Patent Publication Number: US-10317837-B2

Title: Toner collection container and image forming device including the same

Description:
The entire disclosure of Japanese patent Application No. 2017-132619, filed on Jul. 6, 2017, is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Technological Field 
     The present invention relates to an image forming device, and particularly relates to a structure of a toner collection container. 
     Description of the Related Art 
     An electrophotographic image forming device such as a laser printer, a copying machine, or a multifunction peripheral (MFP) generally has a toner collection container (refer to JP 2016-138984 A, JP 2016-045353A, and JP 05-066643A). The “toner collection container” represents a container in order that an electrophotographic image forming device may store toner removed from a photoreceptor or an intermediate transfer member mainly in a cleaning step. The image forming device forms a toner image on a surface of the photoreceptor and transfers the toner image directly from the photoreceptor to a sheet via the intermediate transfer member. Generally, the toner remains on the surfaces of the photoreceptor and intermediate transfer member after transfer, and a foreign matter such as paper dust adheres from the sheet. In the cleaning step, the image forming device scrapes off the above-described residual toner and foreign matter (hereinafter collectively referred to as “waste toner”) from the surfaces of the photoreceptor and intermediate transfer member with a blade or a brush, and collects the waste toner in the toner collection container. The image forming device monitors an amount of such waste toner with a toner sensor (refer to JP 2016-138984 A and JP 2016-045353 A), and in a case of detecting that the toner collection container is full with the waste toner, a user is urged to replace the toner collection container by an indication on an operation panel or the like. Normally, a full toner collection container is disposable and discarded together with stored waste toner. 
     Preferably, a toner collection container has a large storable amount of waste toner. The larger the storable amount of waste toner is, the longer the image forming device is used before the container becomes full, and therefore, frequency of toner replacement is reduced and burden on a user required for replacing the container is reduced. 
     Preferably, a toner collection container is arranged inside a front face of an image forming device (refer to JP 2016-138984 A, for example). There may a case where optional devices such as a sheet feeding device and a post processing device are additionally provided on both sides of an image forming device, and therefore, in a case where the toner collection container is arranged inside the front face which is a place not hindered by such optional devices, a user can easily handle the container. 
     Additionally, it is necessary for a toner collection container not to hinder an airflow inside an image forming device. The image forming device introduces external air from a front face and exhausts internal air from a rear face by utilizing a built-in fan, for example. With such ventilation, for example, the image forming device diffuses, to the external air, ozone generated in a charging step and cools: a motor that drives a conveyance roller, a photoreceptor drum, an intermediate transfer belt, and the like; a control circuit of the motor; a heat generation member such as a fixing roller; and a power source. A ventilation passage (also referred to as an air duct) having a sufficiently large cross-sectional area is secured around the toner collection container such that the above-described effects provided by ventilation can be sufficiently obtained. For example, according to the image forming device disclosed in JP 05-066643 A, side walls of the toner collection container is also used as one face of a duct adapted to cool a light source. 
     Generally, a toner collection container has low strength against impact. The reason is that the container is usually disposable, and therefore, a typical material thereof is a material such as plastic or paper that can be easily treated after discarded. In a case where a user mistakenly slips a container out of the hand and drops the same on a floor at the time of replacement, an outer surface of the container subjected to direct impact of the floor is likely to be damaged, for example, dented or cracked. Furthermore, at the moment of collision with the floor, pressure (powder pressure) of stored waste toner rapidly is concentrated on a part of an inner face of the container close to the floor, and therefore, a boundary with other parts is likely to be damaged, for example, flawed. 
     The toner collection container is also easily deformed by weight of waste toner. Particularly, when a container has a longer length in one direction than in another direction, the container tends to be deflected in a longitudinal direction. The reason is that rigidity of a typical material thereof is low. In a case where the container is excessively deformed, a full-state detection error by the toner sensor of the image forming device may exceed an allowable range. 
     To prevent damage on the toner collection container by impact in a fall and to suppress the full-state detection error caused by deformation of the container within the allowable range, it is advisable to adopt, as a material of the container, a substance having high strength such as reinforced plastic or a metal. However, in this case, treatment after being discarded becomes difficult, and moreover, a low manufacturing cost can be hardly kept. 
     In recent years, it is further difficult to prevent a toner collection container from hindering an airflow inside an image forming device while keeping a sufficiently large storable amount of waste toner. The reason is that a ratio of a volume occupied by a toner collection container inside an image forming device is increased and a gap around the toner collection container is narrowed as a result of rapid progress in miniaturization of image forming devices along with wide spread use in small offices/home offices and households. 
     SUMMARY 
     An object of the present invention is to solve the above-described problems, and particularly to provide a toner collection container that: prevents damage by impact in a fall and deformation caused by the weight of the waste toner regardless of strength and rigidity of a material; and does not hinder an airflow inside an image forming device even while keeping a sufficiently large storable amount of waste toner. 
     To achieve the abovementioned object, according to an aspect of the present invention, there is provided a toner collection container detachably incorporated in an electrophotographic image forming device in order to collect toner to be discarded from an image former of the image forming device, and the toner collection container reflecting one aspect of the present invention comprises: a housing including a hollow capable of storing discarded toner, and incorporated between an air inlet port and the image former in a space surrounded by a chassis of the image forming device, the air inlet port introducing external air into the space; and at least one duct being formed of a cylindrical or tubular member that penetrates a storing region in the hollow of the housing from a side closer to the air inlet port to a side closer to the image former out of side walls of the housing, or formed of a recess included in a bottom surface of the housing and recessed toward the storing region, the storing region actually storing the toner, and the duct guiding external air flowing from the air inlet port to a side where the image former is positioned. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention: 
         FIG. 1A  is a perspective view illustrating an external view of an image forming device according to an embodiment of the present invention; 
         FIG. 1B  is a front view schematically illustrating an internal structure of a printer included in the device; 
         FIG. 2A  is a perspective view illustrating an external view of the printer in a state in which front doors of a body of the image forming device illustrated in  FIGS. 1A and 1B  are opened; 
         FIG. 2B  is a schematic vertical cross-sectional view of the printer taken along a line b-b illustrated in  FIG. 2A ; 
         FIG. 3A  is a perspective view illustrating an external view from a position where a front face of a toner collection container according to an embodiment of the present invention is visible; 
         FIG. 3B  is a perspective view illustrating an external view from a position where a rear face thereof is visible; 
         FIG. 4A  is a vertical cross-sectional view of the container taken along a line IVa-IVa illustrated in  FIGS. 3A and 3B ; 
         FIG. 4B  is a vertical cross-sectional view of the container taken along a line IVb-IVb illustrated in  FIGS. 3A and 3B ; 
         FIG. 5A  is a perspective view illustrating an external view from a position where a front face of a first modified example of the toner collection container according to the embodiment of the present invention is visible; 
         FIG. 5B  is a perspective view illustrating an external view from a position where a rear face thereof is visible; 
         FIG. 6A  is a perspective view illustrating an external view from a position where a front face of a second modified example of the toner collection container according to the embodiment of the present invention is visible; 
         FIG. 6B  is a perspective view illustrating an external view from a position where a rear face thereof is visible; 
         FIG. 7A  is a perspective view illustrating an external view from a position where a front face of a third modified example of the toner collection container according to the embodiment of the present invention is visible; 
         FIG. 7B  is a perspective view illustrating an external view from a position where a rear face thereof is visible; 
         FIG. 8A  is a perspective view illustrating an external view of a printer in which a fourth modified example of the toner collection container according to the embodiment of the present invention is incorporated; 
         FIG. 8B  is a schematic vertical cross-sectional view of the printer taken along a line b-b illustrated in  FIG. 8A ; 
         FIG. 9A  is a perspective view illustrating an external view from a position where a front face of the toner collection container according to the fourth modified example is visible: 
         FIG. 9B  is a perspective view illustrating an external view from a position where a rear face thereof is visible; 
         FIG. 10A  is a front view of the container illustrated in  FIG. 9A ; 
         FIG. 10B  is a rear view of the container illustrated in  FIG. 9B ; 
         FIG. 11  is a perspective view illustrating an external view of a printer in which a fifth modified example of the toner collection container according to the embodiment of the present invention is incorporated; 
         FIG. 12A  is a perspective view illustrating an external view from a position where a front face of the toner collection container according to the fifth modified example is visible; and 
         FIG. 12B  is a perspective view illustrating an external view from a position where a rear face thereof is visible. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. 
     [External View of Image Forming Device] 
       FIG. 1A  is a perspective view illustrating an external view of an image forming device according to an embodiment of the present invention. The image forming device is a multi-function peripheral (MFP)  100  and has functions of a scanner, a color copy machine, and a color printer. An auto document feeder (ADF)  110  is mounted on an upper surface of a housing (hereinafter referred to as “body”) of the MFP  100  in an openable manner. A scanner  120  is built in an upper part of the body positioned immediately below the ADF  110 , and a printer  130  is built in a lower part of the body. Three front doors  131 ,  132 , and  133  are attached to a front face in the upper part of the printer  130  in an openable manner, and a plurality of stages of sheet feeding cassettes is attached to a lower part  134  in a removable manner. 
     The MFP  100  is an internal sheet ejection type, and a sheet ejection tray  46  is installed in a gap DSP between the scanner  120  and the printer  130 , and stores a sheet ejected from a sheet ejection port (not illustrated) located on a deeper side thereof. An operation panel  51  is attached to a part included in a front face of the body and positioned beside the gap DSP. The operation panel  51  has a front face embedded with a touch panel, and various mechanical push buttons are arranged around the touch panel. 
     [Structure of Printer] 
       FIG. 1B  is a front view schematically illustrating an internal structure of the printer  130 . Note that elements of the printer  130  are illustrated in a manner seen through the front face of the body in  FIG. 1B . The printer  130  is an electrophotographic color printer, and includes a sheet feeder  10 , an image former  20 , a fixing unit  30 , and an sheet ejector  40  in a space surrounded by a chassis (not illustrated) that supports the body. These elements  10  to  40  are cooperatively operated to form a color image on a sheet with toner on the basis of image data while conveying the sheet in the space surrounded by the chassis. 
     The sheet feeder  10  separates, one by one, a sheet SH 1  from a bundle of sheets SHT stored in a sheet feeding cassette  11  by utilizing a group of conveyance rollers  12 ,  13 , and  14 , and feeds the sheet SH 1  to the image former  20 . A material of a sheet that can be stored in the sheet feeding cassette  11  includes paper and a resin, and types of the paper may include high quality paper, color paper, and coated paper. Sheet sizes include not only standard sizes specified by the JIS standard, such as A3 to A7 and B4 to B7, but also sizes of a business card, a bookmark, a ticket, a postcard, an envelope, and a photograph (L size). Sheet postures can be set in any one of longitudinal arrangement and lateral arrangement. 
     The image former  20  forms a toner image on a sheet SH 2  conveyed from the sheet feeder  10 . Specifically, in each of the four image forming units  21 Y,  21 M,  21 C, and  21 K, a photoreceptor drum  25  is rotated, and simultaneously electricity is discharged between an electric charger  26  and a surface thereof to charge the surface. Next, a charged part of the photoreceptor drum  25  is irradiated with laser light from an exposure unit  27 . The exposure unit  27  changes an amount of laser light to be emitted to each different image forming unit on the basis of a gradation value of each different color out of gradation values of the four colors of yellow (Y), magenta (M), cyan (C), and black (K). Therefore, electrostatic latent images of different colors are formed on surfaces of different photoreceptor drums  25 . Subsequently, toner that covers a surface of a developing roller  28  contacts the surfaces of the photoreceptor drums  25  to develop an electrostatic latent image on the surface thereof. In each of the different image forming units, there is toner of one different color out of Y, M, C and K, and therefore, toner images of Y, M, C, and K are formed one by one on the respective surfaces of the four photoreceptor drums  25 . When each toner image passes through a nip between a photoreceptor drum  25  and a primary transfer roller  22 , each image is transferred from the surface of the photoreceptor drum  25  to a surface of an intermediate transfer belt  23  by electric field therebetween. Thus, four single color toner images are transferred onto the intermediate transfer belt  23  in a superimposed manner, and one color toner image is formed. When this color toner image passes through a nip between a drive roller  23 R of the intermediate transfer belt  23  and a secondary transfer roller  24 , the color toner image is transferred by an electric field between the two rollers  23 R and  24  to a surface of the sheet SH 2  simultaneously made to pass through the same nip. 
     The fixing unit  30  thermally fixes the toner image on the sheet SH 2  conveyed from the image former  20 . Specifically, when this sheet SH 2  is made to pass through a nip between a fixing roller  31  and a pressure roller  32 , the fixing roller  31  applies heat of a built-in heater to the surface of the sheet SH 2 , and the pressure roller  32  presses the heated part of the sheet SH 2  against the fixing roller  31  by applying pressure. The toner image is fixed on the surface of the sheet SH 2  by the heat from the fixing roller  31  and the pressure from the pressure roller  32 . 
     The sheet ejector  40  ejects a sheet SH 3  conveyed from the fixing unit  30  from a sheet ejection port  42  by a sheet ejection roller  43 , and stores the sheet SH 3  in the sheet ejection tray  46 . 
     Cleaner 
     A surface of each photoreceptor drum  25  contacts a cleaning blade  29  after contacting the primary transfer roller  22 . The cleaning blade  29  is a thin long rectangular plate-like member made of a thermosetting resin such as polyurethane rubber, and has a length substantially equal that of the photoreceptor drum  25  (size in a normal direction of a sheet surface in  FIG. 1B ). An end face (edge) of the blade  29  extending in a longitudinal direction (in the normal direction of the sheet surface in  FIG. 1B ) obliquely contacts the surface of the photoreceptor drum  25 , and scrapes residual toner and other foreign matters from surface of the photoreceptor drum  25  with rotation of the photoreceptor drum. 
     The surface of the intermediate transfer belt  23  contacts a cleaning blade  23 C after passing through the nip between the drive roller  23 R and the secondary transfer roller  24 . The cleaning blade  23 C is a thin long rectangular plate-like member made of a thermosetting resin such as polyurethane rubber, and has a length substantially equal to that of the intermediate transfer belt  23  (size in the normal direction of a sheet surface in  FIG. 1B ). An end face (edge) of the blade  23 C extending in the longitudinal direction (in the normal direction of the sheet surface in  FIG. 1B ) obliquely contacts the surface of the intermediate transfer belt  23 , and scrapes residual toner and foreign matters like paper dust from the surface of the intermediate transfer belt  23  with rotation of the intermediate transfer belt. 
     Toner Replenishing Unit 
       FIG. 2A  is a perspective view illustrating an external view of the printer  130  in a state in which front doors  131  to  133  of the body of the MFP  100  are opened, and  FIG. 2B  is a schematic vertical cross-sectional view of the printer  130  taken along a line b-b illustrated in  FIG. 2A . As illustrated in  FIGS. 2A and 2B , a toner replenishing unit  60  is built in immediately below the sheet ejection tray  46  inside the body of the MFP  100 . When the front doors  131  and  132  are opened, a front face of the replenishing unit  60  is exposed to the outside. Four toner bottles  60 Y,  60 M,  60 C, and  60 K can be freely inserted into and removed from four holes  61  opened on the front face. Each of the toner bottles  60 Y to  60 K has a thin long cylindrical shape and contains toner of one different color out of Y, M, C and K. In a deeper side of each hole  61  (on a right side in  FIG. 2B ), an end of an inserted toner bottle is rotatably held by a mechanism  62  of the replenishing unit  60 . The mechanism  62  rotates each toner bottle around an axis thereof with a motor (not illustrated). Along with this rotation, the replenishing unit  60  captures toner spilled from each bottle, and conveys the toner to a developing roller  28  of each image forming unit by utilizing, for example, a screw. 
     Toner Collector 
     As further illustrated in  FIGS. 2A and 2B , in a space immediately below the replenishing unit  60  inside the body of the MFP  100 , the toner collection container  70  is incorporated between inner faces of the front doors  131  to  133  and the image former  20  in a detachable manner. Since the toner collection container  70  is exposed to the outside when the front doors  131  to  133  are opened, a user can easily handle the container  70 . A toner collector (not illustrated) is installed on a rear side of the container  70 . The collector is a mechanism such as a screw that conveys residual toner and foreign matters such as paper dust (hereinafter collectively referred to as “waste toner”) from the image former  20  to the container  70 , and causes the conveyed waste toner to flow into the container  70  from a hole on the rear face thereof. The waste toner is mainly collected by the cleaners in the image former  20 , and in the example illustrated in  FIG. 1B , the cleaner includes the cleaning blade  23 C contacting the intermediate transfer belt  23  and the cleaning blade  29  included in each of the image forming units  21 Y to  21 K. A structure of the toner collection container  70  will be described more in detail later. 
     The collector further includes a toner sensor (not illustrated) in a region facing the rear face of the container  70  when the toner collection container  70  is incorporated in the printer  130 . The toner sensor is, for example, an optical type, and monitors an interface between waste toner stored in the container  70  and internal air of the container  70 , and when a height of the interface reaches an allowable upper limit, the toner sensor detects a full state of waste toner in the container  70 . The toner sensor will be described more in detail later. 
     Ventilation Structure 
       FIGS. 2A and 2B  also illustrate air inlet port  80 , a fan  81 , and an air outlet port  82 . The air inlet port  80  is a hole opened on the front door  133  of the body of the MFP  100 , and provides communication between an inner space of the body and the outside thereof. The fan  81  is installed inside the front door  133  of the body, particularly, on a deeper side of the air inlet port  80 . The air outlet port  82  is a hole opened on the rear face  135  of the body of the MFP  100 , and provides communication between the inner space of the body and the outside thereof. With rotation of the fan  81 , the external air is introduced into the inside of the body from the air inlet port  80 , and the air inside the body is exhausted to the outside from the air outlet port  82 . With this structure, airflows directed from the air inlet port  80  to the air outlet port  82  are generated in the space inside the body, as indicated by one-dot chain lines in  FIG. 2B . These airflows mainly pass through a space surrounded by the intermediate transfer belt  23  and a gap between the exposure unit  27  and the image forming units  21 Y to  21 K in the image former  20 , and flow into a drive unit  90  installed between the image former  20  and the rear face  135  of the body. The drive unit  90  is an assembly of a motor and a control circuit thereof, and the motor drives the conveyance rollers  12  to  14  of the sheet feeder  10 , the photoreceptor drums  25 , the developing rollers  28 , and the drive roller  23 R of the intermediate transfer belt  23  illustrated in  FIG. 1B . The airflow having passed through the drive unit  90  escapes from the air outlet port  82  to the external air. Since the airflow thus flows from the air inlet port  80  to the air outlet port  82 , ozone generated due to discharge at the electric charger  26  is released to the external air, and the motor and the control circuit included in the drive unit  90  and the exposure unit  27  are cooled. 
     As illustrated in  FIGS. 2A and 2B , the toner collection container  70  is incorporated in a gap between the air inlet port  80  and the image former  20 . The gap between this container  70  and members surrounding the same, such as the replenishing unit  60 , is narrow. However, the container  70  includes four ducts  71 Y,  71 M,  71 C, and  71 K. Each of the ducts  71 Y to  71 K penetrates the inside of the container  70  from a side closer to the air inlet port  80  to a side closer to the image former  20  out of side walls of the container  70 . With this structure, each of the ducts  71 Y to  71 K guides the external air flowing from the air inlet port  80  to the space surrounded by the intermediate transfer belt  23  and the gap between the image forming units  21 Y to  21 K and the exposure unit  27 . Since the ducts  71 Y to  71 K thus function as ventilation passages, a large amount of the external air flowing into the drive unit  90  through the image former  20  from the air inlet port  80  can be secured despite a fact that the gap around the toner collection container  70  is narrow. As a result, even in a case where the toner collection container  70  blocks a large part of the space inside the front door  133 , both of an effect of removing ozone from the image former  20  by ventilation and an effect of cooling the drive unit  90  and the exposure unit  27  are sufficiently high. 
     [Structure of Toner Collection Container] 
       FIG. 3A  is a perspective view illustrating an external view from a position where a front face of the toner collection container  70  is visible, and  FIG. 3B  is a perspective view illustrating an external view from a position where a rear face thereof is visible. In  FIGS. 3A and 3B , the front and rear faces of the container  70  are partially removed and an internal structure of the container  70  is visible.  FIG. 4A  is a vertical cross-sectional view of the container  70  taken along a line IVa-IVa illustrated in  FIGS. 3A and 3B , and  FIG. 4B  is a vertical cross-sectional view of the container  70  taken along a line IVb-IVb illustrated in  FIGS. 3A and 3B ; 
     Housing 
     A housing  72  of the toner collection container  70  is, for example, a hollow rectangular plate-like member made of a thermoplastic resin such as polycarbonate that is easily reused, and has a longer length in one direction than in another direction. As illustrated in  FIGS. 2A and 2B , a longitudinal direction of the housing  72  is horizontal inside the printer  130 , and a front wall  72 F and a rear wall  72 R are parallel to the front face of the body. As illustrated in  FIG. 3A , four round holes  74 Y,  74 M,  74 C, and  74 K are opened on the front wall  72 F of the housing  72 . Each of the round holes  74 Y to  74 K has a round circumference and is positioned in the vicinity of the fan  81  inside the printer  130  as illustrated in  FIG. 2B . As illustrated in  FIG. 3B , four vertical holes  75 Y,  75 M,  75 C, and  75 K are opened on the rear wall  72 R of the housing  72 . Each of the vertical holes  75 Y to  75 K has a rectangle shape having a long length in a short side direction of the rear wall  72 R, and a lower end thereof is rounded like a semicircular shape. As illustrated in  FIG. 2B , inside the printer  130 , each of the lower ends of the vertical holes  75 Y to  75 K faces a different image forming unit out of the image forming units  21 Y to  21 K, and upper ends thereof face a space surrounded by the intermediate transfer belt  23 . 
     Duct 
     As illustrated in  FIG. 4B , each of the ducts  71 Y to  71 K has a cylindrical shape having a uniform radius in an axial direction, and extends perpendicular to the respective walls  72 F and  72 R from the front wall  72 F close to the air inlet port to the rear wall  72 R close to the image former  20  out of the side walls of the housing  72 , and penetrates a hollow  72 H inside the housing  72 . Each of the ducts  71 Y to  71 K provides communication between one different round hole of the round holes  74 Y to  74 K and one different lower end of those of the vertical holes  75 Y to  75 K. With this structure, the ducts  71 Y to  71 K guide the external air introduced by the fan  81  from the round holes  74 Y to  74 K to the image forming units  21 Y to  21 K through the lower ends of the vertical holes  75 Y to  75 K. As illustrated in  FIGS. 4A and 4B , the respective ducts are coaxial with the round holes and the semicircles at the lower ends of the vertical holes for which the ducts provide communication, and the ducts have radii same as those of the round holes and the semicircles. Particularly, the duct  71 K, the round hole  74 K, and the vertical hole  75 K forming a ventilation passage to the image forming unit  21 K for the color K have a cross-sectional area larger than the cross-sectional areas of the other ducts. With this structure, the air included in the external air introduced by the fan  81  and flowing through the duct  71 K has a ratio of a flow rate larger than a ratio of a flow rate of the air that flows through each of other ducts  71 Y to  71 C. The reason is that: use frequency of the image forming unit  21 K for the color K is higher than use frequency of the image forming units  21 Y to  21 C for other three colors Y, M and C, and therefore, an ozone generation amount and a heat generation amount in the motor or the like are large, and a large amount of ventilation is required in the image forming unit  21 K. 
     Guide Passage 
     As illustrated in  FIGS. 3A, 3B, 4A, and 4B , vertical walls  76 Y,  76 M,  76 C, and  76 K extend upward along an inner side of the rear wall  72 R of the housing  72  respectively from connecting portions between the ducts  71 Y to  71 K and the lower ends of the vertical holes  75 Y to  75 K. The vertical walls  76 Y to  76 K block the vertical holes  75 Y to  75 K from the inner sides, and isolate the hollow  72 H of the housing  72  from the outside, and also secure gaps inside the respective vertical holes. Regions between the upper ends and the lower ends of the vertical holes  75 Y to  75 K are blocked from the outside by thin plate-like members  77 Y,  77 M,  77 C, and  77 K each made of a resin, for example. With this structure, respective gaps between the plate-like members  77 Y to  77 K and the vertical walls  76 Y to  76 K illustrated in  FIG. 4B  function as guide passages to guide airflows sent from the fan  81  to the upper ends of the vertical holes  75 Y to  75 K from the ducts  71 Y to  71 K. The upper ends of the vertical holes  75 Y to  75 K face the space surrounded by the intermediate transfer belt  23 , and the motor to drive the photoreceptor drums  25 , the developing rollers  28 , and drive roller  23 R of the intermediate transfer belt  23 , and the control circuit thereof are arranged in the drive unit  90  located in a deeper side of the space. The airflows having passed through the ducts  71 Y to  71 K are also branched into the guide passages (vertical walls)  76 Y to  76 K, and released from the upper ends of the vertical holes  75 Y to  75 K into the space surrounded by the intermediate transfer belt  23 . With this structure, an air cooling effect for the motor of the drive unit  90  and the like can be highly maintained. 
     Receiving Port for Waste Toner 
     As illustrated in  FIGS. 3A, 3B, and 4A , five penetration holes  78 I,  78 Y,  78 M,  78 C, and  78 K are opened on an upper part of the rear wall  72 R of the housing  72 . All of the holes  78 I to  78 K have equal radii. The hole  78 I located at an upper left corner of the rear wall  72 R illustrated in  FIG. 3B  is located at a height higher than at heights of other four holes  78 Y to  78 K from a bottom surface  72 B of the housing  72 , and other four holes  78 Y to  78 K are located at the equal heights. Inside the printer  130 , the hole  78 I located at the upper left corner is connected to a storage chamber (not illustrated) of waste toner scraped by the cleaning blade  23 C for the intermediate transfer belt, and the other four holes  78 Y to  78 K are connected to storage chambers (not illustrated) to store waste toner scraped by the cleaning blades  29  of the different image forming units, respectively. With this structure, the holes  78 I to  78 K function as receiving ports for waste toner from the intermediate transfer belt  23  and the image forming units  21 Y to  21 K. In the following, note that the waste toner receiving port  78 I from the intermediate transfer belt  23  will be referred to as “color toner receiving port”, and waste toner receiving ports  78 Y to  78 K from the image forming units  21 Y to  21 K for the respective single colors of Y, M, C and K will be referred to as “Y, M, C, K toner receiving ports”. 
     Leveling Member 
     As illustrated in  FIGS. 3A and 4A , the toner collection container  70  further includes a leveling member  79 . The leveling member  79  is a movable member such as a screw or a paddle made of a resin or a metal, such as polypropylene, having high strength and processability. The leveling member  79  particularly includes a rotational shaft  79 S, a paddle  79 P, a right-handed screw  79 R, and a left-handed screw  79 L. The rotational shaft  79 S penetrates the housing  72  in the longitudinal direction at a position slightly lower than the single color toner receiving ports  78 Y to  78 K, and is supported by both end surfaces in the longitudinal direction of the housing  72  in a manner rotatable around a center axis of its own. Inside the printer  130 , one end  79 E of the rotational shaft  79 S receives torque from a motor inside the printer  130 , and the rotational shaft  79 S is rotated around the center axis of its own by this torque. The paddle  79 P is a rectangular plate attached to a part included in an outer peripheral surface of the rotational shaft  79 S and positioned substantially equal to the C toner receiving port  78 C in the axial direction thereof, and has a plate surface radially expanding around the rotational shaft  79 S. The right-handed screw  79 R is a spiral-shaped blade extending in a manner winding clockwise on the outer peripheral surface of the rotational shaft  79 S, and the left-handed screw  79 L is a spiral-shaped blade extending in a manner winding anticlockwise on the outer peripheral surface of the rotational shaft  79 S. The right-handed screw  79 R is positioned on a side provided with the Y, M, C toner receiving ports  78 Y,  78 M,  78 C and the left-handed screw  79 L is positioned on a side provided with the K toner receiving port  78 K with respect to the paddle  79 P. With rotation of the rotational shaft  79 S, all of the paddle  79 P, right-handed screw  79 R, and left-handed screw  79 L are rotated around the rotational shaft  79 S in the same direction. With this rotation, the two screws  79 R and  79 L level, toward the paddle  79 P, a top portion of mountain-like waste toner raised under the waste toner receiving ports  78 I to  78 K, and then the paddle  79 P levels, toward the rear face of the housing  72 , the mountain-like waste toner having been leveled by the screws  79 R and  79 L and gathered immediately below the paddle. With this action, the mountain-like waste toner is leveled, and a surface of the waste toner is leveled in the entire hollow  72 H of the housing  72 . As a result, the waste toner is actually stored in a region positioned lower than the leveling member  79  inside the hollow of the housing  72 , namely, a region STR close to the bottom surface  72 B of the housing  72  than the leveling member  79  is (refer to a hatched part illustrated in  FIGS. 4A and 4B ). Note that this region STR will be referred to as “storing region” in the following. 
     Bay Window for Full-State Detection 
     As illustrated in  FIG. 3B , a bay window  72 W protrudes rearward from the rear wall  72 R of the housing  72 . The bay window  72 W is a hollow box-shaped protrusion, and a hollow inside thereof communicates with the hollow of the housing  72 . The bay window  72 W is positioned particularly below the C toner receiving port  78 C at a height substantially same as that of the paddle  79 P. With this structure, when the paddle  79 P is rotated, the waste toner flows into the inside of the bay window  72 W. The bay window  72 W has high transparency for particularly an infrared ray or visible light. Inside the printer  130 , the bay window  72 W faces a toner sensor PTS provided in the printer  130 . The toner sensor PTS is, for example, a transmissive photosensor, and includes a light emitter and a light receiver in each of two arms protruding in a U shape. The bay window  72 W is arranged on a light ray from the light emitter to the light receiver between these arms. While the inside of the bay window  72 W is empty, the infrared ray or visible light emitted from the light emitter passes through the bay window  72 W and is detected by the light receiver. When a certain amount or more of waste toner is stored inside the bay window  72 W, the waste toner interrupts the infrared ray or visible light emitted from the light emitter, and hinders detection by the light receiver. When the storing region STR of the housing  72  is full of the waste toner, the certain amount is equal to an amount of waste toner that has flown into the inside of the bay window  72 W. Therefore, whether the storing region STR of the housing  72  is full with waste toner can be determined by whether the infrared ray or visible light from the light emitter is detected by the light receiver. 
     Strength and Rigidity of Toner Collection Container 
     A manufacturing process of the toner collection container  70  includes, for example, following steps. First, the front wall  72 F and the rear wall  72 R of the housing  72  are formed separately from thermoplastic resins by a unit of injection molding or the like. In this step, the ducts  71 Y to  71 K are integrally molded with the front wall  72 F, and the vertical walls  76 Y to  76 K are integrally molded with the rear wall  72 R. Next, the front wall  72 F and the rear wall  72 R are welded to each other with the leveling member  79  incorporated therebetween. Particularly, the ducts  71 Y to  71 K are welded to the rear wall  72 R while penetrating the storing region STR in the hollow of the housing  72 . With this structure, the ducts  71 Y to  71 K serve as “beams” in the structure of the housing  72 , and therefore, the storing region STR has strength higher than that in other parts of the housing  72 . Specifically, even in a case where a user mistakenly slips the container  70  out of the hand and drops the same on a floor at the time of replacing the toner collection container  70 , a powder pressure of waste toner caused by collision with the floor is prevented from being concentrated only on the inner surface of the housing  72  but is dispersed to the ducts  71 Y to  71 K. As a result, damage on the inner surface of the housing  72  caused by rapid concentration of the powder pressure is prevented. 
     Furthermore, the bay window  72 W is interposed between the two ducts  71 C and  71 K. Due to presence of these two ducts  71 C,  71 K, the vicinity of the bay window  72 W has rigidity higher than that in other parts of the housing  72  do. Specifically, even in a case where distribution of waste toner stored inside the housing  72  is non-uniform, the ducts  71 Y to  71 K prevent deformation of the housing  72  caused by the weight of the waste toner, and particularly, the vicinity of the bay window  72 W is prevented from being deflected in the longitudinal direction of the housing  72 . As a result, inside the printer  130 , the position of the bay window  72 W with respect to the toner sensor PTS is kept correctly on the light ray from the light emitter to the light receiver. Thus, a full-state detection error caused by the toner sensor PTS is surely kept within the allowable range. 
     Advantages of Embodiment 
     As described above, the toner collection container  70  according to the embodiment of the present invention has the housing  72  incorporated between the air inlet port  80  and the image former  20  of the printer  130 . The four ducts  71 Y to  71 K penetrate the storing region STR inside the housing  72  from the front wall  72 F to the rear wall  72 R of the housing  72 , and guide the external air flowing from the air inlet port  80  to the side where the image former  20  is positioned. Since the ducts  71 Y to  71 K function as the “beams” in the structure of the housing  72 , the housing  72  has high strength and rigidity regardless of strength and rigidity of a material thereof. Thus, the toner collection container  70  prevents damage by impact in a fall and deformation caused by the weight of the waste toner regardless of the strength and rigidity of the material, and does not hinder an airflow inside the printer  130  even while keeping a sufficiently large storable amount of waste toner. 
     MODIFIED EXAMPLES 
     (A) The image forming device  100  illustrated in  FIGS. 1A and 1B  is a color print compliant MFP. The image forming device according to the embodiment of the present invention may also be a monochrome MFP dedicated to monochrome or a single function machine such as a printer, a copier, or a facsimile machine. 
     (B) An outer shape of the housing  72  of the toner collection container  70  illustrated in  FIGS. 3A, 3B, 4A , and  4 B is merely an example, and may be changed in accordance with a shape of a surrounding member inside the printer  130 , or may be changed for user friendliness. Similarly, a duct shape is not limited to the cylindrical shapes of the ducts  71 Y to  71 K in which radii are uniform in the axial direction, and may be a shape having an elliptical or polygonal cross-section. As far as a duct has a structure penetrating the storing region, strength of the storing region can be kept sufficiently high without hindering an airflow inside the printer  130  regardless of the details of the outer shape of the housing and the details of the duct shape. 
     (C) In  FIGS. 3A, 3B, 4A, and 4B , the duct  71 K forming a ventilation passage to the image forming unit  21 K for the color K has the cross-sectional area larger than the cross-sectional areas of other ducts  71 Y to  71 C. Thus, the cross-sectional areas may be different between the four ducts  71 Y to  71 K. 
       FIG. 5A  is a perspective view illustrating an external view from a position where a front face of a first modified example of a toner collection container  170  according to the embodiment of the present invention is visible, and  FIG. 5B  is a perspective view illustrating an external view from a position where a rear face thereof is visible. In  FIGS. 5A and 5B , the front and rear faces of the container  170  are partially removed and an internal structure of the container  170  is visible. The container  170  of the first modified example differs from the container  70  of the above-described embodiment in a position of the bay window for full-state detection, a cross-sectional area of each duct, and a structure of the leveling member. Since other elements are similar, the bay window, duct, and leveling member will be described below, and as for other elements, the description of the above embodiment will be used. 
     As illustrated in  FIG. 5B , a bay window  172 W protrudes rearward from the rear wall  72 R of the housing  72 . The bay window  172 W has a structure in which a height from the bottom surface  72 B of the housing  72  is similar to the bay window  72 W illustrated in  FIG. 3B . However, a position of the bay window  172 W in the longitudinal direction of the housing  72  is positioned between the color toner receiving port  78 I and the K toner receiving port  78 K, and is particularly close to the end face in the longitudinal direction of the housing  72 . Since a paddle  179 P is arranged in front of this bay window  172 W, a leveling member  179  has a longer right-handed screw  179 R and a shorter left-handed screw  179 L than those of the leveling member  79  illustrated in  FIG. 4A . In a case where rigidity in the vicinity of the end face in the longitudinal direction of the housing  72  is already sufficiently high because the bay window  172 W is located close thereto, a cross-sectional area of a duct  171 K located closest to the bay window  172 W may be designed to be smaller than cross-sectional areas of other ducts  71 Y to  71 C. The smaller a cross-sectional area of a duct is, the more increased a storable amount of waste toner is in the surrounding region. Additionally, since a mountain-like shape of waste toner stored in the surrounding region is hardly distorted, a correspondence relation between the amount of waste toner stored inside the bay window  172 W and the amount of waste toner inside the storing region STR is hardly varied, and a full-state detection error by the toner sensor PTS hardly exceeds the allowable range. 
     (D) In  FIGS. 3A, 3B, 4A, and 4B , the guide passages (vertical walls)  76 Y to  76 K of the toner collection container  70  are perpendicular to the longitudinal direction of the housing  72 . With this structure, airflows having passed through the ducts  71 Y to  71 K are released from the same positions in the longitudinal direction of the housing  72  to the space surrounded by the intermediate transfer belt  23  and to the image forming units  21 Y to  21 K. Not limited thereto, the guide passage can be freely modified in accordance with a position where an airflow is to be released. 
       FIG. 6A  is a perspective view illustrating an external view from a position where a front face of a second modified example of a toner collection container  270  according to the embodiment of the present invention is visible, and  FIG. 6B  is a perspective view illustrating an external view from a position where a rear face thereof is visible. In  FIG. 6A , an entire front face of the container  270  is removed, and an internal structure of the container  270  is visible. The container  270  of the second modified example differs from the container  70  of the above-described embodiment in that: the cross-sectional areas of the four ducts  71 Y to  71 K are equal; and guide passages (vertical walls)  276 Y to  276 K have different shapes. Since other elements are similar, the guide passages (vertical walls) will be described below, and as for other elements, the description of the above embodiment will be used. 
     As illustrated in  FIG. 6B , four vertical holes  275 Y to  275 K are formed in the rear wall  72 R of the housing  72 . Similar to the vertical holes  75 Y to  75 K illustrated in  FIG. 3B , each of lower ends of the vertical holes  275 Y to  275 K faces a different image forming unit out of the image forming units  21 Y to  21 K, and upper ends thereof face the space surrounded by the intermediate transfer belt  23 . However, different from the vertical holes  75 Y to  75 K illustrated in  FIG. 3B , each of the vertical holes  275 Y to  275 K has an intermediate part inclined with respect to a height direction of the housing  72 , and each of the intermediate portions connects each of the upper ends to each of the lower ends. With this structure, the respective lower ends of the vertical holes  275 Y to  275 K are positioned at positions substantially equal to the single color toner receiving ports  78 Y to  78 K but the respective upper ends are positioned in middle positions between the single color toner receiving ports  78 Y to  78 K in the longitudinal direction of the housing  72 . 
     As illustrated in  FIG. 6A , vertical walls  276 Y to  276 K extend upward along the inner side of the rear wall  72 R of the housing  72  from respective connecting portions between the ducts  71 Y to  71 K and the lower ends of the vertical holes  275 Y to  275 K, and block the vertical holes  275 Y to  275 K from the inside. On the other hand, thin resin plate-like members  277 Y to  277 K each made of, for example, a resin block respective regions between the upper ends and the lower ends from the outside of the vertical holes  275 Y to  275 K. With this structure, a gap between each of the vertical walls  276 Y to  276 K and each of the plate-like members  277 Y to  277 K, namely, a guide passage guides an airflow from each of the ducts  71 Y to  71 K to each of the upper ends of the vertical holes  275 Y to  275 K. Since the intermediate parts of the guide passages (vertical walls)  276 Y to  276 K are inclined with respect to the height direction of the housing  72 , positions from which airflows having passed through the ducts  71 Y to  71 K are released to the space surrounded by the intermediate transfer belt  23  and to the image forming units  21 Y to  21 K are different in the longitudinal direction of the housing  72 . These positions can be adjusted in accordance with arrangement of the motor and the control circuit thereof in the deeper side of the space surrounded by the intermediate transfer belt  23  so as to keep a high cooling air effect for the motor and the control circuit thereof. 
     (E) In  FIGS. 3A, 3B, 4A, and 4B , the ducts  71 Y to  71 K connect the round holes  74 Y to  74 K on the front face of the toner collection container  70  to the rear vertical holes  75 Y to  75 K in a one-to-one relation. With this structure, the external air flowing into the different round holes is released separately from the different vertical holes  75 Y- 75 K without being joined. Not limited thereto, the housing  72  may include a structure in which airflows having passed through the different ducts are joined. 
       FIG. 7A  is a perspective view illustrating an external view from a position where a front face of a third modified example of a toner collection container  370  according to the embodiment of the present invention is visible, and  FIG. 7B  is a perspective view illustrating an external view from a position where a rear face thereof is visible. In  FIG. 7A , the entire front face of the container  370  and the leveling member are removed, and a structure of the rear wall  72 R of the housing  72  is visible. The container  370  of the third modified example differs from the container  70  of the above embodiment in that: sizes of the four vertical holes  75 Y to  75 K are equal; and the rear wall  72 R of the housing  72  includes communication passage to provide communication between different guide passages. Since other elements are similar, the communication passages will be described below, and as for other elements, the description of the above embodiment will be used. 
     As illustrated in  FIG. 7B , cutouts  75 KC,  75 CM, and  75 MY extend between the vertical holes  75 K to  75 Y on the rear wall  72 R of the housing  72 . These cutouts  75 KC to  75 MY are arranged in a straight line that connects, in an oblique direction relative to the longitudinal direction of the housing  72 , regions between the vicinity of the upper end of the vertical hole  75 K closest to the K toner receiving port  78 K and the lower end of the farthest vertical hole  75 Y, and the cutouts have a constant width in entire parts thereof. As illustrated in  FIG. 7A , an inner side of each of the cutouts  75 KC to  75 MY is blocked by each of expansion walls  76 YM,  76 MC, and  76 CK that respectively connect regions between the vertical walls  76 Y to  76 K. On the other hand, the outer side of each of the cutouts  75 KC to  75 MY is blocked by each of thin plate-like members  77 KC,  77 CM, and  77 MY each made of a resin, for example. With this structure, respective gaps between the expansion walls  76 CK to  76 YM and the plate-like members  77 KC to  77 MY function as communication passages to provide communication between different guide passages. Particularly, since each communication passage is inclined with to the longitudinal direction of the housing  72 , an airflow is branched to an adjacent guide passage (vertical wall)  76 M from the lower end of the vertical hole  75 Y farthest from the K toner receiving port  78 K, subsequently the airflow is branched to an adjacent guide passage (vertical wall)  76 C from the guide passage (vertical wall)  76 M, and then the airflow is branched further to an adjacent guide passage (vertical wall)  76 K from the guide passage (vertical wall)  76 C. Although not illustrated in  FIGS. 7A and 7B , valves that further branch, to the communication passages from the ducts  71 Y to  71 K, the airflows having been branched to the guide passages (vertical walls)  76 Y to  76 K from the ducts  71 Y to  71 K may be installed at respective intersections between the communication passages and the guide passages (vertical walls)  76 Y to  76 K. Thus, branched airflows from other three guide passages (vertical walls)  76 Y to  76 C are added to the airflow flowing through the guide passage (vertical wall)  76 K closest to the K toner receiving port  78 K. With this structure, a ratio of a flow rate of the air that flows through the duct is  71 K, out of external air introduced by the fan  81 , is larger than a ratio of a flow rate of the air flowing through each of other ducts  71 Y to  71 C. As a result, more airflows flow into the image forming unit  21 K for the color K, which is most frequently used, than airflows flowing into other image forming units  21 Y to  21 C, and therefore, the ventilation effect such as the air cooling effect is kept high. 
     (F) In  FIGS. 3A, 3B, 4A, and 4B , the ducts  71 Y to  71 K penetrate the storing region STR in the hollow of the toner collection container  70 , and connect the round holes  74 Y to  74 K on the front face to the vertical holes  75 Y to  75 K on the rear face. With this structure, the ducts  71 Y to  71 K serve as the “beams” in the structure of the housing  72  of the container  70 , and therefore, the storing region STR has strength higher than that in other parts of the housing  72 . Furthermore, a duct may also be formed on an outer surface of the housing, particularly, on a part included in the bottom surface thereof and recessed toward the storing region. Due to presence of this duct, the bottom surface has strength higher than that in other parts of the housing, and therefore, even in a case where the container is subjected to direct impact from a floor when dropped on the floor, and the bottom surface is prevented from being damaged such as dented or cracked. 
       FIG. 8A  is a perspective view illustrating an external view of the printer  130  in which a fourth modified example of the toner collection container  470  according to the embodiment of the present invention is incorporated, and  FIG. 8B  is a schematic vertical cross-sectional view of the printer  130  taken along a line b-b illustrated in  FIG. 8A . In  FIG. 8A , the front doors  131  to  133  of the body of the MFP  100  are opened, and therefore, the container  470  of the fourth modified example is visible from the outside. This container  470  differs from the container  70  of the above-described embodiment in that a recess on the bottom surface constitutes a duct. Since other elements are similar, the duct will be described below, and as for other elements, the description of the above embodiment will be used. 
     With rotation of the fan  81 , the external air is introduced into the inside of the body from the air inlet port  80 , and the air inside the body is exhausted to the outside from the air outlet port  82 . With this structure, airflows directed from the air inlet port  80  toward the air outlet port  82  are generated in a space inside the body, as indicated by one-dot chain lines in  FIG. 8B . These airflows mainly pass through the space surrounded by the intermediate transfer belt  23  and the gap between the exposure unit  27  and the image forming units  21 Y to  21 K, and flow into the drive unit  90 . Since the airflow thus flows from the air inlet port  80  to the air outlet port  82 , ozone generated due to discharge at the electric charger  26  is released to the external air, and the motor and the control circuit included in the drive unit  90  and the exposure unit  27  are cooled. 
     As illustrated in  FIGS. 8A and 8B , the toner collection container  470  is incorporated in the gap between the air inlet port  80  and the image former  20 . The gap between the container  470  and members surrounding the same, such as the replenishing unit  60 , is narrow. However, this container  470  has three ducts  71 YM,  71 MC, and  71 CK on the bottom surface, and has an end  71 H in the longitudinal direction of the bottom surface recessed in a round shape. All of the ducts  71 YM to  71 CK are portions included in the bottom surface of the container  470  and recessed toward the storing region, and extend from the side where the air inlet port  80  is positioned to the side where the image former  20  is positioned. With this structure, each of the ducts  71 YM to  71 CK guides, in cooperation with the end  71 H of the bottom surface, the external air flowing from the air inlet port  80  to the space surrounded by the intermediate transfer belt  23  and to the gap between the exposure unit  27  and the image forming units  21 Y to  21 K. Since the ducts  71 YM to  71 CK thus function as ventilation passages, a large amount of the external air flowing from the air inlet port  80  into the drive unit  90  through the image former  20  is secured despite a fact that the gap around the toner collection container  470  is narrow. As a result, even in a case where the toner collection container  470  blocks a large part of the space inside the front door  133 , both of the effect of removing ozone from the image former  20  by ventilation and the effect of cooling the drive unit  90  and the exposure unit  27  are sufficiently high. 
       FIG. 9A  is a perspective view illustrating an external view from a position where a front face of the toner collection container  470  of the fourth modified example is visible, and  FIG. 9B  is a perspective view illustrating an external view from a position where a rear face thereof is visible. In  FIG. 9A , the entire front face of the container  470  is removed, and an internal structure of the container  470  is visible.  FIG. 10A  is a front view of the container  470  illustrated in  FIG. 9A , and  FIG. 10B  is a rear view of the container  470  illustrated in  FIG. 9B . As illustrated in  FIGS. 9A, 9B, 10A, and 10B , all of ducts  71 YM to  71 CK are hollow grooves provided at a bottom surface  472 B of a housing  472  of the container  470 , and extend perpendicular to the longitudinal direction of the housing  472 , and the grooves each have a uniform radius in an entire part thereof. The ducts  71 YM to  71 CK are respectively positioned in the middle positions between the single color toner receiving ports  78 Y to  78 K in the longitudinal direction of the housing  472 , and guide the external air introduced by the fan  81  to the image forming units  21 Y to  21 K, respectively. In  FIGS. 9A, 9B, 10A, and 10B , all of the ducts  71 YM to  71 CK have equal cross-sectional areas. However, similar to the ducts  71 Y to  71 K according to the above-described embodiment, the cross-sectional areas may be different in accordance with a difference between required ventilation amounts in the image forming units  21 Y to  21 K. 
     As illustrated in  FIGS. 9B and 10B , three vertical holes  75 KC,  75 CM, and  75 MY are opened on a rear wall  472 R of the housing  472 . Each of the vertical holes  75 KC to  75 MY has a rectangle shape long in a short side direction of the rear wall  472 R, and lower ends thereof are connected to the ducts  71 YM to  71 CK. On the other hand, as illustrated in  FIGS. 9A and 10A , vertical walls  76 YM,  76 MC, and  76 CK block inner sides of the vertical holes  75 MY,  75 CM, and  75 KC, and isolate a hollow  472 H of the housing  472  from the outside, and also secure gaps inside the respective vertical holes. A region between an upper end and a lower end of each of the vertical holes  75 YM to  75 CK are blocked from the outside by each of thin plate-like members  77 YM,  77 MC, and  77 CK made of a resin, for example. With this structure, respective gaps between the vertical walls  76 YM to  76 CK and the plate-like members  77 YM to  77 CK function as guide passages to guide airflows flown from the fan  81  to the upper ends of the vertical holes  75 YM to  75 CK from the ducts  71 YM to  71 CK, respectively. Since these upper ends face the space surrounded by the intermediate transfer belt  23 , the airflows having passed through the ducts  71 YM to  71 CK are also branched into the guide passages (vertical walls)  76 YM to  76 CK, and released to the space surrounded by the intermediate transfer belt  23 . With this structure, the air cooling effect for the motor of the drive unit  90  and the like can be highly maintained. 
     In a manufacturing process of the toner collection container  470 , the ducts  71 YM to  71 CK are integrally molded with the housing  472 . The bottom surface  472 B has elasticity higher than that in other surfaces of the housing  472  because of the presence of the ducts  71 YM to  71 CK. Specifically, even in a case where the bottom surface  472 B directly collides with a floor when a user mistakenly slips the container  470  out of the hand and drops the same on the floor at the time of replacing the container  470 , impact force from the floor is absorbed by elastic change in the recesses of the ducts  71 YM to the  71 CK. As a result, the bottom surface  472 B is prevented from being damaged, such as dented or cracked, even though direct impact is received from the floor. 
     (G) In  FIGS. 3A, 3B, 4A, and 4B , the housing  72  of the toner collection container  70  has the length in one direction longer than that in another direction, and the ducts  71 Y to  71 K are arranged orthogonal to the longitudinal direction of the housing  72 . The reason is that: as illustrated in  FIGS. 2A and 2B , the air inlet port  80  and the fan  81  of the MFP  100  are positioned, with respect to the housing  72 , in a direction orthogonal to the longitudinal direction of the housing  72 . Different from this, in a case where an air inlet port and a fan of an MFP are positioned, with respect to a toner collection container, in a longitudinal direction of a housing thereof, a duct may extend in the longitudinal direction thereof. 
       FIG. 11  is a perspective view illustrating an external view of the printer  130  in which a fifth modified example of a toner collection container  570  according to the embodiment of the present invention is incorporated. In  FIG. 11 , the front doors  131  to  133  of the body of the MFP  100  are opened, and therefore, the container  570  of the fifth modified example is visible from the outside. This container  570  differs from the container  70  of the above embodiment in a structure of a duct. Since other elements are similar, the duct will be described below, and as for other elements, the description of the above embodiment will be used. 
     An air inlet port  180  is a hole opened like a mesh on a side of the front door  133  out of side surfaces of the body of the MFP  100 , and provides communication between an inner space of the body and the outside thereof. A fan  181  is installed inside the side surface of the body, particularly, in a deeper side of the air inlet port  180 . With rotation of the fan  181 , external air is introduced into the inside of the body from the air inlet port  180 . On the other hand, air inside the body is exhausted to the outside from the air outlet port  82  positioned on the rear face of the body illustrated in  FIGS. 2A and 2B . With this structure, airflows directed from the air inlet port  180  to the air outlet port  82  are generated in a space inside the body. Similar to the airflows illustrated in  FIG. 2B , these airflows mainly pass through the space surrounded by the intermediate transfer belt  23  and the gap between the exposure unit  27  and the image forming units  21 Y to  21 K in the image former  20 , and flow into the drive unit  90 . The airflow having passed through the drive unit  90  escapes from the air outlet port  82  to the external air. Since the airflow thus flows from the air inlet port  180  to the air outlet port  82 , ozone generated due to discharge at the electric charger  26  is released to the external air, and the motor and the control circuit included in the drive unit  90  and the exposure unit  27  are cooled. 
     As illustrated in  FIG. 11 , the toner collection container  570  of the fifth modified example is incorporated in a gap between the front door  133  of the body and the image former  20 . The gap between the container  570  and members surrounding the same, such as the replenishing unit  60 , is narrow. However, one duct  571  extends in the longitudinal direction of the housing on the rear face of the container  570 . The duct  571  includes openings on both side surfaces and the rear face of the container  570 , and guides external air flowing from the air inlet port  180  from an opening positioned on the side surfaces of the container  570  to an opening positioned on the rear face, thereby moving the external air to the space surrounded by the intermediate transfer belt  23 . Since the duct  571  thus functions as a ventilation passage, a large amount of the external air flowing into the drive unit  90  from the air inlet port  180  through the image former  20  is secured despite a fact that the gap around the container  570  is narrow. As a result, even in a case where the toner collection container  570  blocks a large part of the space inside the front door  133 , both of the effect of removing ozone from the image former  20  by ventilation and the effect of cooling the drive unit  90  and the exposure unit  27  are sufficiently high. 
       FIG. 12A  is a perspective view illustrating an external view from a position where a front face of the toner collection container  570  of the fifth modified example is visible, and  FIG. 12B  is a perspective view illustrating an external view from a position where a rear face thereof is visible. In  FIG. 12A , the entire front face of the container  570  is removed, and an internal structure of the container  570  is visible. As illustrated in  FIGS. 12A and 12B , the duct  571  is a rectangular groove extending in a longitudinal direction of a housing  572  in a region included in a rear wall  572 R of the housing  572  of the container  570  and facing the storing region STR, and has a width and a depth which are uniform in an entire part thereof. Both ends of the duct  571  are connected to rectangular holes  571 E opened on both side surfaces of the housing  572 . The duct  571  is further blocked by a thin plate-like member  577  made of a resin, for example, from the rear face side of the housing  572 . With this structure, an airflow sent from the fan  181  flows into the duct  571  from the hole  571 E on one side surface of the housing  572 , passes through the duct  571 , and is flows out from the other hole on the opposite side surface of the housing  572 . 
     As illustrated in  FIG. 12B , four vertical holes  575 Y,  575 M,  575 C, and  575 K are opened on the rear wall  572 R of the housing  572 . Each of the vertical holes  575 Y to  575 K has rectangle shape having a long length in a short side direction of the rear wall  572 R, and has a lower end connected to the duct  571 . On the other hand, as illustrated in  FIG. 12A , vertical walls  576 Y,  576 M,  576 C, and  576 K block the inner side of the vertical holes  575 Y to  575 K, and isolate a hollow  572 H of the housing  572  from the outside, and also secure gaps in the respective vertical holes. A region between an upper end and a lower end of each of the vertical holes  575 Y to  575 K is blocked from the outside by each of thin plate-like members  577 Y,  577 M,  577 C, and  577 K each made of a resin, for example. With this structure, respective gaps between the vertical walls  576 Y to  576 K and the plate-like members  577 Y to  577 K function as guide passages to guide the airflow passing through the duct  571  to the upper ends of the vertical holes  575 Y to  575 K. Since the upper ends thereof face the space surrounded by the intermediate transfer belt  23 , the airflow passing through the duct  571  is also branched into the guide passages (vertical walls)  576 Y to  576 K and the plate-like members  577 Y to  577 K, and released to the space surrounded by the intermediate transfer belt  23 . With this structure, the air cooling effect for the motor of the drive unit  90  and the like can be highly maintained. 
     In a manufacturing process of the toner collection container  570 , the duct  571  is integrally molded with the housing  572 . Due to the presence of the duct  571 , the rear wall  572 R of the housing  572  has rigidity higher than that in other surfaces of the housing  572 . In other words, the duct  571  prevents deflection of the rear wall  572 R in the longitudinal direction of the housing  572  caused by a weight of waste toner. As a result, inside the printer  130 , the position of the bay window  72 W with respect to the toner sensor PTS is kept correctly on the light ray from the light emitter to the light receiver. Thus, a detection error by the toner sensor PTS is surely kept within the allowable range. 
     The rear wall  572 R of the housing  572  illustrated in  FIG. 12B  further includes an actuator  572 W. For example, the actuator  572 W is a box-shaped protrusion similar to the bay window  72 W. Inside the printer  130 , the actuator  572 W contacts a sensor BXS to detect the toner collection container provided in the printer  130 . The sensor BXS is, for example, a contact type mechanical switch or a strain gauge type pressure sensor, and detects attachment of the toner collection container  570  on the basis of a state change from OFF to ON of a switch or stress increase caused by contact of the actuator  572 W. 
     The vicinity of the actuator  572 W has rigidity higher than that in other surfaces of the housing  572  due to the presence of the duct  571  in a manner similar to the vicinity of the bay window  72 W. In other words, the duct  571  prevents deflection of the rear wall  572 R in the longitudinal direction of the housing  572  caused by the weight of waste toner. As a result, inside the printer  130 , the actuator  572 W contacts the sensor BXS at the correct position. Thus, a detection error of attachment of the housing  572  by the sensor BXS is surely maintained within the allowable range. 
     The present invention relates to a toner collection container provided in an image forming device, and a member penetrating a storing region in the housing or a duct formed as a recess at a bottom surface of the housing is formed in the housing of the container as described above. Thus, the present invention is obviously industrially applicable. 
     Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims.