Abstract:
An ozone purification unit of an electrographic image forming apparatus oxidizes and removes ozone using a catalyst filter. The ozone is carried by a carrier vapor generated in the wet-type electrophotographic image forming apparatus. The ozone purification unit of the wet-type electrophotographic image forming apparatus has a holder member that forms inner and outer paths in a sealing member to partition an engine part of the image forming apparatus and to support the catalyst filter. A fan is disposed at an exit of the holder member to draw in the carrier vapor into the catalyst filter. A heater is disposed at an entrance of the holder member and around the catalyst filter to heat the drawn-in carrier vapor and to prevent the carrier vapor from being deposited on the catalyst filter. A cooling device cools the carrier vapor from which the ozone is removed after passing through the catalyst filter and the heater.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 2004-32938, filed May 11, 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 electrophotographic image forming apparatus. More particularly, the present invention relates to an ozone purification unit for removing ozone (O 3 ) contained in a chemical compound, and a wet-type electrophotograhic image forming apparatus having the same.  
         [0004]     2. Description of the Related Art  
         [0005]     Generally, a wet-type electrophotographic image forming apparatus, such as a printer or a multi-function office machine, scans a laser beam onto a photoconductive medium, such as a photoconductive belt or drum, to form an electrostatic latent image. A visible image formed by attaching a developer onto the electrostatic latent image is transferred, thereby implementing a desired image.  
         [0006]      FIG. 1  illustrates an example of a wet-type electrophotographic image forming apparatus. The wet-type electrophotographic image forming apparatus has a plurality of electrifying units  131 ,  132 ,  133  and  134  for forming an electrostatic latent image respectively on a plurality of photoconductive drums  121 ,  122 ,  123  and  124  provided in a main body  110 . A plurality of laser scanning units  141 ,  142 ,  143  and  144 , and a plurality of developing units  151 ,  152 ,  153  and  154  apply a developer on the electrostatic latent imageto develop the image. A plurality of first transfer rollers  171 ,  172 ,  173  and  174  and a second transfer roller  180  transfer the developed image onto a printing medium P. A fusing unit  190  fuses the image transferred on the printing medium P by heat and pressure. An oxidant unit  195  purifies a carrier vapor generated during the printing process.  
         [0007]     In using the above-described wet-type electrophotographic image forming apparatus  100 , the carrier vapor generated in the developing units  151 ,  152 ,  153  and  154  and the fusing unit  190  is mixed with ozone (O 3 ) generated by electric discharge of the electrifying units  131 ,  132 ,  133  and  134 .  
         [0008]     In the conventional wet-type electrophotographic image forming apparatus  100 , the oxidant unit  195  purifies the carrier vapor. However, in order to totally purify the carrier vapor generated in the wet-type electrophotographic image forming apparatus  100 , a mass of the oxidant units needs to be provided, which is expensive.  
         [0009]     More specifically, although a carrier vapor C in a sealing member  198  of the conventional wet-type electrophotographic image forming apparatus  100  is in very low concentration, the carrier vapor C containing ozone is drawn into the oxidant unit  195  in a direction indicated by arrow A of  FIG. 1  through a suction path  196 , such that the ozone included in the carrier vapor C is removed.  
         [0010]     The drawn-in carrier vapor C containing the ozone is mixed with a carrier vapor B of high concentration that is generated in the fusing unit  190 .  
         [0011]     Since the oxidant reacts at a high temperature, ozone is thermally oxidized in the oxidant unit  195 .  
         [0012]     Therefore, the oxidant unit  195  has to process a relatively large amount of the carrier vapor B+C compared to when processing only the high-concentration carrier vapor B.  
         [0013]     Thus, to react the oxidant in the oxidant unit  195  with the large amount of carrier vapor B+C, the oxidant needs to be applied over a wide area.  
         [0014]     As a result, a large quantity of the oxidant is required, thereby increasing manufacturing costs.  
         [0015]     There is a well-known general method for removing ozone, which uses a catalyst capable of oxidizing ozone at a normal temperature. However, the carrier vapor is condensed and deposited on a surface of the catalyst in the wet-type electrophotographic image forming apparatus  100 , and this deteriorates performance and lifespan of the catalyst. Therefore, the general method is not suitable for the wet-type electrophotographic image forming apparatus  100 .  
       SUMMARY OF THE INVENTION  
       [0016]     Accordingly, an aspect of the present invention is to provide an ozone (O 3 ) purification unit for collecting ozone included in a carrier vapor generated in a wet-type electrophotographic image forming apparatus by a catalyst filter and removing the ozone in an effective and economical way, and a wet-type electrophotographic image forming apparatus having the same.  
         [0017]     Another aspect of the present invention is to provide a wet-type electrophotographic image forming apparatus for economically removing a carrier vapor generated during an image forming process using a small amount of oxidant.  
         [0018]     Still another aspect of the present invention is to provide an ozone purification unitdisposed in a system, such as a device that generates a compound gas containing ozone, to collect the ozone by a catalyst filter, thereby removing the ozone effectively and economically.  
         [0019]     An ozone purification unit is disposed in a system that generates a compound gas comprising ozone to oxidize and remove the ozone using a catalyst filter. The ozone purification unit has a holder member for supporting the catalyst filter. A guide fan draws in and guides the compound gas to help the compound gas pass through the catalyst filter. A heating device heats the compound gas to prevent deposition of the compound gas onto the catalyst filter.  
         [0020]     The heating device has a plurality of unit heaters mounted on a front of the catalyst filter.  
         [0021]     The plurality of unit filters are structured in a web or a honeycomb form.  
         [0022]     The heating device further includes a band heater surrounding the catalyst filter.  
         [0023]     The ozone purification unit further includes an adiabatic member surrounding the band heater.  
         [0024]     The ozone purification unit further includes a cooling device for cooling heat generated from the compound gas that passes through the catalyst filter.  
         [0025]     A wet-type electrophotographic image forming apparatus includes an electrifying unit for forming an electrostatic latent image on a photoconductive medium. A developing unit applies a developer to the photoconductive medium. A transfer, unit transfers the developer developed on the photoconductive medium to a paper. A fusing unit fixes the developer onto the paper. An oxidant unit oxidizes a carrier vapor generated in the fusing unit. An ozone purification unit oxidizes and removes ozone generated in the electrifying unit using a catalyst filter.  
         [0026]     The ozone purification unit includes a holder member for supporting the catalyst filter. A guide fan draws in and guides the compound gas to help the compound gas pass through the catalyst filter. A heating device heats the compound gas to prevent deposition of the compound gas onto the catalyst filter.  
         [0027]     The heating device includes a plurality of unit heaters mounted on a front of the catalyst filter.  
         [0028]     The plurality of unit filters are structured in a web or a honeycomb form.  
         [0029]     The heating device further includes a band heater surrounding the catalyst filter.  
         [0030]     The wet-type electrophotographic image forming apparatus further includes an adiabatic member surrounding the band heater.  
         [0031]     The wet-type electrophotographic image forming apparatus further includes a cooling device for cooling heat generated from the compound gas that passed through the catalyst filter.  
         [0032]     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 DRAWING FIGURES  
       [0033]     The above aspect and other features of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawing figures, wherein;  
         [0034]      FIG. 1  is a schematic view of a conventional wet-type electrophotographic image forming apparatus;  
         [0035]      FIG. 2  is a schematic view of a wet-type electrophotographic image forming apparatus according to an embodiment of the present invention;  
         [0036]      FIG. 3  is a schematic view of an ozone purification unit of  FIG. 2 ;  
         [0037]      FIGS. 4A and 4B  are perspective views of a unit heater of the ozone purification unit of  FIG. 3 ;  
         [0038]      FIG. 5  is a perspective view of the mutual operation of a catalyst filter, a band heater and an adiabatic member of  FIG. 3 ; and  
         [0039]      FIG. 6  is a perspective view of a cooling member of  FIG. 3 . 
     
    
       [0040]     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.  
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0041]     Hereinafter, an oxidant unit and a wet-type electrophotographic image forming apparatus having the same according to exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawing figures.  
         [0042]     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 elements and constructions are not described in detail for conciseness and clarity.  
         [0043]      FIG. 2  schematically illustrates a wet-type electrophotographic image forming apparatus according to an exemplary embodiment of the present invention.  
         [0044]     Referring to  FIG. 2 , the wet-type electrophotographic image forming apparatus  200  includes a plurality of laser scanning units  211 ,  212 ,  213  and  214 ; a plurality of photoconductive drums  221 ,  222 ,  223  and  224 ; a plurality of electrifying units  226 ,  227 ,  228  and  229 ; a plurality of developing units  231 ,  232 ,  233  and  234 ; a transfer unit  240 ; a fusing unit  250 ; an oxidant unit  260 ; and an ozone purification unit  270 .  
         [0045]     The plurality of laser scanning units  211 ,  212 ,  213  and  214  scan a laser beam onto surfaces of the plurality of photoconductive drums  221 ,  222 ,  223  and  224  that are electrified with a certain electric potential by the electrifying units  226 ,  227 ,  228  and  229 .  
         [0046]     Surfaces of the photoconductive drums  221 ,  222 ,  223  and  224  are coated with a photoconductive sensitization layer. A difference in the electric potentials is caused on the surfaces of the photoconductive drums  221 ,  222 ,  223  and  224  scanned with the laser beam, thereby forming an electrostatic latent image.  
         [0047]     The developing units  231 ,  232 ,  233  and  234  supply the developer respectively to the photoconductive drums  221 ,  222 ,  223  and  224 . The developing units  231 ,  232 ,  233  and  234  respectively store developers of different colors, such as yellow, magenta, cyan and black. Upon formation of the electrostatic latent image on the photoconductive drums  221 ,  222 ,  223  and  224 , the developing units  231 ,  232 ,  233  and  234  transfer the respective color developers onto the photoconductive drums  221 ,  222 ,  223  and  224 .  
         [0048]     Accordingly, visible images are formed by the developers on the surfaces of the respective photoconductive drums  221 ,  222 ,  223  and  224 . The developers consist of a toner for developing the electrostatic latent image and a liquid carrier for facilitating movement of the toner.  
         [0049]     The transfer unit  240  transfers the visible images formed on the photoconductive drums  221 ,  222 ,  223  and  224  onto a paper. The transfer unit  240  comprises a transfer belt  241 , first transfer rollers  242 ,  243 ,  244  and  245 , and a second transfer roller  246 . As shown in  FIG. 2 , the transfer belt  241  receives the visible images while running in contact with the surfaces of the photoconductive drums  221 ,  222 ,  223  and  224 .  
         [0050]     The respective first transfer rollers  242 ,  243 ,  244  and  245  are mounted to correspond to the photoconductive drums  221 ,  222 ,  223  and  224  to transfer the visible images formed on the photoconductive drums  221 ,  222 ,  223  and  224  onto the transfer belt  241 . The developers of different colors, such as yellow, magenta, cyan and black, are overlapped with one another on the transfer belt  241 , thereby forming a color image.  
         [0051]     The second transfer roller  246  transfers the color image formed on the transfer belt  241  onto a paper.  
         [0052]     The fusing unit  250  applies heat and pressure to the paper to fix the color image formed on the transfer belt  241  onto the paper. During the heat and pressure application period, the liquid carrier of developer components is vaporized, thereby generating a carrier vapor G  
         [0053]     The oxidant unit  260  purifies the carrier vapor G generated in the fusing unit  250 .  
         [0054]     The ozone purification unit  270  thermally oxidizes ozone (O 3 ) generated by electric discharge from the electrifying units  226 ,  227 ,  228  and  229 .  
         [0055]     The high temperature carrier vapor G generated in the fusing unit  250  is purified by the oxidant unit  260 , and ozone included in the low-concentration carrier vapor D generated in the developing units  231 ,  232 ,  233  and  234  is removed by the ozone purification unit  270 . Accordingly, a very small amount of oxidant is required.  
         [0056]      FIG. 3  is a schematic view of the ozone purification unit  270  of  FIG. 2 . The ozone purification unit  270  includes a holder member  337 , a guide fan  335 , heating devices  301 ,  305  and  307 , and a cooling device  350 .  
         [0057]     The holder member  337  forms inner and outer paths in a sealing member  298  ( FIG. 2 ), thereby partitioning an engine part of the wet-type electrophotographic image forming apparatus  200  ( FIG. 2 ), and supports the guide fan  335  and the heating devices  301 ,  305  and  307 .  
         [0058]     The guide fan  335  draws in and induces the low-concentration carrier vapor D containing the ozone toward a catalyst filter  331 .  
         [0059]     The heating device  305  includes a plurality of unit heaters  301  disposed in front of the catalyst filter  331 , a band heater  305  enclosing the catalyst filter  331 , and an adiabatic member  307  enclosing the band heater  305 . With this arrangement, the heating device  305  prevents deterioration of performance and lifespan of the catalyst filter  331  caused by the low-concentration carrier vapor D drawn through the catalyst filter  331 .  
         [0060]     The cooling device  350  is disposed behind the guide fan  335  to remove heat inside the wet-type electrophotographic image forming apparatus  200  ( FIG. 2 ) for the normal operation of the whole apparatus.  
         [0061]     The cooling device  350  includes a cooling plate  351   b  to remove heat from the low-concentration carrier vapor D that is heated while passing through the unit heater  301  and the band heater  305 . The cooling device  350  also includes a front cooling fin  351   a  and a rear cooling fin  351   c  projected from a front surface and a back surface of the cooling plate  351   b , respectively.  
         [0062]     A rear cooling fan  355  is further provided externally of a casing  352  of the wet-type electrophotographic image forming apparatus  200  ( FIG. 2 ) to enhance cooling efficiency.  
         [0063]     With the above structure, the ozone included in the unit heater  301  flows in a direction indicated by arrow E, thereby being primarily heated by the unit heater  301 .  
         [0064]     The ozone in the heated low-concentration carrier vapor D is oxidized while passing through the catalyst filter  331 . The band heater  305  reheats the low-concentration carrier vapor D surrounding the catalyst filter  331  to prevent a liquid carrier, which is generated from the cooling of low-concentration carrier vapor D, from attaching to the catalyst filter  331  while the ozone is oxidized.  
         [0065]     An ozone-removed carrier vapor X drains to the outside of the sealing member  298  ( FIG. 2 ) in the direction indicated by arrow E by the guide fan  335  mounted in the holder member  337 .  
         [0066]     The heat of the ozone-removed carrier vapor X that drains out of the sealing member  298  ( FIG. 2 ) collides with the cooling fin  351   a  projected on the front surface of the cooling plate  351   b  and is discharged outwardly therefrom.  
         [0067]     Some of the heat in the ozone-removed carrier vapor X is transmitted through the cooling plate  351   b , and the transmitted heat is drained out of the wet-type electrophotographic image forming apparatus  200  ( FIG. 2 ) through a rear side of the cooling plate  351   b  and the rear cooling fin  351   c.    
         [0068]     The rear cooling fan  355  continuously or intermittently drives for quick removal of the heat, and draws in external cool air Y ( FIG. 3 ) in a direction indicated by arrow F, such that the cool air Y collides with the rear side of the cooling plate  351   b  and the rear cooling fin  351   c.    
         [0069]      FIGS. 4A and 4B  are perspective views showing the unit heater of the oxidant unit of  FIG. 3 . Referring to  FIG. 4A , the unit heater  301  is disposed within a supporter wall  302  surrounding the unit heater  301  and supplying power to the unit heater  301 .  
         [0070]     The unit heater  301  applies heat to the low-concentration carrier vapor D to prevent the liquid carrier from being attached on the catalyst filter  331  when the liquid carrier is generated from the cooling of the low-concentration carrier vapor D.  
         [0071]     A length interval I and a width interval J of the unit heater  301  are narrowly formed for a dense texture of the unit heater  301  such that a lot of heat is transmitted to the low-concentration carrier vapor D in a short time.  
         [0072]     As shown in  FIG. 4B , the unit heater  301  may be formed in any suitable manner, such as the shown honeycomb pattern. In addition to the web and the honeycomb patterns of  FIGS. 4A and 4B , the unit heater  301  may have other various forms for transmission of heat to the low-concentration carrier vapor D.  
         [0073]      FIG. 5  is a perspective view showing the relationship in operation among the catalyst filter  331 , the band heater  305  and the adiabatic member  307 . Referring to  FIG. 5 , the band heater  305  encloses the catalyst filter  331  and reheats the low-concentration carrier vapor D to prevent the low-concentration carrier vapor D heated by the unit heater  301  ( FIG. 4A ) from being condensed by reaction with the catalyst filter  331 .  
         [0074]     The band heater  305  may apply the heat to the catalyst filter  331  constantly or intermittently according to an amount of the low-concentration carrier vapor D.  
         [0075]     The adiabatic member  307  encloses the band heater  305  to prevent heat leakage from the band heater  305 .  
         [0076]     For adiabatic efficiency, a fibroid material formed of a ceramic fiber is preferably used for the adiabatic member  307 .  
         [0077]     With this arrangement, the low-concentration carrier vapor D becomes the ozone-removed carrier vapor X after reacting with the catalyst filter  331 , and is discharged out of the catalyst filter  331  in the direction indicated by arrow E.  
         [0078]      FIG. 6  is a perspective view showing the cooling device of  FIG. 3 . Referring to  FIG. 6 , the cooling plate  351   b  removes heat from the ozone-removed carrier vapor X and transmits the heat externally of the wet-type electrophotographic image forming apparatus  200  ( FIG. 2 ).  
         [0079]     The front cooling fin  351   a  and the rear cooling fin  351   c  are projected from the cooling plate  351   b  to increase a cooling surface area. For a more dense texture, a length interval P and a width interval R are formed preferably narrowly.  
         [0080]     The number of the rear cooling fins  351   c  is greater than that of the front cooling fins  351   a  so that the cool air Y exiting the wet-type electrophotographic image forming apparatus  200  ( FIG. 2 ) widely contacts the rear cooling fin  351   c.    
         [0081]     The cooling plate  351   b , the front cooling fin  351   a  and the rear cooling fin  351   c  may be formed of metal, such as copper and aluminum for higher thermal conductivity.  
         [0082]     With the above structure, a heat Q included in the ozone-removed carrier vapor X is transmitted in the direction indicated by arrow E and removed upon colliding with the front cooling fin  351   a  and the cooling plate  351   b . Also, some of the heat Q is passed through the cooling plate  351   b  and removed by the cool air Y colliding with the rear cooling fin  351   c  and the rear side of the cooling plate  351   b . Accordingly, the inside of the wet-type electrophotographic image forming apparatus  200  ( FIG. 2 ) is maintained at a proper temperature, thereby enabling the normal operation of the wet-type electrophotographic image forming apparatus  200  ( FIG. 2 ).  
         [0083]     As can be appreciated from the above description of the ozone purification unit  270  and the wet-type electrophotographic image forming apparatus  200  having the same, according to exemplary embodiments of the present invention, an inner temperature of the apparatus does not increase, and ozone is thermally oxidized by a dedicated ozone purification unit  270 . Therefore, use of an oxidant may be reduced, thereby saving expenses.  
         [0084]     Further, even in a system, such as a device that generates a compound gas, performance and lifespan of the catalyst are not deteriorated.  
         [0085]     While the invention has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.