Abstract:
An image forming apparatus is provided with a casing, a drum unit including a photoconductive drum having a central axis extending in a first direction, and a charging device configured to charge the photoconductive drum, a fixing unit configured to fix an image on a printing medium, a fan configured to generate an air flow inside the casing, a filter configured to remove ozone included in the air, a first channel defined in the casing, the air directed from the fixing unit toward the fan flowing in the first channel, a second channel defined in the casing, the air directed from the charging device toward the fan flowing in the second channel, the filter being provided in the second channel, the second channel being arranged next to the first channel, and a blocking member configured to block communication between the first channel and the second channel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2013-123345 filed on Jun. 12, 2013. The entire subject matter of the Japanese application is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     Aspects of the present invention relate to an image forming apparatus employing an electrophotographic image forming method. 
     2. Prior Art 
     Conventionally, an image forming apparatus employing an electrophotographic image forming method has been known. Such an apparatus is generally configured such that a charged surface of a photoconductive drum is exposed to light which is modified based on image information to form an electrostatic latent image, toner is applied on the latent image to develop an image, the developed image is transferred on a recording sheet, and the transferred image is fixed by applying heat and pressure. 
     Such an apparatus has a fixing unit to fix the image on the sheet. The fixing unit typically has a heat roller and a pressure roller. The sheet on which the toner image has been transferred is caused to pass through a nip between the heat roller and the pressure roller, the heat and pressure are applied to the image, thereby the toner image is fixed on the sheet. 
     SUMMARY 
     The heat roller has a heating element inside the roller. Since a temperature of a surrounding area of the heat roller is raised, the image forming apparatus typically has a ventilation fan to ventilate the air inside the apparatus so that the temperature inside the apparatus does not increase excessively. 
     Such an image forming apparatus generally has a charging device which is used to charge the circumferential surface of the photoconductive drum. When the charging device is activated, ozone is generated. Therefore, the electrophotographic image forming apparatus generally has a filter to prevent the ozone from being discharged from the apparatus. 
     However, in the fixing unit, an airflow directed to the ventilation fan is generated, and the ozone generated at the charging device may be directed to the ventilation fan due to the air flow. In such a case, the air including the ozone does not pass through the filter, and thus the ozone may be discharged outside the apparatus. 
     In consideration of the above, aspects of the invention are advantageous in that an electrophotographic image forming apparatus is capable of removing ozone appropriately from the air discharged from the apparatus. 
     According to aspects of the invention, there is provided an image forming apparatus, which is provided with a casing, a drum unit including a photoconductive drum having a central axis extending in a first direction, and a charging device configured to charge the photoconductive drum, a fixing unit arranged adjacent to the drum unit and configured to fix an image on a printing medium, a fan configured to generate an air flow inside the casing, a filter configured to remove ozone included in the air passing therethrough, a first channel defined in the casing, the air directed from the fixing unit toward the fan flowing in the first channel, a second channel defined in the casing, the air directed from the charging device toward the fan flowing in the second channel, the filter being provided in the second channel, the second channel being arranged next to the first channel, and a blocking member configured to block communication between the first channel and the second channel. 
     With the above configuration, communication between the first channel and the second channel can be blocked by the blocking member. Therefore, joining of the air flowing in the first channel and the air flowing in the second channel can be well suppressed. Further, since the filter is provided in the second channel, the ozone can be removed from the air by simply causing the air to flow in the second channel. 
     According to aspects of the invention, there is provided an image forming apparatus, which is provided with a main body casing, a drum unit including a photoconductive drum having a central axis extending in a first direction, and a charging device configured to charge the photoconductive drum. Ozone may be generated when the charging device is activated. The image forming device further includes a fixing unit arranged adjacent to the drum unit and configured to fix an image on a printing medium. The fixing unit includes a heat generating member, a fan configured to generate an air flow inside the main body casing. The image forming apparatus further includes a filter configured to remove the ozone included in the air passing therethrough, a first channel defined in the main body casing, the air directed from the fixing unit toward the fan flowing in the first channel, the air flow in the first channel suppressing increase of temperature of the air around the fixing unit, a second channel defined in the main body casing, the air directed from the charging device toward the fan flowing in the second channel, the air including the ozone being caused to flow in the second channel, the filter being provided in the second channel, and a blocking member configured to block the air flowing in the second channel from entering the first channel. 
     According to aspects of the invention, there is provided an image forming apparatus, which has a plurality of drum units arranged at intervals in a predetermined direction. Each drum unit has a photoconductive drum having a central axis extending in a second direction perpendicular to the predetermined direction and a charging device configured to charge the photoconductive drum, the charging device having a charger frame. The image forming apparatus further includes a fixing unit configured to fix an image on a printing medium and arranged adjacent to the plurality of drum units in the predetermined direction, a main body casing accommodating the drum unit and the fixing unit therein and having an inner frame disposed between the drum unit and the fixing unit in the predetermined direction, and a flexible member having a first end portion and a second end portion opposite to the first end portion, the first end portion contact with the charger frame and the second end portion contact with the inner frame. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         FIG. 1  is a cross-sectional side view of a printer according to a first embodiment of the invention. 
         FIG. 2  is a perspective view showing a process unit, ventilation section and a second film of the printer shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional side view of a printer according to a second embodiment of the invention. 
         FIG. 4  is a cross-sectional side view of a printer according to a third embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     &lt;First Embodiment&gt; 
     A printer  1  according to a first embodiment of the invention is a horizontally-placed, direct tandem type color printer. 
     In the following description, when directions with respect to the printer are referred to, the directions for a user when the printer  1  is placed horizontally will be used. For example, in  FIG. 1 , the up and down directions of  FIG. 1  are the up-and-down directions of the printer  1 . Further, the front and rear directions of the printer  1  are a right-hand direction and a left-hand direction of  FIG. 1 , respectively. Right and left directions are indicated with reference to the directions when the printer  1  is viewed from its front side. Therefore, a direction perpendicular to a plane of  FIG. 1  is a right-and-left direction of the printer  1 . Specifically, a further direction with respect to the plane of  FIG. 1  is a left direction of the printer  1 , and a nearer side with respect to the plane of  FIG. 1  is a right direction of the printer  1 . 
     The printer  1  has a substantially box-like main body casing  2 , which has an opening  3 , a top cover  4 , a dividing wall  51  and an reinforcing member  52 . In the specification, the main body casing  2  will be simply referred to as the casing  2 . 
     The opening  3  is formed on an upper wall of the casing  2 . The top cover  4  is configured to be rotatable about an axis defined on its rear end, and configured to be located between a close position (indicated by solid lines in  FIG. 1 ) to close the opening  3  and an open position (indicated by phantom lines in  FIG. 1 ) at which the top cover  4  does not close the opening  3 . 
     A rear part of the top cover  4  is formed to have a substantial V-like recessed shape when viewed in the right-and-left direction. The V-like recessed part serves as a sheet discharge tray  32 . 
     The dividing wall  51  has a substantially planar plate shape, and extends in the right-and-left direction over the entire width of the casing  2  in the right-and-left direction. The dividing wall  51  is arranged below the sheet discharge tray  32 . The dividing wall  51  is arranged to extend in the up-and-down direction such that the dividing wall  51  divides a black process unit  6 K (described later) and a fixing unit  9  (described later). 
     The dividing wall  51  has a first auxiliary wall  95  and a second auxiliary wall  96 . The first auxiliary wall  95  is a substantially planar plate member extending in right-and-left direction corresponding to the entire width of the casing  2  in the right-and-left direction. The first auxiliary wall  95  extends from the dividing wall  51  and contacts the discharge tray  32 . The second auxiliary wall  96  is a planar plate member extending in the right-and-left direction corresponding to the entire width of the casing  2  in the right-and-left direction. Second auxiliary wall  96  extends from the dividing wall  51  and contacts a fixing frame  42  (described later). 
     The reinforcing member  52  is a substantially cylindrical shape. The reinforcing member  52  is arranged on a rear side with respect to the black process unit  6 K. Further, the reinforcing member  52  is arranged on a front side with respect to the dividing wall  51  with a space therebetween. The reinforcing member  52  is bridged between a right side and a left side of the casing  2  to reinforce the case. 
     The printer  1  has a sheet feeding unit  5 , a plurality of (four, according to the embodiments) process units  6 , a plurality of (four, according to the embodiments) LED units  7 , and the fixing unit  9  inside the casing  2 . 
     The sheet feeding unit  6  is arranged on a lower part of the casing  2 . The sheet feeding unit  5  has a sheet tray  30  configured to accommodate printing sheets, a pickup roller  10  arranged above the sheet tray  30 , and a pair of registration rollers  11  arranged above the pickup roller  10 . 
     As shown in  FIGS. 1 and 2 , the plurality of process units  6  are arranged at a central part, in the front-and-rear direction, inside the casing  2  spaced from each other. The plurality of process units  6  are configured to be detachably attached to the printer  1 . Specifically, the plurality of process units  6  are arranged such that upper end parts thereof are located below the top cover  4  (at the close position) and lower end parts thereof are located above a transferring unit  8  (described later). 
     The plurality of process units  6  correspond to colors of the toner, respectively. According to the embodiment, the colors of the toner are yellow, magenta, cyan and black, and the four process units  6  (i.e., a yellow process unit  6 Y, a magenta process unit  6 M, a cyan process unit  6 C and a black process unit  6 K) are arranged in this order from the front side to rear side. The plurality of process units  6  are configured to be detachable/attachable with respect to the casing  2  through the opening  3 . 
     Each of the plurality of process units  6  (i.e.,  6 Y,  6 M,  6 C and  6 K) has a drum cartridge  13  and a developing cartridge  14 . 
     In each of the process units  6 , the drum cartridge  13  has a drum frame  78 , a photoconductive drum  16 , a scorotron charger  17  and a cleaning roller  18 . 
     The drum frame  78  has a drum container  71  and a developing cartridge container  72 . 
     The drum container  71  has an upper front wall  77 , a upper rear wall  73 , a first film  85  and a pair of side walls  74 . 
     The upper front wall  77  is a planar plate member extending in the right-and-left direction, and arranged to incline to extend from an upper front position to a lower rear position when viewed in the right-and-left direction. 
     The upper rear wall  73  extends in the right-and-left direction, and is substantially U-shaped when viewed in the right-and-left direction such that the upper rear wall  73  surrounds the cleaning roller  18 . An upper end of the upper rear wall  73  is connected to a lower side of the upper front wall  77 . 
     The first film  85  is a flexible resin film and has a substantially rectangular shape extending in the right-and-left direction when viewed in the up-and-down direction. A front end part of the first film  85  is secured to a position between the upper front wall  77  and the upper rear wall  73 . A rear end part of the first film  85  is located at a lower front position with respect to the reinforcing member  52  with a space therebetween. The first film  85  is inclined such that the front end part is located at the lower front position and the rear end part is located at the rear upper position when viewed in the right-and-left direction. 
     One wall of the pair of side walls  74  is formed to extend in the front-and-rear direction and connected to right ends of the upper front wall  77  and the upper rear wall  73 . 
     The other wall of the pair of side walls  74  is formed to extend in the front-and-rear direction and connected to left ends of the upper front wall  77  and the upper rear wall  73 . 
     The developing cartridge container  72  has a pair of side walls  75  and a bottom wall  76 . 
     Rear ends of the pair of side walls  75  are connected to front ends of the pair of side walls  74 , respectively. Each of the pair of side walls  75  extends in the front-and-rear direction such that a portion closer to a front end thereof is located at an upper position. 
     The bottom wall  76  is connected to the lower ends of the pair of side walls  75  and bridged therebetween. 
     Each photoconductive drum  16  has a substantially cylindrical shape extending in the right-and-left direction. The photoconductive drum  16  is rotatably supported by the pair of side walls  74 , and a lower end part thereof is exposed outside from the drum container  71 . 
     The scorotron charger  17  is arranged at a rear above portion with respect to the photoconductive drum  16  with a space therebetween. The scorotron charger  17  extends in the right-and-left direction, and secured to the upper front wall  77 . 
     The cleaning roller  18  has a substantially cylindrical shape extending in the right-and-left direction, and rotatably supported by a pair of side walls  74 . The cleaning roller  18  is accommodated in a space defined by the upper rear wall  73  and the pair of side walls  74 . 
     The developing cartridge  14  is detachably accommodated in a space defined by a pair of side walls  75  and bottom wall  76  inside the developing cartridge unit  72 . 
     The developing cartridge  14  has a developing frame  20 , a developing roller  21 , a supplying roller  22  and a regulation blade  25 . 
     The developing frame  20  has a box-like shape extending in the right-and-left direction, and accommodates toner therein. 
     The developing roller  21  is rotatably supported at a lower end part of the developing frame  20 . A rear end part of the developing roller  21  is exposed to outside from the developing frame  20  and contacts the upper front part of the photoconductive drum  16 . 
     The supplying roller  22  is arranged at an upper front position with respect to the developing roller  21 . The supplying roller  22  is rotatably supported by the developing frame  20 , and a lower rear part of the supplying roller  22  contacts the upper front part of the developing roller  21 . 
     The regulation blade  25  contacts the rear end part of the developing roller  21 , and is configured to regulate a thickness of the toner supplied onto the circumferential surface of the developing roller  21 . 
     The plurality of LED units  7  are respectively arranged above the photoconductive drums  16  with spaces therebetween. 
     The transferring unit  8  is arranged below the plurality of process units  6 . The transferring unit  8  has a driving roller  26 , a driven roller  27 , a conveying belt  28  and a plurality of transferring rollers  29 . 
     The driving roller  26  is arranged below the photoconductive drum  16  of the black process unit  6 K. The driving roller  26  is rotatably supported by the casing  2 . 
     The driven roller  27  is arranged at a lower front position with respect to the photoconductive drum  16  of the yellow process unit  6 Y. The driven roller  27  is rotatably supported by the casing  2 . 
     The conveying belt  28  is arranged below the photoconductive drums  16  such that an upper part of the conveying belt  28  contacts each photoconductive drum  16 . The conveying belt  28  is an endless belt which is wound around the driving roller  26  and the driven roller  27 . As the driving roller  26  and the driven roller  27  rotates, the upper part of the conveying belt moves from the front side toward the rear side. 
     Each of the plurality of transferring rollers  29  is arranged below the corresponding one of the plurality of photoconductive drums  16  with the conveying belt  28  located therebetween. The plurality of transferring rollers  29  are rotatably supported by the casing  2 . Each of the plurality of transferring rollers  29  contacts the lower part of the conveying belt  28 . 
     The fixing unit  9  is arranged on the rear side of the black process unit  6 K and the transferring unit  8 . The fixing unit  9  has a heat roller  40 , a pressure roller  41  and the fixing frame  42 . 
     The heat roller  40  has a heating element (not shown) therein, and heats the printing sheet P with the heat generated by the heating element. 
     The pressure roller  41  is arranged on a lower rear position with respect to the heat roller  40 . An upper front part of the pressure roller  41  contacts a lower rear part of the heat roller  40 . 
     A relative position between the heat roller  40  and the pressure roller  41  is designed such that a line segment connecting a central axis of the heat roller  40  and the central axis of the pressure roller  41  is oriented in the same direction as a projecting direction from the fixing frame  42  to a duct  62 . 
     The fixing frame  42  rotatably supports the heat roller  40  and the pressure roller  41 . The fixing frame  42  has an upper cover  4  and a front cover  44 . 
     The upper cover  43  is arranged above the heat roller  40  with a certain space therebetween. The upper cover  43  extends in the right-and-left direction such that it covers the upper part of the heat roller  44 . Both right and left end parts of the upper cover  43  are fixed to the casing  2 . 
     The front cover  44  is arranged in front of the heat roller  40  with a space therebetween. The front cover  44  has a plate-like member extending in the right-and-left direction. The front cover  44  is secured to a front end part of the upper cover  43 . 
     Printing sheets P are accommodated in the tray  30 , and the tray  30  is arranged at a bottom part of the casing  2 . The printing sheets P are picked up one by one by the pickup roller  10  and conveyed such that the printing sheet P makes a U-turn. Further, the printing sheet P is conveyed toward an area between the photoconductive drums  16  and the conveying belt  28 . Then, by the conveying belt  28 , the printing sheet P is conveyed between the photoconductive drums  16  and the corresponding transferring rollers  29 , from the front side toward the rear side. 
     The toner inside the developing frame  20  is positively charged by frictional electrification between the supplying roller  22  and the developing roller  21 . The charged toner is supplied to the developing roller  21 . As the developing roller  21  rotates, the regulation blade  25  regulates the thickness of the toner on the circumferential surface of the developing roller  21 . As a result, the toner is carried on the circumferential surface of the developing roller  21  as a thin layer having a predetermined constant thickness. 
     As each photoconductive drum  16  rotates, the circumferential surface thereof is uniformly charged by a scorotron type charging device (hereinafter, referred to as a scorotron charger)  17 . Thereafter, the charged surface of each photoconductive drum  16  is exposed to light which is modulated in accordance with image data and emitted by the LED unit  7 . With this exposure operation, an electrostatic latent image corresponding to an image to be formed on the printing sheet P is formed on the circumferential surface of each photoconductive drum  16 . 
     The toner positively charged and borne on the circumferential surface of the developing roller  21  is supplied to the latent image formed on the circumferential surface of each photoconductive drum  16  as it rotates further. Then, due to a reversal phenomenon, a toner image corresponding to the latent image is formed on the circumferential surface of each photoconductive drum  16 . 
     Thereafter, when the printing sheet P passes through a portion between each photoconductive drum  16  and corresponding transferring roller  29 , the toner image on each photoconductive drum  16  is transferred onto the printing sheet P due to a transferring bias applied to each transferring roller  29 . The toner and/or paper particles residual on the circumferential surface of each photoconductive drum  16  are removed by the cleaning roller  18 . 
     Heat and pressure are applied to the toner image formed on the printing sheet P when the printing sheet P passes through a nip between the heat roller  40  and the pressure roller  41 , thereby the toner image is fixed on the printing sheet P. 
     Thereafter, the printing sheet P is conveyed such that it makes a U-turn as it proceeds upward, and discharged on the sheet discharge tray  32  formed on the top cover  4 . 
     The printer  1  has a ventilation unit  60  inside the casing  2 . The ventilation unit  60  is arranged, inside the casing  2 , at an upper position of the rear part of the sheet tray  30  and below the black process unit  6 K and the fixing unit  9 . The ventilation unit  60  has a duct  62 , a fan supporting frame  63 , a fan  61  and a filter  70 . 
     The duct  62  is arranged at a lower rear part with respect to the pressure roller  41 . The duct  62  has a box-like shape extending in the right-and-left direction, and a right end surface thereof is opened. The duct  62  has a plurality of ventilation holes  62   a  on its surrounding surface. 
     The fan supporting frame  63  is arranged on the right side with respect to the duct  62  and the driving roller  26 , and has an upper beam  91  and a lower beam  92 . 
     The upper beam  91  extends in the front-and-rear direction. A rear end part of the upper beam  91  is secured to the right end part of the duct  62 . 
     The lower beam  92  is arranged below the upper beam  91  and extends in the front-and-rear direction such that it extends in parallel with the upper beam  91 . 
     The fan  61  is secured to rear end parts of the upper beam  91  and the lower beam  92 . The fan  61  is arranged, inside the casing  2 , at a right side portion such that the fan  61  contacts the duct  62  in the right-and-left direction and is located next to the heat roller  40  in the up-and-down direction. The fan  61  is arranged at a lower rear position of or below a second film  80  and the fixing unit  9 , and relatively close to the fixing unit  9 . 
     The filter  70  is secured on the upper beam  91  such that the filter  70  is arranged on the right side with respect to the black process unit  6 K, and on the front side with respect to the fan  61 . The filter  70  has a plate-like member fixed to the upper beam  91  along the front-and-rear direction such that a thickness direction of the filter  70  is along the up-and-down direction and a surface direction thereof extends in the front-and-rear direction. The filter  70  is configured to allow the air to pass in its thickness direction. The filter  70  is configured such that, when the air containing ozone generated inside the casing  2  passes therethrough, the ozone is removed by the filter  70 . 
     The second film  80  is secured to the dividing wall  51 . The second film  80  is a flexible resin film having a rectangular shape extending in the right-and-left direction when viewed from the up-and-down direction. A rear part of the second film  80  is secured to a lower end part of the dividing wall  51 , and a front end part of the second film  80  elastically contacts the upper rear wall  73  of the drum container  71 . With this configuration, the second film  80  inclines such that the font end part is located at a lower front position, while the rear end part is located at an upper rear position, and bridged between the dividing wall  51  and the upper rear wall  73 . The second film  80 , together with the dividing wall  51 , divides a space on the black process unit  6 K, including the second channel S 2 , and a space on a rear side with respect to the black process unit  6 K, including the first channel S 1 . 
     A first channel S 1  is a projection space which is a space corresponding to a projection of the second film  80  and the fixing frame  42  onto the duct  62 . The first channel S 1  is defined by the dividing wall  51 , a second auxiliary dividing wall  96 , the fixing frame  42  and the rear end part of the driving roller  26 . 
     A second channel S 2  is a space defined by the second film  80 , the dividing wall  51 , the reinforcing member  52 , the first film  85  and the upper rear wall  73 . The second channel S 2  includes the filter  70  and a space inside the fan supporting frame  63 . The second channel S 2  is arranged next to the first channel via the second film  80 . 
     As above, the second film  80  blocks a communication between the first channel S 1  and the second channel S 2 . 
     When the fan  61  is actuated, an air flow occurs inside the casing  2 , and the air inside the casing is discharged outside the casing through a discharge opening (not shown). 
     At this stage, a first air flow F 1  directed from the fixing unit  9  toward the fan  61  is generated inside the first channel S 1 . Specifically, the high temperature air surrounding the heat roller  40  is caused to pass a portion around the pressure roller  41 , be directed to the duct  62 , and caused to enter the duct  62  via the plurality of ventilation holes  62   a . The air entering the duct  62  flows from left to right and reaches the fan  61 . 
     In the second channel S 2 , a second air flow F 2  directed from the scorotron charger  17  to the fan  61  is generated. Specifically, the ozone generated as the scorotron charger  17  operates, together with the air around the scorotron charger  17 , reaches the rear of the first film  85 . Thereafter, the air flows from left to right such that the air flows along the second film  80  and the upper rear wall  73 , and reaches a portion above the filter  70  which is located in a midway of the second channel S 2 . The air reaches the portion above the filter  70  and passes through the filter  70  along its thickness direction, flows inside the fan supporting frame  63  from front to rear therein, and reaches the fan  61 . 
     In each of the process units  6  other than the black process unit  6 K, a third air flow F 4  directed from the scorotron charger  17  to the fan  61  is generated. Specifically, the ozone generated as the scorotron charger  17  operates, together with the air around the scorotron charger  17 , flows to reach a portion in front of the adjacent process unit  6  located on the rear side. Then, the air flows from left to right, and then flows rearward and reaches a portion above the filter  70 . The air reaches the portion above the filter  70 . The third air flow F 4  and the second air flow F 2  join together, pass the filter  70  in the thickness direction, and reach the fan  61 . 
     As above, the ozone generated due to operation of the scorotron chargers  17  passes through the filter  70  together with the air, thereby the ozone is removed by the filter  70 . 
     Then, the first air flow F 1 , the second air flow F 2  and the third air flow F 4  directed to the fan  61  are discharged from the casing  2  as an air flow F 3 . 
     According to the first embodiment described above, the second film  80  is located between the first channel S 1  and the second channel S 2 . The second film  80  blocks communication between the first channel S 1  and the second channel S 2 . Therefore, it is possible to suppress that the first air flow F 1  and the second air flow F 2  join together. Further, the filter  70  is disposed in the midway of the second channel S 2 . Therefore, by simply introducing the ozone which is generated as the scorotron chargers  17  operate in the second channel S 2 , the ozone can be removed by the filter  70 . 
     As shown in  FIGS. 1 and 2 , the fan  61  is arranged at the right side portion inside the casing  2 . Further, the second channel S 2  is formed to extend in the right-and-left direction to incorporate a channel in which the air flows from the left side to the right side. Therefore, it is possible to form the second channel S 2  to extend along the upper front wall  77  and upper rear wall  73  of the drum container  71 . Therefore, according to the first embodiment, the second channel S 2  can be formed with a relatively simple structure. 
     As shown in  FIG. 2 , since the fan  61  and the filter  70  are arranged on the right side parts inside the casing  2 , the ozone generated due to operations of the scorotron chargers  17  is collected rightward with use of the fan  61  and removed by causing the ozone to pass through the filter  70 . Therefore, the ozone can be removed efficiently. 
     As shown in  FIGS. 1 and 2 , the second film  80  has an elongated rectangular shape extending in the right-and-left direction and is configured to be flexible. Therefore, it is possible to make the second film  80  elastically bend and contact the upper rear wall  73 . As a result, communication between the first channel S 1  and the second channel S 2  can be well blocked with the second film  80 . 
     As shown in  FIGS. 1 and 2 , the second film  80  is provided to the dividing wall  51 . Accordingly, it is possible to keep the second film  80  at a constant position. As a result, blocking of communication between the first channel S 1  and the second channel S 2  with the second film  80  is ensured, and joining of the first air flow F 1  and the second air flow F 2  can be well suppressed. 
     &lt;Modification of First Embodiment&gt; 
     According to the first embodiment, the second film  80  is secured to the dividing wall  51 . The invention needs not be limited to this configuration, and can be modified such that the second film  80  is secured to the upper rear wall  73 . Specifically, a front end part of the second film  80  may be secured to the upper rear wall  73  and a rear end part of the second film  80  may elastically contact a lower end part of the dividing wall  51 . 
     According to the above configuration, since the second film  80  is secured to the upper rear wall  73 , the second film  80  can be attached to the upper rear wall  73  when the black process unit  6 K is detached from the casing  2 . Thus, the second film  80  can be secured easily. 
     &lt;Second Embodiment&gt; 
     Hereinafter, a second embodiment of the invention will be described. It is noted that, in  FIG. 3 , members/elements similar to those referred to in the first embodiment are assigned with the same reference numbers and description thereof will not be repeated for brevity. 
     According to the first embodiment, the second film  80  is secured to the dividing wall  51 . According to the second embodiment, a third film  81  is secured to the reinforcing member  52  instead of the second film  80  of the first embodiment. 
     The third film  81  is a flexible resin film, and has a substantially rectangular shape extending in the right-and-left direction when viewed from the up-and-down direction. A rear end part of the third film  81  is secured to the rear end part of the reinforcing member  52 . A front end part of the third film  81  elastically contacts the upper rear wall  73  of the drum container  71 . With this configuration, the third film  81  is arranged to be inclined such that the front end is located at a lower front position while the rear end is located at an upper rear position, and bridged between the upper rear wall  73  and the reinforcing member  52 . 
     As above, according to the second embodiment, the second channel S 2  is defined by the third film  81 , the reinforcing member  52 , the first film  85  and the upper rear wall  73 . 
     The third film  81  blocks communication between the first channel  51  and the second channel S 2 . 
     According to the above configuration of the second embodiment, it is possible to locate the third film  81  at a constant position. As a result, blocking of the communication between the first channel S 1  and the second channel S 2  with use of the third film  81  is ensured, and joining of the first air flow F 1  and the second air flow F 2  can be well suppressed. 
     &lt;Modification of Second Embodiment&gt; 
     According to the second embodiment, the third film  81  is secured to the reinforcing member  52 . The invention needs not be limited to such a configuration, and can be modified in various ways. For example, the third film  81  may be secured to the upper rear wall  73  instead of the reinforcing member  52 . Specifically, as shown by dotted lines in  FIG. 3 , the lower end part of the third film  81  may be secured to the upper rear wall  73  and the upper end part of the third film  81  may elastically contact the front end part of the reinforcing member. 
     With the above configuration, since the third film  81  contacts the front end part of the reinforcing member  52 , the second channel S 2  can be appropriately defined. 
     &lt;Third Embodiment&gt; 
     Hereinafter, a third embodiment of the invention will be described. It is noted that, in  FIG. 4 , members/elements similar to those referred to in the foregoing description are assigned with the same reference numbers and description thereof will not be repeated for brevity. 
     According to the first embodiment, the rear end part of the second film  80  is secured to the dividing wall  51  and the front end part of the second film  80  elastically contacts the upper rear wall  73 . According to a third embodiment, as shown in  FIG. 4 , a front end of a fourth film  82  is secured to the upper rear wall  73  and a rear end part of the fourth film  82  contacts the fixing frame  42 , instead of employing the second film  80 . 
     According to the third embodiment, the fixing frame  42  has a protruding plate  45 . The protruding plate  45  is a plate-like member extending in the right-and-left direction. The protruding plate  45  protrudes frontward from a front end of the upper cover  43 , and a front end part of the protruding plate  45  is located on a rear side of the upper rear wall  73  with a space therebetween. 
     The fourth film  82  is a flexible resin film and a substantially rectangular shape extending in the right-and-left direction when viewed from the up-and-down direction. A front end part of the fourth film  82  is secured to the upper rear wall  73 , while a rear end part of the fourth film  82  elastically contacts the front end part of the protruding plate  45 . With this configuration, the fourth film  82  inclines such that a front end part thereof is located at a lower front position while a rear end part is located at an upper rear position so that the fourth film  82  is bridged between the upper rear wall  73  and the protruding plate  45 . 
     According to the third embodiment, the second channel S 2  is defined by the fourth film  82 , the fixing frame  42 , the second auxiliary dividing wall  96 , the dividing wall  51 , the reinforcing member  52 , the first film  85  and the upper rear wall  73 . 
     As above, the fourth film  82  blocks communication between the first channel S 1  and the second channel S 2 . 
     According to the above configuration, since the fourth film  82  contacts the fixing frame  42 , the first channel S 1  and the fixing frame  42  can be defined in an integrated manner. 
     &lt;Modification of Third Embodiment&gt; 
     According to the third embodiment, the fourth film  82  is secured to the upper rear wall  73 . The invention needs to be limited to such a configuration, but can be modified in various ways. For example, the fourth film  82  may be secured to the protruding plate  45 . Specifically, the rear end part of the fourth film  82  may be secured to a rear end part of the protruding plate  45 , while the front end part of the fourth film  82  may elastically contact the upper rear wall  73 . 
     According to the above configuration, similar to the first embodiment, the fourth film  82  can be located at a constant position. As a result, blocking of communication between the first channel S 1  and the second channel S 2  can be ensured and joining of the first air flow F 1  and the second air flow F 2  can be well suppressed.