Patent Publication Number: US-9846393-B2

Title: Waste toner collecting device and image forming apparatus including the same

Description:
INCORPORATION BY REFERENCE 
     This application is based on and claims the benefit of priority from Japanese Patent application No. 2016-061371 filed on Mar. 25, 2016, which is incorporated by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to a waste toner collecting device which collects a waste toner including a toner removed by a cleaning device and a scattered toner, and an image forming apparatus including the waste toner collecting device. 
     In an electrophotographic type image forming apparatus, such as a copying machine, a printer and a facsimile, a powder developer is mainly used. A latent image formed on an image carrier such as a photosensitive drum is visualized into a toner image with the developer (a toner) supplied from a developing device. The toner image is transferred on a sheet directly or via an image carrier such as an intermediate transferring belt, and then fixed on the sheet. The toner remained on the image carrier after the transferring is removed by a cleaning device, conveyed to a waste toner collection container by a conveying member such as a conveying screw to be collected. 
     On the other hand, when the latent image is visualized into the toner image by the developing device, some of the toner may be scattered, leaked out from the developing device and contaminate an inside of the image forming apparatus. Thereby, the image forming apparatus is sometimes provided with a floating toner collection container. In such a floating toner collection container, air including the scattered toner in the developing device (hereinafter, called as a floating toner) is sucked by a suction device, the floating toner is separated from the air and then collected. 
     However, in many cases, the floating toner collection container is provided separately from the waste toner collection container in which the waste toner removed from the image carrier by the cleaning device is collected. Thereby, if each container is filled with the collected toner, it is necessary to replace the floating toner collection container and the waste toner collection container separately, and a replacement work may be performed frequently. In addition, it is necessary to secure space where the floating toner collection container and the waste toner collection container are disposed, and thus the image forming apparatus may become large in size. 
     To solve the above problems, a suction path through which the floating toner is sucked may be provided in the waste toner collection container. In this case, although a space saving of the image forming apparatus becomes possible, because the toner collected in the waste toner collection container is also sucked through the suction path, suction force of the floating toner is lowered, and the floating toner cannot be efficiently removed. 
     SUMMARY 
     In accordance with an aspect of the present disclosure, a waste toner collecting device includes an intermediate collection box, a waste toner collection container, a conveying path, a conveying screw, an exhaust path and a floating toner collection chamber. The intermediate collection box stores a toner removed from an image carrier by a cleaning device. In the waste toner collection container, the toner stored in the intermediate collection box is collected. The conveying path is formed on a bottom face of the intermediate collection box. The conveying screw is supported in the conveying path so as to be rotatable in a normal direction and in a reverse direction. The conveying screw conveys the stored toner toward the waste toner collection container by rotating in the normal direction. Through the exhaust path, air containing a floating toner is sucked and passed. The floating toner collection chamber is provided on a part of the exhaust path and stores the floating toner separated from the air. The floating toner collection chamber is provided in the intermediate collection box. The floating toner collection chamber has a discharge opening and a discharge door. The discharge opening is opened to an inside of the intermediate collection box. The discharge door is interfered with the conveying screw as the conveying screw is rotated. The discharge door is turned between a storage position where the discharge opening is closed and a discharge position where the discharge opening is opened. Rotation of the conveying screw in the normal direction turns the discharge door into the storage position. Rotation of the conveying screw in the reverse direction turns the discharge door into the discharge position so that the floating toner stored in the floating toner collection chamber is discharged in the conveying path through the discharge opening. 
     In accordance with an aspect of the present disclosure, an image forming apparatus includes a developing device, a cleaning device and the above described waste toner collecting device. The developing device forms a toner image on an image carrier. The cleaning device removes the toner on the image carrier. 
     The above and other objects, features, and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present disclosure is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view showing a structure of an image forming apparatus according to an embodiment of the present disclosure. 
         FIG. 2  is a front view showing an image forming part of the image forming apparatus according to the embodiment of the present disclosure. 
         FIG. 3  is a front sectional view showing a structure of a developing device of the image forming apparatus according to the embodiment of the present disclosure. 
         FIG. 4  is a front side perspective view showing a waste toner collecting device according to an embodiment of the present disclosure. 
         FIG. 5  is a front side perspective view showing a floating toner collection chamber in the waste toner collecting device according to the embodiment of the present disclosure. 
         FIG. 6  is a front side perspective view showing an inside of the floating toner collection chamber in the waste toner collecting device according to the embodiment of the present disclosure. 
         FIG. 7  is a rear side perspective view showing the waste toner collecting chamber according to the embodiment of the present disclosure. 
         FIG. 8  is a sectional perspective view showing the floating toner collection chamber of which a discharge opening is closed with a discharge door, in the waste toner collecting device according to the embodiment of the present disclosure. 
         FIG. 9  is a sectional perspective view showing the floating toner collection chamber of which the discharge opening is opened with the discharge door, in the waste toner collecting device according to the embodiment of the present disclosure. 
         FIG. 10  is a front view showing a protruding piece and a spiral blade, in the waste toner collecting device according to the embodiment of the present disclosure. 
         FIG. 11A  is a side view showing the discharge door turned into a storage position, in the waste toner collecting device according to the embodiment of the present disclosure. 
         FIG. 11B  is a side view showing the discharge door turned into a discharge position, in the waste toner collecting device according to the embodiment of the present disclosure. 
         FIG. 12A  is a front view showing the spiral blade coming into contact with an inclined edge of the protruding piece, in the waste toner collecting device according to the embodiment of the present disclosure. 
         FIG. 12B  is a front view showing the spiral blade coming into contact with a tip edge of the protruding piece, in the waste toner collecting device according to the embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, with reference to figures, a waste toner collecting device  40  and an image forming apparatus  100  according to an embodiment of the present disclosure will be described. 
     With reference to  FIGS. 1 and 2 , the image forming apparatus  100  according to an embodiment of the present disclosure will be described.  FIG. 1  is a front view showing a structure of the image forming apparatus  100  and  FIG. 2  is a sectional view showing an image forming part Pa. The image forming apparatus  100  of the embodiment is a quadruple tandem type color printer including four image forming parts Pa, Pb, Pc and Pd which are adjacently arranged and form a full color image. The four image forming parts Pa, Pb, Pc and Pd respectively correspond to four different colors (magenta, cyan, yellow and black). In the following description, a front side of a paper plan of  FIG. 1  shows a front side of the image forming apparatus  100 , and left and right directions are based on a direction in which the image forming apparatus  100  is seen from the front side. Fr, Rr, L and R in each figure respectively show a front side, a rear side, a left side and a right side. 
     In an apparatus main body of the image forming apparatus  100 , the four image forming parts Pa to Pd are adjacently arranged in the order from the right side of  FIG. 1 . These image forming parts Pa to Pd sequentially form images of magenta, cyan, yellow and black by a charging process, an exposing process, a developing process and a transferring process. 
     In these image forming parts Pa to Pd, photosensitive drums  1   a,    1   b,    1   c  and  1   d  are respectively provided so as to be rotatable in the counterclockwise direction in  FIG. 1 . The photosensitive drums  1   a  to  1   d  are image carries each of which carries a visible image (a toner image) of each color. Above the photosensitive drums  1   a  to  1   d,  an intermediate transferring belt  8  is bridged between a driven roller  10  and a driving roller  11 . The intermediate transferring belt  8  is an image carrier which carries a visible image (a toner image) formed by overlapping the visible image of each color. The intermediate transferring belt  8  rotates in the clockwise direction at the same linier velocity as that of the photosensitive drums la to ld. In an inner hollow space of the intermediate transferring belt  8 , first transferring rollers  6   a,    6   b,    6   c  and  6   d  are rotatably supported. The first transferring rollers  6   a  to  6   d  respectively oppose to the photosensitive drums  1   a  to  1   d  via the intermediate transferring belt  8 . On the left side of the driving roller  11 , a secondary transferring roller  9  is rotatably supported. The secondary transferring roller  9  opposes to the driving roller  11  via the intermediate transferring belt  8 . 
     On a downstream side of the secondary transferring roller  9  in a rotation direction of the intermediate transferring belt  8  (near the driven roller  10 ), a belt cleaning device  19  is disposed. The belt cleaning device  19  removes the toner and the others remained on a surface of the intermediate transferring belt  8 . The belt cleaning device  19  has a blade and a collection part. The blade comes into contact with the intermediate transferring belt  8  from a counter direction to the rotation direction of the intermediate transferring belt  8 . The toner removed by the blade is collected in the collection part. The tonner collected in the collection part is conveyed toward the front side of the image forming apparatus  100  by a collection spiral. On a front face of the collection part, a discharge opening through which the conveyed toner is discharged is formed. 
     A sheet P on which the toner image is to be transferred is stored in a sheet feeding cassette  16  provided in a lower portion of the apparatus main body. The sheet P is conveyed to the secondary transferring roller  9  via a feed roller  12   a  and a registration roller pair  12   b.    
     Next, the image forming parts Pa to Pd will be described. In the image forming parts Pa to Pd, charging devices  2   a,    2   b,    2   c  and  2   d,  developing devices  3   a,    3   b,    3   c  and  3   d  and drum cleaning devices  7   a,    7   b,    7   c  and  7   d  are respectively disposed around the photosensitive drums  1   a  to  1   d.  The charging devices  2   a  to  2   d  charge the photosensitive drums  1   a  to  1   d  respectively. The developing devices  3   a  to  3   d  develop latent images formed on the photosensitive drums  1   a  to  1   d  with the toner respectively. The drum cleaning devices  7   a  to  7   d  remove and collect the developer (the toner) remained on the photosensitive drums  1   a  to  1   d  respectively after the toner images are transferred. Below the image forming parts Pa to Pd, an exposing unit  5  is disposed. The exposing unit  5  performs exposing to the photosensitive drums  1   a  to  1   d  according to an image data. 
     Next, an image forming operation will be described. When the image data is input from a host apparatus such as a personal computer, the charging devices  2   a  to  2   d  respectively charge the surfaces of the photosensitive drums  1   a  to  1   d  uniformly, and then the exposing unit  5  performs the exposing to the photosensitive drums  1   a  to  1   d  according to the input image data to form latent images corresponding to the input image data on the photosensitive drums  1   a  to  1   d.  The latent images are developed by the developing devices  3   a  to  3   d  into toner images of corresponding colors. Then, by applying a predetermined transferring voltage between the first transferring rollers  6   a  to  6   d  and the photosensitive drums  1   a  to  1   d,  the toner images of magenta, cyan, yellow and black colors are first-transferred on the intermediate transferring belt  8 . After that, in order to prepare for formation of next new latent images on the photosensitive drums  1   a  to  1   d,  the toner remained on the surfaces of the photosensitive drums  1   a  to  1   d  are removed by the drum cleaning devices  7   a  to  7   d  respectively. If a ratio of the toner to the two component developer filled in each of the developing devices  3   a  to  3   d  is lower than a predetermined value by the image forming operation described later, the toner is supplied to the developing devices  3   a  to  3   d  from toner containers  4   a  to  4   d  respectively. 
     The toner images formed on the photosensitive drums  1   a  to  1   d  are sequentially transferred on the intermediate transferring belt  8  which rotates in coming into contact with the photosensitive drums  1   a  to  1   d.  Then, a full color toner image is secondary-transferred on the sheet P by the secondary transferring roller  9 . The full color toner image is heated and pressed at a fixing device  13  to be fixed on the sheet P. The sheet P on which the full color toner image has been fixed is ejected by an ejection roller pair  15  on the ejection tray  7 . 
     With reference to  FIG. 2 , the image forming part Pa described above will be described in detail. The image forming parts Pb to Pd each have the substantially same structure as the image forming part Pa, and their detail descriptions are omitted. Around the photosensitive drum  1   a,  the charging device  2   a,  the developing device  3   a,  the first transferring roller  6   a  and the cleaning device  7   a  described above are arranged along a rotation direction of the photosensitive drum  1   a  (the counterclockwise direction in  FIG. 2 ). 
     The charging device  2   a  has a charging roller  20  and a cleaning roller  21 . The charging roller  20  comes in contact with the surface of the photosensitive drum  1   a  and applies a charging voltage on photosensitive drum  1   a.  The cleaning roller  21  cleans the charging roller  20 . 
     The drum cleaning device  7   a  has a rubbing roller  22 , a cleaning blade  23  and a collection spiral  24 . The rubbing roller  22  comes in pressure contact with the photosensitive drum  1   a  at a predetermined pressure. 
     The cleaning blade  23  is supported on a downstream side of the contact portion of the rubbing roller  22  and the photosensitive drum  1   a  in the rotation direction of the photosensitive drum  1   a,  and comes in contact with the photosensitive drum  1   a  from a counter direction to the rotation direction of the photosensitive drum  1   a.    
     The collection spiral  24  conveys the toner removed from the surface of the photosensitive drum  1   a  by the rubbing roller  22  and the cleaning blade  23  to the front side of the image forming apparatus  100 . On a front face of the drum cleaning device  7   a,  a discharge opening through which the conveyed toner is discharged is formed. 
     Next, with reference to  FIG. 3 , the developing device  3   a  will be described.  FIG. 3  is a sectional view showing a vicinity around the developing device  3   a.    
     The developing device  3   a  has a development container  30  in which the two component developer containing a magnetic carrier and a toner (hereinafter, called as the developer) is contained. The development container  30  is divided by a partition wall  30   a  into an agitating/conveying chamber  31  and a supplying/conveying chamber  32 . In the agitating/conveying chamber  31  and the supplying/conveying chamber  32 , an agitating/conveying screw  33   a  and a supplying/conveying screw  33   b  are rotatably disposed respectively. The agitating/conveying screw  33   a  and the supplying/conveying screw  33   b  mix the toner supplied from the toner container  4   a  (refer to  FIG. 1 ) with the magnetic carrier, agitate them and charge the toner. 
     In the agitating/conveying chamber  31  and the supplying/conveying chamber  32 , the developer is agitated and conveyed by the agitating/conveying screw  33   a  and the supplying/conveying screw  33   b  in an axis direction of each screw (a perpendicular direction to the paper plan of  FIG. 3 ). The developer circulates between the agitating/conveying chamber  31  and the supplying/conveying chamber  32  through developer passing paths (not shown) formed at both end portion of the partition wall  30   a.    
     The development container  30  extends in the left upper oblique direction in  FIG. 3 . The development container  30  has an opening  30   b  formed at a portion opposing to the photosensitive drum  1   a.  In the development container  30 , a magnetic roller  34  and a developing roller  35  are disposed. The magnetic roller  34  is positioned opposite to the supplying/conveying screw  33   b  in the vertical direction. The developing roller  35  is positioned opposite to the magnetic roller  34  in the left upper oblique direction. A part of an outer circumferential face of the developing roller  35  is exposed through the opening  30   b  and opposes to the photosensitive drum  1   a.  The magnetic roller  34  and the developing roller  35  are rotated in the clockwise direction in  FIG. 3 . 
     On an upstream side of the opposing area R of the developing roller  35  and the magnetic roller  34  in a rotation direction of the magnetic roller  34 , a regulating blade  36  is attached along a length direction of the magnetic roller  34  (a perpendicular direction to the paper plan of  FIG. 3 ). Between a tip edge of the regulating blade  36  and an outer circumferential face of the magnetic roller  34 , a small gap is formed. 
     As described above, the developer is agitated while circulating between the agitating/conveying chamber  31  and the supplying/conveying chamber  32  in the development container by the agitating/conveying screw  33   a  and the supplying/conveying screw  33   b.  This charges the toner. The developer containing the charged toner is conveyed to the magnetic roller  34  by the supplying/conveying screw  33   b  to form a magnetic brush around the magnetic roller  34 . A thickness of the magnetic brush is regulated by the regulating blade  36 . The magnetic brush of which the thickness has been regulated is conveyed to the opposing area R of the magnetic roller  34  and the developing roller  35 . At the opposing area R, the magnetic brush forms a toner layer on the developing roller  35  by voltage difference between a DC voltage applied to the magnetic roller  34  and a DC voltage applied to the developing roller  35  and magnetic field generated by the magnetic roller  34 . 
     The toner layer formed on the developing roller  35  is conveyed by the rotation of the developing roller  35  to an opposing area (a developing area) where the photosensitive drum  1   a  and the developing roller  35  are opposite to each other. Because the predetermined voltage is applied to the developing roller  35 , the toner fries from the developing roller  35  to the photosensitive drum  1   a  owing to voltage difference between the developing roller  35  and the photosensitive drum  1   a,  and develops the latent image on the photosensitive drum  1   a.    
     The development container  30  has a suction opening  37  on a downstream side of the opposing area of the photosensitive drum  1   a  and the developing roller  35  in the rotation direction of the developing roller  35 . Into the suction opening  37 , air containing a floating toner existing near the developing roller  35  is sucked. To the suction opening  37 , a floating toner duct  38  is connected. The floating toner duct  38  extends to the front side of the image forming apparatus  100 . 
     On a front end of the agitating/conveying chamber  31 , a developer discharge opening (not shown) is formed. Through the developer discharge opening, an excessive developer produced in the agitating/conveying chamber  31  and the supplying/conveying chamber  32  as the result of supplying the developer is discharged. 
     The image forming apparatus  100  further includes a waste toner collecting device  40  which collects the toner removed by the drum cleaning devices  7   a  to  7   b,  the toner removed by the belt cleaning device  19 , the floating toner existing near the developing rollers  35  of the developing devices  3   a  to  3   d  and the excessive developer in the developing devices  3   a  to  3   d.    
     With reference to  FIGS. 4 to 7 , the waste toner collecting device  40  will be described.  FIG. 4  is a front side perspective view showing the waste toner collecting device  40 .  FIG. 5  is a front side perspective view showing a floating toner collection chamber  55 .  FIG. 6  is a front side perspective view showing an inside of the floating toner collection chamber  55 .  FIG. 7  is a rear side perspective view showing the waste toner collecting device  40 . 
     The waste toner collecting device  40  includes an intermediate collection box  50 , a waste toner collection container  70  and floating toner collection chambers  55 . The intermediate collection box  50  is disposed on the front side of the image forming parts Pa to Pd. In the intermediate collection box  50 , the removed toner is temporarily stored. The waste toner collection container  70  is disposed below the intermediate collection box  50 . In the waste toner collection container  70 , the removed toner is finally collected. The floating toner collection chambers  55  are provided inside of the intermediate collection box so as to correspond to the image forming parts Pa to Pd. In the floating toner collection chambers  55 , the floating toner is temporarily stored. 
     As shown in  FIG. 4 , the intermediate collection box  50  has a width and a height respectively corresponding to a width and a height of the four image forming parts Pa to Pd, and a predetermined thickness. The intermediate collection box  50  has a base part  50   a  and a lid part  50   b  which forms a horizontally long parallelepiped hollow space S 1 . The base part  50   a  is formed with removed toner receiving openings  51  and floating toner receiving openings  53  (refer to  FIG. 6  also). The removed toner receiving openings  51  are connected to the discharge openings of the drum cleaning devices  7   a  to  7   d.  The floating toner receiving openings  53  are connected to the floating toner ducts  38  of the developing devices  3   a  to  3   d.  The base part  50   a  is further formed with waste developer receiving openings  52  and a removed toner receiving opening  54 . The waste developer receiving openings  52  are connected to the developer discharge openings of the developing devices  3   a  to  3   d.  The removed toner receiving opening  54  is connected to the discharge opening of the belt cleaning device  19 . 
     On a bottom face of the intermediate collection box  50 , a conveying path  50   c  is formed along the left and right directions. The toner and the developer received through the removed toner receiving openings  51  and  54  and the waste developer receiving openings  52  are fallen on the conveying path  50   c  by their own weight. 
     On the conveying path  50   c,  a conveying screw  60  is rotatably supported. The conveying screw  60  is a conveying member which conveys the stored toner. The conveying screw  60  has a rotating shaft  60   a  and a spiral blade  60   b.  The spiral blade  60   b  is spirally formed around the rotating shaft  60   a  in an axis direction of the rotating shaft  60   a  at constant pitches. To one end portion of the rotating shaft  60   a,  a gear  61  is fixedly attached. The gear  61  transmits rotation force from a driving source (not shown) to the rotating shaft  60   a.  As the driving source, a motor which rotates the feed roller  12   a  may be used, for example. The motor has a clutch which allows the rotating shaft  60   a  to be rotated in a normal direction and a reverse direction. 
     At a right end portion of a bottom face of the conveying path  50   c,  a connection pipe  62  connected to the waste toner collection container  70  is connected. On rotating in the normal direction, the conveying screw  60  conveys the toner and developer fallen on the conveying path  50   c  rightward in  FIG. 4 . The toner and developer is conveyed along the conveying path  50   c  and then collected into the waste toner collection container  70  through the connection pipe  62 . The waste toner collection container  70  can be detachably attached to the connection pipe  62 . The waste toner collection container  70  has a sensor which detects an amount of the collected toner and developer. When the sensor detects that a predetermined amount of toner and developer is collected, the waste toner collection container  70  is detached from the connection pipe  62  and the collected toner and developer is discarded. 
     As shown in  FIGS. 5 and 6 , the floating toner collection chamber  55  has a partition wall  55   a  and a lid part  65 . The partition wall  55   a  is stood on the base part  50   a  so as to surround an area containing the floating toner receiving opening  53 . The lid part  65  covers a space surrounded by the partition wall  55   a.  The partition wall  55   a,  the lid part  65  and the base part  50   a  form a horizontally long parallelepiped hollow space S 2 . The hollow space S 2  is isolated from the hollow space S 1  of the intermediate collection box  50 . The floating toner receiving opening  53  is positioned at a right end portion of the floating toner collection chamber  55 . 
     As shown in  FIG. 6 , at a left end portion of the floating toner collection chamber  55 , an exhaust opening  56  is formed on the base part  50   a.  Through the exhaust opening  56 , the hollow space S 2  is evacuated. On the exhaust opening  56 , an air filter  57  is attached with an obliquely downward posture. The air filter  57  blocks passing of the toner but allows passing of air. 
     As shown in  FIG. 7 , on a rear face of the base part  50   a,  an exhaust duct  63  is connected to each exhaust opening  56 . The exhaust ducts  63  are joined to a center of the base part  50   a  in the left and right directions. On a joint portion  63   a  to which the exhaust ducts  63  are joined, an exhaust fan  64  is disposed. In this way, the floating toner duct  38  of each of the developing devices  3   a  to  3   d,  the floating toner collection chamber  55  and the exhaust duct  63  form an exhaust path  59  through which the air containing the floating toner existing near the developing roller  35  of each of the developing devices  3   a  to  3   d  is passed. That is, the floating toner collection chamber  55  forms a middle portion extending from the floating toner receiving opening  53  to the exhaust opening  56  between the floating toner duct  38  and the exhaust duct  63  in the exhaust path  59 . 
     When the exhaust fan  64  is driven, pressure inside of each exhaust duct  63  becomes negative, and pressure inside of each floating toner collection chamber  55  and each floating toner dust  38  become also negative. As a result, the air containing the floating toner existing near each developing roller  35  of the developing devices  3   a  to  3   d  is sucked through the floating toner duct  38  into the floating toner collection chamber  55 . In the floating toner collection chamber  55 , the floating toner contained in the sucked air is collected by the air filter  57  and then stored in the floating toner collection chamber  55 . On the other hand, the air is passed through the exhaust duct  63  and then discharged outside by the exhaust fan  64 . 
     As shown in  FIGS. 5 and 6 , the partition wall  55   a  of the floating toner collection chamber  55  is formed with a protruded portion  55   b  such that the hollow space S 2  of the floating toner collection chamber  55  extends downward from below the air filter  57 . At a lower corner of the protruded portion  55   b,  a discharge opening  55   c  opened in an oblique lower direction is formed. The discharge opening  55   c  is opened and closed by a discharge door  65   a,  as shown in  FIG. 5 . 
     With reference to  FIGS. 8 to 10 , the discharge door  65   a  will be described.  FIG. 8  is a sectional perspective view showing the discharge opening  55   c  closed by the discharge door  65   a.    FIG. 9  is a sectional perspective view showing the discharge opening  55   c  opened by the discharge door  65   a.    FIG. 10  is a front view showing a protruding piece  67  and the spiral blade  60   b.    
     The discharge door  65   a  is connected to the lid part  65 , and turned between a storage position (refer to  FIG. 8 ) and a discharge position (refer to  FIG. 9 ) around an axis approximately parallel to the rotating shaft  60   a  of the conveying screw  60 . In the storage position, the discharge door  65   a  closes the discharge opening  55   c.  In the discharge position, the discharge door  65   a  is turned toward the hollow space S 1  of the intermediate collection box  50  and opens the discharge opening  55   c.  As shown in  FIG. 8 , in the storage position, the discharge door  65   a  extends in an oblique lower direction from the lid part  65 . As shown in  FIG. 9 , in the discharge position, the discharge door  65   a  extends from the lid part  65  downward toward the conveying screw  60  supported by the conveying path  50   c.  The discharge door  65   a  is biased by a biasing member  66  to the storage position. The biasing member  66  is made of elastic material, such as urethane foam, for example. The biasing member  66  is interposed between the lid part  50   b  of the intermediate collection box  50  and the discharge door  65   a.    
     At a tip edge of the discharge door  65   a,  a protruding piece  67  is fixedly attached. As shown in  FIG. 10 , the protruding piece  67  is formed into a trapezoidal shape in a front view, and has a tip edge  67   a  and inclined side edges  67   b  inclined in a direction in which they are approaching each other toward the tip edge  67   a.  The protruding piece  67  is made of elastic material, such as PET film. The protruding pieces  67  has a width W 2  narrower than a pitch W 1  of the spiral blade  60   b  of the conveying screw  60 , and extends in a space between the adjacent spiral blades  60   b  of the conveying screw  60 . 
     With reference to  FIGS. 11A, 11   b,    12 A and  12 B, a tuning operation of the discharge door  65   a  will be described.  FIG. 11A  is a side view showing the discharge door  65   a  turned to the storage position.  FIG. 11B  is a side view showing the discharge door  65   a  turned to the discharge position.  FIG. 12A  is a front view showing the spiral blade  60   b  coming into contact with the inclined edge  67   b  of the protruding piece  67 .  FIG. 12B  is a front view showing the spiral blade  60   b  coming into contact with the tip edge  67   a  of the protruding piece  67 . 
     As shown by a two-dotted line in  FIG. 11A , in a state where the protruding piece  67  extends in the space between the adjacent spiral blades  60   b,  when the conveying screw  60  rotates in the normal direction (the counterclockwise direction in  FIG. 11A ) in order to convey the toner and developer fallen on the conveying path  50   c,  the spiral blade  60   b  comes in contact with the protruding piece  67 . Then, as shown by a solid line in  FIG. 11A , an outer circumferential face of the spiral blade  60   b  presses the protruding piece  67  in a rotation direction of the spiral blade  60   b  as the rotating shaft  60   a  rotates. By being pressed by the spiral blade  60   b,  the protruding piece  67  is deformed and bent with respect to the discharge door  65   a.    
     When the spiral blade  60   b  comes into contact with the protruding piece  67 , as shown in  FIG. 12A , a corner between the outer circumferential face and a front side face of the spiral blade  60   b  in a conveying direction (X in  FIGS. 12A and 12B ) comes into contact with the inclined side edge  67   b  on a rear side in the conveying direction. Then, as shown in  FIG. 12B , the outer circumferential face of the spiral blade  60   b  comes into contact with the tip edge  67   a  of the protruding piece  67  and presses the protruding piece  67  in the normal direction. Because the discharge door  65   a  is biased by the biasing member  66  to the storage position, the discharge door  65   a  is not largely turned by the conveying screw  60 . 
     On the other hand, when the conveying screw  60  is rotated in the reverse direction, as shown in  FIG. 11B , the protruding piece  67  is pressed in the reverse direction by the outer circumferential face of the spiral blade  60   b,  and the discharge door  65   a  is turned to the discharge position against biasing force of the biasing member  66 . The turning operation of the discharge door  65   a  is a reverse operation to the turning operation in the case where the conveying screw  60  is rotated in the normal direction, and its detail description is omitted. When the discharge door  65   a  is turned to the discharge position, the floating toner stored in the floating toner collection chamber  55  is fallen on the conveying path  50   c  through the discharge opening  55   c.  When the rotation of the conveying screw  60  in the reverse direction is stopped, the discharge door  65   a  is biased by the biasing member  66  to the storage position so that the discharge opening  55   c  is closed. 
     A toner collecting operation of the waste toner collecting device  40  having the above described configuration will be described. During the image forming operation, as described above, the toner remained on the photosensitive drums  7   a  to  7   d  in the image forming parts Pa to Pd is removed by the drum cleaning devices  7   a  to  7   d,  respectively. The removed toner is temporarily stored in the intermediate collection box  50  through the removed toner receiving openings  51 . In addition, the toner remained on the intermediate transferring belt  8  after the secondary transferring is removed by the belt cleaning device  19  and then temporarily stored in the intermediate collection box  50  through the removed toner receiving opening  54 . Furthermore, the waste developer is temporarily stored in the intermediate collection box  50  through the waste developer receiving openings  52 . The toner and waste developer received from the receiving openings is fallen on the conveying path  50   c  by their own weight. 
     In the conveying path  50   c,  the conveying screw  60  is driven by the driving source to be rotated in the normal direction and conveys the fallen toner and developer in the conveying direction (rightward). After being conveyed to a right end of the conveying path  50   c,  the toner and developer is then collected into the waste toner collection container  70  through the connection pipe  62 . 
     On the other hand, when the exhaust fan  64  is driven at a suitable timing, the air containing the floating toner near the developing rollers  35  of the developing devices  3   a  to  3   d  is sucked into the exhaust path  59  including the floating toner ducts  38 , the floating toner collection chambers  55  and the exhaust ducts  63 . In the floating toner collection chamber  55  which is a part of the exhaust path  59 , the toner is collected by the air filter  57 . The collected toner is fallen by its own weight and accumulates on upper faces of the partition wall  55   a  and the discharge door  65   a.  On the other hand, the air passing through the air filter  57  is discharged outside through the exhaust duct  63  by the exhaust fan  64 . 
     When an amount of the accumulated toner becomes a predetermined amount, the conveying screw  60  is made to be rotated in the reverse direction for a predetermined period. For instance, the conveying screw  60  is made to be rotated in the reverse direction for 2 to 3 seconds for every 1000 sheets. Then, the spiral blade  60   b  of the conveying screw  60  turns the discharge door  65   a  to the discharge position against the biasing force of the biasing member  66 , as described above. Thereby, the discharge opening  55   c  is opened so that the floating toner accumulated on the upper faces of the discharge door  65   a  and the others is fallen on the conveying path  50   c.  The fallen toner is conveyed along the conveying path  50   c  by the conveying screw  60  together with the collected toner and developer, and collected into the waste toner collection container  70 . 
     In the present embodiment, as described above, the floating toner collection chamber  55  in which the floating toner is temporarily stored is provided in the intermediate collection box  50  in which the toner removed by the drum cleaning devices  7   a  to  7   d  and the belt cleaning device  19  is temporarily stored. And, the floating toner stored in the floating toner collection chamber  55  can be discharged into the intermediate collection box  50 . That is, it is not necessary to provide a floating toner collection container separately from the waste toner collection container  70 . Accordingly, a number of replacement work of the collection containers can be reduces compared with a case where the floating toner collection container and the waste toner collection container  70  are separately provided so that the maintenance performance can be improved. 
     In addition, because it is not necessary to provide a floating toner collection container, enlargement in size of the image forming apparatus  100  can be inhibited. Furthermore, when a detecting sensor which detects the toner collection container being full is provided, only one of the detecting sensor is required so that a configuration of the waste toner collecting device can become simple and cost of it can be reduced. 
     In addition, the discharge door  65   a  is interfered with the spiral blade  60   c  as the conveying screw  60  is rotated, and turned to open and close the discharge opening  55   c  so that a dedicated tuning mechanism of the discharge door  65   a  for opening and closing the discharge opening  55   c  is not required. Accordingly, a configuration of the waste toner collecting device  40  can become simple. 
     In the embodiment, the protruding piece  67  of the discharge door  65   a  is pressed in the direction of the rotation direction of the spiral blade  60   b.  However, the protruding piece  67  may be pressed by the spiral blade  60   b  in the conveying direction and in an opposing direction to the conveying direction. In this case, the discharge door  65   a  may be supported so as to be rotatable around an axis perpendicular to the rotating shaft  60   a  of the conveying screw  60 . And, the protruding piece  67  is made to be extended into a space between the spiral blades  60   b.  Thereby, when the rotating shaft  60   a  is rotated, a front side face or a rear side face of the spiral blade  60   b  in the conveying direction presses the protruding piece  67  in a front side direction or a rear side direction in the conveying direction to turn the discharge door  65   a  and to open or close the discharge opening  55   c.    
     In addition, because the discharge door  65   a  of the floating toner collection chamber  55  is biased to the storage position by the biasing member  66 , the discharge opening  55   c  is closed in a state where the conveying screw  60  is not rotated. Accordingly, when the exhaust fan  64  is driven to make the inside of the exhaust path  59  negative pressure, decrease in the suction force of the exhaust path  59  can be prevented. 
     In addition, use of the air filter  57  can separate the floating toner from the sucked air. Furthermore, because the discharge opening  55   c  is positioned below the air filter  57 , the tonner collected by the air filter  57  can be fallen through the discharge opening  55   c  effectively. 
     The embodiment disclosed in this disclosure is considered to be illustrative in all points but to be restricted. The scope of the disclosure is shown by the scope of the claims not by the detailed description described above, and contains modification of or within an equivalent meanings of the scope of the claims. For instance, although the above embodiment was described in a case where configurations of the disclosure are applied to the color printer, the disclosure it not limited to the embodiment. The configurations of the disclosure may be applied to various image forming apparatus including a waste toner conveying path through which the waste toner is conveyed and an exhaust path through which the floating toner in the developing device is passed, such as a monochromatic printer, a monochromatic copying machine, a color copying machine, a multifunctional peripheral and a facsimile.