Patent Publication Number: US-9429878-B2

Title: Image forming apparatus including a toner conveyance portion with vent holes having filters disposed thereon

Description:
INCORPORATION BY REFERENCE 
     This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2014-153191 filed on Jul. 28, 2014, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to an electrophotographic image forming apparatus that performs an image formation with use of toner. 
     In an image forming apparatus, generally, an electrostatic latent image formed on an image carrier such as a photoconductor drum is visualized by developer in a developing device, and the visualized image is transferred to a recording medium. At this time, some toner may not be transferred to the recording medium and remain on the surface of the photoconductor drum. The remnant toner is removed from the surface of the photoconductor drum by a cleaning device, and is collected, as waste toner, in a waste toner collection container. The waste toner is conveyed to a predetermined position by a screw in the horizontal direction parallel to the photoconductor drum. A conveyance duct is disposed at the predetermined position, and the waste toner is introduced into the conveyance duct and conveyed by another screw in the conveyance duct to the waste toner collection container. 
     Meanwhile, toner is likely to be scattered in the developing device. As a result, when an air pressure inside the developing device is higher than an air pressure outside thereof, tonner scattered inside the developing device may leak to the outside. When toner leaks to outside of the developing device, inside and outside of the image forming apparatus may be contaminated by the toner. To prevent this, conventionally, a suction nozzle is provided in the vicinity of the developing device such that scattered toner is sucked by a fan and trapped by a filter, thereby restricting the toner from being scattered in the peripheral of the developing device. 
     SUMMARY 
     An image forming apparatus according to an aspect of the present disclosure includes a toner conveyance portion, a vent hole portion, an air suction portion, and a filter portion. The toner conveyance portion forms a toner conveyance passage between a developing device and a collection container such that toner discharged from the developing device is conveyed in the toner conveyance passage and collected in the collection container. The vent hole portion is formed in the toner conveyance portion and allows inside and outside of the toner conveyance portion to communicate with each other such that air can be ventilated between the inside and the outside of the toner conveyance portion. The air suction portion is configured to suck the air inside the toner conveyance portion via the vent hole portion. The filter portion is disposed on the vent hole portion and configured to trap toner contained in the air sucked by the air suction portion. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description with reference where appropriate to the accompanying drawings. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an outer appearance view of an image forming apparatus according to an embodiment of the present disclosure.  FIG. 1B  is a schematic diagram showing the internal configuration of the image forming apparatus. 
         FIG. 2  is a schematic diagram showing the configuration of an image forming portion of the image forming apparatus. 
         FIG. 3  is a diagram for explaining flow paths respectively provided in the image forming portions, wherein toner and the like removed from photoconductor drums by cleaning members flow in the flow paths until they are collected in a collection container. 
         FIG. 4  is a diagram showing the internal configuration of a storage portion. 
         FIG. 5  is an outer appearance perspective view of the storage portion. 
         FIG. 6  is an enlarged cross-sectional view of a vent hole portion. 
         FIG. 7  is a diagram showing how air flows when a fan is operated. 
         FIG. 8  is a diagram showing an idea of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following describes an embodiment of the present disclosure with reference to the drawings. It should be noted that the following description is an example of a specific embodiment of the present disclosure and should not limit the technical scope of the disclosure. 
       FIG. 1A  is an outer appearance perspective view showing the configuration of an image forming apparatus  1  which is an embodiment of an image forming apparatus of the present disclosure. It is noted that the following description is given with use of an up-down direction D 1 , a front-rear direction D 2 , and a left-right direction D 3  that are defined in  FIG. 1A  based on the normal use state of the image forming apparatus  1 . 
     As shown in  FIG. 1A , the image forming apparatus  1  is a printer. The image forming apparatus  1  prints an input image to a print sheet by using a print material such as toner. It is noted that the image forming apparatus  1  is not limited to a printer. Other examples of the image forming apparatus of the present disclosure include a facsimile, a copier, and a multifunction peripheral that has the functions of these. 
     The image forming apparatus  1  prints an image to a print sheet based on image data input from an external source via a network communication portion (not shown). As shown in  FIG. 1A , the image forming apparatus  1  includes a housing  2  that includes a cover of an outer frame, and an inner frame. 
     As shown in  FIG. 1B , the image forming apparatus  1  is a so-called tandem color image forming apparatus and includes a plurality of image forming portions  3 , an intermediate transfer unit  4 , a secondary transfer device  5 , a fixing device  6 , an exposure device  7 , a sheet feed portion  8 , a sheet discharge portion  9 , and a control portion  10 . 
     The plurality of image forming portions  3  are arranged in alignment in the front-rear direction D 2 . The plurality of image forming portions  3  respectively form toner images of different colors. In  FIG. 1B , an image forming portion  3  positioned on the most rear side forms a toner image by black toner, an image forming portion  3  positioned in front of it forms a toner image by yellow toner, an image forming portion  3  positioned in front of it forms a toner image by cyan toner, and an image forming portion  3  positioned on the most front side forms a toner image by magenta toner. Each of the image forming portions  3  includes a photoconductor drum  11 , a charging device  12 , a developing portion  13  (an example of the developing device of the present disclosure), a primary transfer device  14 , and a cleaning portion  15 . As a result, the image forming apparatus  1  includes a plurality of developing portions  13 . 
     The intermediate transfer unit  4  includes an intermediate transfer belt  4 A, a driving roller  4 B, and a driven roller  4 C. Supported by the driving roller  4 B and the driven roller  4 C so as to be rotationally driven, the intermediate transfer belt  4 A can move (run) in the state where its surface is in contact with the surfaces of the photoconductor drums  11 . When the intermediate transfer belt  4 A passes through between the photoconductor drums  11  and the primary transfer devices  14 , the toner images are transferred in sequence from the photoconductor drums  11  to a surface of the intermediate transfer belt  4 A in such a way as to be overlaid with each other. 
     The secondary transfer device  5  transfers the toner image transferred on the intermediate transfer belt  4 A, to a print sheet that is conveyed from the sheet feed portion  8 . The print sheet with the toner image transferred thereon is conveyed to the fixing device  6 . The fixing device  6  includes a heating roller  6 A and a pressure roller  6 B. 
       FIG. 2  is a cross-sectional view schematically showing the photoconductor drum  11 , the developing portion  13 , and the cleaning portion  15  in an image forming portion  3 . 
     Each developing portion  13  includes a developing case  37 . A magnet roller  38  for developing is provided in the developing case  37 . A bias having the same polarity as the charging polarity of the photoconductor drum  11  is applied to the magnet roller  38 . Toner  39  is electrically charged by the magnet roller  38 , and the charged toner  39  is flown onto an electrostatic latent image on the surface of the photoconductor drum  11  so as to develop the electrostatic latent image. The toner  39  is supplied from a toner container (not shown) via a toner supply port  40 . 
     The cleaning unit  15  includes a cleaning blade  41 , a cleaning roller  42 , a first screw member  43 , and a toner box  44 , wherein the cleaning blade  41  is a cleaning member. The cleaning blade  41  and the cleaning roller  42  have approximately the same length as the photoconductor drum  11 , and are configured to contact the photoconductor drum  11  and remove the residual waste toner from the surface of the photoconductor drum  11 . The removed waste toner is taken into the toner box  44  by the action of gravity or by the rotation of the cleaning roller  42 . Waste toner  45  taken into the toner box  44  is conveyed by the first screw member  43 . A discharge port (not shown) is formed in the right side wall of the toner box  44 . The first screw member  43  has a helical blade around a shaft body. The waste toner conveyed by the first screw member  43  is conveyed to the discharge port. 
     Each pair of the photoconductor drum  11  and the cleaning portion  15  is unitized as a drum unit  17  (see  FIG. 3 ). A plurality of discharge ports  3 A are formed in end portions of housings (not shown) of the drum units  17 . The discharge ports  3 A respectively communicate with the discharge ports that are formed in the right side walls of the toner boxes  44 . 
       FIG. 3  is a diagram for explaining flow paths in the image forming portions  3 , wherein toner and the like removed from the photoconductor drums  11  by the cleaning blades  41  and the cleaning rollers  42  flow in the flow paths until they are collected in a collection container  70  that is described below. As shown in  FIG. 3 , the toner removed by the cleaning members is conveyed as waste toner from left to right in conveyance paths  47  that extend in the left-right direction D 3  in the image forming apparatus  1 . The waste toner that has flown to the right end of the image forming portions  3  is discharged from the discharge ports  3 A provided at the right end of the drum units  17 , to a storage portion  50  that is described below. 
     Each developing portion  13  visualizes, with developer, an electrostatic latent image formed on the surface of the photoconductor drum  11 . As the developer, a two-component developer composed of toner and carrier is used. The toner is made of resin and the carrier is made of a magnetic material. Toner is smaller than carrier in particle size. As a result, toner is smaller than carrier in weight. In addition, an external additive is added to the developer. The external additive is, for example, a metal oxide such as silica, titanium oxide, alumina, or magnesium oxide. With the presence of the external additive, fluidity of toner is improved, toner is charged properly, or the performance of removing toner from the photoconductor drum  11  is improved. The carrier is magnetic particles composed of ferrite and the like. When a mixture of carrier and toner is stirred, toner is charged with static electricity that is generated by the friction between the toner and the carrier. With the presence of carrier, the two-component developer allows toner to be more easily charged than the one-component developer that is composed of only toner, thereby a high-quality image is made possible. 
     Among toner and carrier that compose the two-component developer, the toner is consumed in the image formation process. As a result, toner is supplied to the developing portions  13  from a tank (not shown) to supplement the consumed amount of toner. On the other hand, the carrier remains in the developing portions  13  without being consumed, and gives fluidity and the like to the toner that is newly supplied to the developing portions  13 . In this way, carrier is used for a longer period than toner. When carrier is used for a long period and stirred many times, the resin coat layer formed on the surface of carrier particles may peel off, or toner particles may stick to the surface of carrier particles. Due to such phenomena, carrier is deteriorated and its performance of giving the fluidity or the like is degraded. 
     In addition, although not shown, each developing portion  13  stirs the two-component developer by a second screw member (not shown) so as to charge toner sufficiently. The second screw member includes a helical blade around the shaft body. When the two-component developer remains in the developing portions  13  for a long period, toner particles change in shape and size due to friction between toner particles caused by the stirring operation in the developing portions  13 , and toner is deteriorated since the charging characteristic of toner changes. When an image is formed using such deteriorated toner, the charged amount of toner is reduced and fogging of toner or the like is likely to occur, which leads to degradation of image quality. 
     In the present embodiment, to avoid such a problem, a developing device of a so-called trickle development system is adopted, wherein in the trickle development system, old two-component developer is gradually discarded, and new two-component developer is gradually supplied. Hereinafter, the two-component developer that is discarded as such is referred to as waste developer. As described below, the waste developer is collected in the collection container  70  together with the waste toner that has been removed from the surface of the photoconductor drums  11 . 
     Each developing portion  13  of the trickle development system includes a developer storage portion  16  for storing the two-component developer. The developer storage portion  16  includes a partition wall  35  that is erected on a bottom surface (not shown) thereof along the longitudinal direction of the developing portion  13 . The inner space of the developer storage portion  16  is partitioned into two spaces S 1  and S 2  by the partition wall  35 . The two spaces S 1  and S 2  are communicated with each other at opposite ends of the developer storage portion  16  in the left-right direction D 3  (see arrows  31  and  32 ). In addition, the second screw member (not shown) is provided in each of the two spaces S 1  and S 2 . With the rotation of these second screw members, a circulation path  30  in which the two-component developer circulates in the spaces S 1  and S 2  of the developer storage portion  16  is formed. 
     In the right end portions of the developing cases  37  of the developing portions  13 , a plurality of discharge port portions  3 B (see  FIG. 3 ) are provided such that the two-component developer is discharged from the developing portions  13  to the storage portion  50  that is described below. Part of the circulating two-component developer is discharged to the storage portion  50  from the discharge port portions  3 B as the waste developer. 
       FIG. 4  is a diagram viewed from the arrow K 1  of  FIG. 3  and showing the internal configuration of the storage portion  50  that is described below.  FIG. 5  is an outer appearance perspective view of the storage portion  50  viewed from the arrow K 2  of  FIG. 3 . As shown in  FIG. 3  and  FIG. 4 , the image forming apparatus  1  includes the storage portion  50 . As shown in  FIG. 4 , the storage portion  50  includes an accumulation portion  50 A and a fan storage portion  50 B formed below the accumulation portion  50 A, wherein the waste toner and the waste developer are accumulated in the accumulation portion  50 A. 
     The accumulation portion  50 A includes a wall portion  55  (see  FIG. 4 ,  FIG. 5 ) that faces the end portions of one side of the image forming portions  3 . The wall portion  55  includes introduction port portions  501  and introduction port portions  502 , wherein the introduction port portions  501  communicate with the discharge ports  3 A, and the introduction port portions  502  communicate with the discharge port portions  3 B, respectively. A plurality of introduction port portions  501  are provided in correspondence with the plurality of discharge ports  3 A. A plurality of introduction port portions  502  are provided in correspondence with the plurality of discharge port portions  3 B. Waste toner that has reached the discharge ports  3 A is introduced, and falls, from the corresponding introduction port portions  501  into the accumulation portion  50 A. In addition, waste developer that has reached the discharge port portions  3 B is introduced, and falls, from the corresponding introduction port portions  502  into the accumulation portion  50 A. In this way, the accumulation portion  50 A temporarily stores waste toner and waste developer that have been discharged from the cleaning portions  15  and the developing portions  13  of the image forming portions  3 . 
     A screw member  83  is provided inside the accumulation portion  50 A. Specifically, the accumulation portion  50 A includes a wall portion  56  and a wall portion  57 , wherein the wall portion  56  intersects with the rear-side edge of the wall portion  55 , and the wall portion  57  intersects with the front-side edge of the wall portion  55 . The screw member  83  is rotatably supported by a bearing  300  provided on the wall portion  56  and a bearing  301  provided on the wall portion  57  in the state where the screw member  83  is passed through and suspended by the wall portion  56  and the wall portion  57 . The screw member  83  is rotationally driven by a drive motor (not shown). The accumulation portion  50 A is connected with the collection container  70 . The waste toner and the waste developer accumulated in the accumulation portion  50 A are conveyed to the collection container  70  (see  FIG. 3 ,  FIG. 7 ) as the screw member  83  rotates, and are collected in the collection container  70 . The accumulation portion  50 A forms a toner conveyance passage between the developing portions  13  and the collection container  70  that collects the toner discharged from the developing portions  13 . The accumulation portion  50 A of the storage portion  50  is an example of the toner conveyance portion of the present disclosure, and the screw member  83  is an example of the conveyance member of the present disclosure. The fan storage portion  50 B is described below. 
     Meanwhile, toner in the developing portions  13  is likely to be scattered. As a result, when an air pressure inside the developing portions  13  is higher than an air pressure outside thereof, tonner scattered inside the developing portions  13  may leak to the outside. When toner leaks to outside of the developing portions  13 , inside and outside of the image forming apparatus  1  may be contaminated by the toner. To prevent this, conventionally, a suction nozzle is provided in the vicinity of the developing portions  13  such that scattered toner is sucked by a fan and trapped by a filter, thereby restricting the toner from being scattered in the peripheral of the developing portions  13 . 
     However, according to the conventional configuration, a dedicated collection box for collecting the trapped toner is required. The provision of the dedicated collection box increases the number of components and increases the size of the apparatus. In addition, the provision of the dedicated collection box leads to increase of manufacturing cost of the apparatus. 
     In view of the above-described problems, the image forming apparatus  1  of the present embodiment is provided with a trapping mechanism  100  for trapping the scattered toner in the developing portions  13  by using the configuration where the inner spaces of the developing portions  13  are communicated with the inner space of the storage portion  50  via the discharge port portions  3 B and the introduction port portions  502 , wherein the trapping mechanism  100  is described below. 
     As shown in  FIG. 4  to  FIG. 7 , the trapping mechanism  100  includes vent hole portions  101 , vent passage portions  102 , an air suction portion  103 , and a trapping portion  104 . 
     The vent hole portions  101  are formed in the wall portion  55  of the accumulation portion  50 A in such a way as to pass through the wall portion  55  to the vent passage portions  102  side. In the present embodiment, the vent hole portions  101  are formed in the vicinity of the introduction port portions  502 . With this configuration, if the waste toner among the waste developer introduced from the introduction port portions  502  into the accumulation portion  50 A, is scattered, the scattered toner is trapped before it is scattered over the whole accumulation portion  50 A. In addition, a plurality of vent hole portions  101  are provided in correspondence with the plurality of introduction port portions  502 . 
     At an end part of each vent hole portion  101 , an eaves portion  101 A, a side wall portion  101 B, and a side wall portion  101 C are provided. As shown in  FIG. 4  and  FIG. 6 , the eaves portion  101 A projects from the upper end part of the vent hole portion  101  toward the inside of the accumulation portion  50 A (the right side in  FIG. 4 ). The side wall portion  101 B and the side wall portion  101 C are provided respectively at end parts of both sides of each vent hole portion  101 . A vent hole H 1  is formed such that its top and sides are surrounded by the eaves portion  101 A, the side wall portion  101 B, and the side wall portion  101 C. With this configuration, part of the scattered toner that has entered the storage portion  50  via the introduction port portions  502  collides with the eaves portion  101 A, the side wall portion  101 B, and the side wall portion  101 C and falls, and the remaining scattered toner reaches the vent hole H 1  by going around the eaves portion  101 A, the side wall portion  101 B, and the side wall portion  101 C. 
     As shown in  FIG. 5 , the vent passage portions  102  are formed on an outer wall surface  59  of the wall portion  55  of the accumulation portion  50 A. In the present embodiment, the vent passage portions  102  are each formed in the shape of a pipe, and are formed in correspondence with the vent hole portions  101 . Ends of the inner spaces of the vent passage portions  102  on one side are respectively communicated with the vent holes H 1 , and ends of the inner spaces of the vent passage portions  102  on the other side merge at a merge portion  109 , and the inner space of the merge portion  109  is communicated with the inner space of the fan storage portion  50 B. In this way, the vent hole portions  101  allow inside and outside of the accumulation portion  50 A to communicate with each other such that air can be ventilated between the inside and the outside of the accumulation portion  50 A. The vent hole portions  101  are an example of the vent hole portion of the present disclosure. 
     The air suction portion  103  is, for example, an axial fan. The fan storage portion  50 B is in the shape of a cylinder with no bottom, and the air suction portion  103  is stored in the fan storage portion  50 B. The air suction portion  103  exhausts air to outside of the fan storage portion  50 B (see arrows X in  FIG. 4 ). In this way, the air suction portion  103  sucks the air inside the accumulation portion  50 A via the vent hole portions  101 . The air suction portion  103  is an example of the air suction portion of the present disclosure. 
     The trapping portion  104  includes filter portions  105  and toner removing members  106  (an example of the toner removing portion of the present disclosure). The filter portions  105  are respectively provided on the vent hole portions  101 . The filter portions  105  are provided in such a way as to cover the vent holes H 1  formed in the vent hole portions  101 , from the inner side. Specifically, as shown in  FIG. 6 , each filter portion  105  is attached to the eaves portion  101 A, the side wall portion  101 B, and the side wall portion  101 C so as to cover an opening from a tip part (projection end) of the eaves portion  101 A to a lower end part of each vent hole portion  101 . The filter portions  105  have a mesh whose size is smaller than scattered toner particles such that the scattered toner particles cannot pass therethrough. In this way, the filter portions  105  trap the scattered toner contained in the air sucked by the air suction portion  103 . The filter portions  105  correspond to the filter portion of the present disclosure. 
     As shown in  FIG. 6 , the toner removing member  106  is configured to remove, from the filter portions  105 , the scattered toner that has been trapped by the filter portions  105 . Specifically, the toner removing member  106  includes a shaft portion  106 A and a scraping paddle portion  106 B. As shown in  FIG. 4 , similar to the screw member  83 , the toner removing member  106  is rotatably supported by a bearing  302  and a bearing  303  in the state where the toner removing member  106  is passed through and suspended by the wall portion  56  and the wall portion  57 . The toner removing member  106  is installed in the accumulation portion  50 A such that the shaft portion  106 A is parallel to the screw member  83 . 
     As shown in  FIG. 4 , the image forming apparatus  1  includes a drive transmission mechanism  200 . The drive transmission mechanism  200  includes a gear  201  and a gear  202 . The gear  201  is provided on the same axis as the screw member  83  and is attached to one end of the screw member  83  that has been passed through the wall portion  56  of the accumulation portion  50 A to the outside. The gear  202  is provided on the same axis as the toner removing member  106  and is attached to one end of the shaft portion  106 A that has been passed through the wall portion  56  of the accumulation portion  50 A to the outside. The gear  201  and the gear  202  mesh with each other. The gear  201  provided on the screw member  83  is rotated together with the screw member  83  by a driving force of the drive motor that rotationally drives the screw member  83 . As a result, the driving force of the drive motor is transmitted to the gear  202  provided on the toner removing member  106  by the gear  201 . This allows the toner removing member  106  to rotate around the axis. In this way, the drive transmission mechanism  200  transmits the driving force input from the drive motor rotationally driving the screw member  83 , to the shaft portion and causes the scraping paddle portion  106 B to rotate together with the shaft portion  106 A. 
     As shown in  FIG. 6 , the scraping paddle portion  106 B is provided on the shaft portion  106 A at a position facing the vent hole portions  101 . The scraping paddle portion  106 B extends from the circumferential surface of the shaft portion  106 A in a direction of intersecting with the axis of the shaft portion  106 A, and is made of a material that has an elastic force. The scraping paddle portion  106 B is configured such that its tip part contacts the filter portions  105  when the rotation position of the shaft portion  106 A is within a predetermined position range. When the tip part of the scraping paddle portion  106 B contacts the filter portions  105 , the scraping paddle portion  106 B scrapes off the waste toner that has stuck to the filter portions  105 . The waste toner scraped off from the filter portions  105  by the toner removing member  106  falls (see the arrow Q 1  in  FIG. 6 ). As a result, the waste toner that has been trapped by the filter portions  105  is also conveyed to the collection container  70  by the screw member  83 , and is collected in the collection container  70 . 
     In the trapping mechanism  100  having the above-described configuration, as shown in  FIG. 7 , when the air suction portion  103  is activated, the air inside the accumulation portion  50 A is sucked via the vent passage portions  102  and the vent hole portions  101 . Furthermore, since the inner space of the storage portion  50  is communicated with the inner spaces of the developing portions  13  via the introduction port portions  502  and the discharge port portions  3 B, the air inside the developing portions  13  is sucked. 
     As a result, the air and the scattered toner inside the developing portions  13  are introduced into the accumulation portion  50 A of the storage portion  50  via the discharge port portions  3 B and the introduction port portions  502 , and further flow toward the vent hole portions  101 . Here, the air passes through the filter portions  105  of the trapping portion  104  and the vent holes H 1 , is introduced into the inner space of the fan storage portion  50 B by passing through the vent passage portions  102  and the merge portion  109 , and is discharged to outside by the air suction portion  103 . On the other hand, the scattered toner that flows toward the vent hole portions  101  by going around each eaves portion  101 A, side wall portion  101 B, and side wall portion  101 C, is dammed by the filter portions  105 , and sticks to the filter portions  105  or collides with the filter portions  105  and then naturally falls. The toner that has stuck to the filter portions  105  is scraped off by the scraping paddle portion  106 B and falls. The fallen toner is conveyed to the collection container  70  by the screw member  83  together with the waste toner and the waste developer accumulated in the accumulation portion  50 A, and is collected in the collection container  70 . 
     The above-described configuration makes it possible to trap toner that has been scattered in the developing portions  13 , and prevent the toner from being scattered in the peripheral of the developing portions  13 . In addition, compared to the case where a dedicated box is provided to collect the trapped toner, the above-described configuration can prevent increase in the number of components and the size of the image forming apparatus, and prevent increase of the cost. 
     In the above-described embodiment, the present disclosure is applied to the configuration where the storage portion  50  is provided between the developing portions  13  and the collection container  70  and the storage portion  50  forms the toner conveyance portion. However, the application target of the present disclosure is not limited to the configuration including the storage portion  50 , but may be any configuration that, as shown in  FIG. 8 , includes a toner conveyance portion  602  forming a toner conveyance passage between a developing portion  600  and a collection container  601 . 
     That is, the essence of the image forming apparatus of the present disclosure is to include the toner conveyance portion  602 , a vent hole portion  603 , an air suction portion  604 , and a filter portion  605 . The vent hole portion  603  is formed in the toner conveyance portion  602  and allows inside and outside of the toner conveyance portion to communicate with each other such that air can be ventilated between the inside and the outside of the toner conveyance portion. The air suction portion  604  sucks the air inside the toner conveyance portion  602  via the vent hole portion  603 . The filter portion  605  is provided on the vent hole portion  603  and traps the toner included in the air sucked by the air suction portion  604 . 
     It is to be understood that the embodiments herein are illustrative and not restrictive, since the scope of the disclosure is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.