  10  are continuously wiped out. In such a manner, the contaminants of the photoreceptor belt  10  can be removed. Here, since the solvent of the solvent storage tank  310  is continuously supplied to the cleaning member  111 , the cleaning member  111  closely contacts the surface of the photoreceptor belt  10  in a state in which it contains the solvent, and removes the contaminants of the photoreceptor belt  10 . Thus, the hardened toner on the photoreceptor belt  10  can be effectively removed while being dissolved. 
     Also, simultaneously with the operation of removing the contaminants of the photoreceptor belt, the cleaning member  211  of the transfer roller contamination removing means  200  is pressed against the transfer roller  71  with a constant pressure to continuously wipe out various contaminants containing untransferred toner of the transfer roller  71 . Thus, the contaminants of the transfer roller  71  can be removed. Also, since the solvent is continuously supplied from the solvent storage tank  310  to the cleaning member  211 , the toner of the transfer roller  71  can be effectively removed while being dissolved. 
     The above-described cleaning operation is continuously performed during printing. After printing, the respective cleaning members  111  and  211  are separated from the photoreceptor belt  10  and the transfer roller  71  by a predetermined distance. 
     As described above, the liquid electrophotographic printer according to the present invention performs printing while continuously removing various contaminants containing untransferred toner remaining on a photoreceptor belt and a transfer roller such that two cleaning members operate during printing. Thus, deterioration of picture quality and print inferiority, which are caused by contaminants containing untransferred toner remaining on the photoreceptor belt and the transfer roller, can be prevented, and a clean picture image can be obtained. 
     As described above, according to the present invention, various contaminants containing untransferred toner which is not transferred to a transfer roller during a transferring step and remains on a photoreceptor belt, are almost completely removed by a cleaning member closely contacting the photoreceptor belt before a charging step. Also, various contaminants containing untransferred toner which is not transferred from the transfer roller to a printing sheet and remains on the transfer roller, are removed by a cleaning member closely contacting the transfer roller. Thus, deterioration of picture quality and print inferiority, due to contamination of the photoreceptor belt and the transfer roller, can be prevented. 
     Also, the respective cleaning members according to the present invention contains a solvent supplied from a solvent storage tank and dissolves the contaminants in a state in which they closely contact a photoreceptor belt and a transfer roller, to then be wiped out, thereby effectively removing even hardened toner. 
     Also, according to the present invention, since a cleaning member closely contacting a photoreceptor belt, continuously cleans the photoreceptor belt simultaneously with a printing operation, a separate cleaning mode and the time required therefor are not necessary. Thus, the overall time required for printing can be reduced, and contamination of the photoreceptor belt can be avoided. 
     While a preferred embodiment of the invention has been shown and described, it will be appreciated by those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention and all such modifications are intended to be included within the scope of the following claims.