Abstract:
A developing device that develops an electrostatic latent image formed on an image holding member with a developer, the device including a developer transporting chamber, a developer transporting member that transports a developer in the developer transporting chamber in a transport direction with stirring, an initial developer collection chamber that, before using of the developer, collects the developer to cause a developer damming member to prevent the developer from dropping into the developer transporting chamber, and removes the developer damming member and forms an integrated space with the developer transporting chamber when the developer is used, to allow the developer to drop into the developer transporting chamber, and a ceiling member that partially narrows a passage for the developer transported by the developer transporting member, up to a height at which interference with the developer is performed, in the transport direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 20I5-147338 filed Jul. 27, 2015. 
     BACKGROUND 
     Technical Field 
     The invention relates to a developing device and an image forming apparatus. 
     SUMMARY 
     According to an aspect of the invention, there is provided a developing device that develops an electrostatic latent image formed on an image holding member with a developer, the device including: 
     a developer transporting chamber; 
     a developer transporting member that is disposed in the developer transporting chamber in a direction extended toward a transport direction, and transports a developer in the developer transporting chamber in the transport direction with stirring; 
     an initial developer collection chamber that is provided at an upper portion of the developer transporting chamber, before using of the developer, collects the developer to cause a developer damming member to prevent the developer from dropping into the developer transporting chamber, and removes the developer damming member and forms an integrated space with the developer transporting chamber when the developer is used, to allow the developer to drop into the developer transporting chamber; and 
     a ceiling member that is disposed in a state of being fixed in the initial developer collection chamber, and partially narrows a passage for the developer transported by the developer transporting member, up to a height at which interference with the developer is performed, in the transport direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is an exterior perspective view of an image forming apparatus as an exemplary embodiment of the invention; 
         FIG. 2  is a schematic diagram illustrating an internal configuration of the image forming apparatus having an appearance illustrated in  FIG. 1 ; 
         FIG. 3  is a schematic diagram illustrating a cross-sectional structure of one developing device; 
         FIGS. 4A to 4C  are schematic cross-sectional views illustrating vertical sections of an initial developer collection chamber and a first developer transporting chamber in a direction perpendicular to a surface of paper of  FIG. 3 , in a developing device as a comparative example; 
         FIGS. 5A to 5C  are schematic cross-sectional views illustrating vertical sections of portions of an initial developer collection chamber and a first developer transporting chamber in a developing device according to this exemplary embodiment; 
         FIG. 6  is a schematic diagram illustrating a ceiling member included in the developing device according to this exemplary embodiment; and 
         FIG. 7  is a schematic diagram illustrating a modification example of the ceiling member. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an exemplary embodiment of the invention will be described. 
       FIG. 1  is an exterior perspective view of an image forming apparatus as an exemplary embodiment of the invention. 
     The image forming apparatus  1  includes an apparatus housing  90  and includes a scanner  10  placed on the apparatus housing  90 , and a printer  20  constituted in the apparatus housing  90 . 
     The scanner  10  is a device that reads an image depicted in an original document and generates an image signal. The printer  20  is a device that prints and outputs an image based on the image signal, on paper by using a so-called electrophotographic process. 
     The scanner  10  includes an original document tray  11  and an original document ejection tray  12 . If original documents are placed on the original document tray  11  in a state of being stacked, and a start button  32  is pushed, each piece of the original document is sequentially fed and read, and then is output onto the original document ejection tray  12 . In the scanner  10 , a hinge (not illustrated) which is extended from side to side is provided and a portion which is higher than a portion indicated by an arrow M may be lift up and be opened. A clear glass plate  13  (see  FIG. 2 ) is spread right under the portion indicated by the arrow M. One piece of an original document is placed downwardly on the clear glass plate  13 , and the portion which is higher than the portion indicated by the arrow M is closed. Then, pressing of the start button  32  may cause the original document on the clear glass plate  13  to be read. 
     The printer  20  is a device that retrieves sequentially each piece of paper from pieces of paper stacked in a paper tray  21  and prints an image based on an image signal onto the retrieved paper. The paper on which an image is printed is output onto an output tray  22 . 
     The image forming apparatus  1  includes a user interface (UI)  30 . The UI  30  includes a power button  31 , the start button  32 , other plural push buttons  33 , and a touch-panel type display screen  34 . Various instructions such as an instruction of the number of printed pieces of paper, and an instruction of starting an operation are performed by operating the UI  30 . A state of this apparatus or various push buttons is displayed on the display screen  34 . A push button displayed on the display screen  34  is also to be operated. 
       FIG. 2  is a schematic diagram illustrating an internal configuration of the image forming apparatus  1  having an appearance illustrated in  FIG. 1 . 
     If the start button  32  (see  FIG. 1 ) is pushed, each piece of an original document S placed on the original document tray  11  of the scanner  10  is fed and transported onto a transporting path  101  by transport rollers  14 . The transported piece of the original document S passes through a reading position R which comes into contact with the clear glass plate  13 , in the middle of the transportation, and then is output onto the original document ejection tray  12 . When the original document S passes through the reading position R, a reading device  15  which is stationary so as to face the reading position R reads and converts an image recorded in the original document S into an image signal. 
     The portion which is higher than the portion indicated by the arrow M is opened, and one piece of an original document S is placed downwardly on the clear glass plate  13 . Then, the start button  32  is pushed. Then, the reading device  15  reads and converts the original document S on the clear glass plate  13  into an image signal with moving of the reading device  15  in a direction indicated by an arrow X. 
     The printer  20  includes four image forming units  50 Y,  50 M,  50 C, and  50 K which are arranged substantially-transversely in a line. The image forming units  50 Y,  50 M,  50 C, and  50 K respectively form toner images by using toners of yellow (Y), magenta (M), cyan (C), and black (K). 
     Each of the image forming units  50 Y,  50 M,  50 C, and  50 K includes a photoreceptor  51 . The photoreceptor  51  receives driving power and thus is rotated in a direction indicated by arrow A. The photoreceptor  51  forms an electrostatic latent image on a surface of the photoreceptor  51  and forms a toner image by developing, while being rotated. 
     A charging device  52 Y,  52 M,  52 C and  52 K, an exposure device  53 Y,  53 M,  53 C and  53 K, a developing device  80 Y,  80 M,  80 C and  80 K, a primary transfer device  62 Y,  62 M,  62 C and  62 K, and a photoreceptor cleaner  55 Y,  55 M,  55 C and  55 K are provided around the photoreceptor  51 Y,  51 M,  51 C and  51 K included in each of the image forming units  50 Y,  50 M,  50 C, and  50 K. Regarding common descriptions in the charging device  52 Y,  52 M,  52 C and  52 K, the exposure device  53 Y,  53 M,  53 C and  53 K, the developing device  80 Y,  80 M,  80 C and  80 K, the primary transfer device  62 Y,  62 M,  62 C and  62 K, the photoreceptor cleaner  55 Y,  55 M,  55 C and  55 K and the photoreceptor  51 Y,  51 M,  51 C and  51 K, reference signs of Y, M, C, and K denoted for distinguishing of colors of the toners are omitted and the charging device  52 Y,  52 M,  52 C and  52 K, the exposure device  53 Y,  53 M,  53 C and  53 K, the developing device  80 Y,  80 M,  80 C and  80 K, the primary transfer device  62 Y,  62 M,  62 C and  62 K, the photoreceptor cleaner  55 Y,  55 M,  55 C and  55 K and the photoreceptor  51 Y,  51 M,  51 C and  51 K are designated the charging device  52 , the exposure device  53 , the developing device  80 , the primary transfer device  62 , the photoreceptor cleaner  55  and the photoreceptor  51 . 
     The primary transfer device  62  is disposed at a position at which an intermediate transfer belt  61  (which will be described later) is interposed between the primary transfer device  62  and the photoreceptor  51 . The primary transfer device  62  is a component included in an intermediate transfer unit  60  (which will be described later), not in the image forming units  50 Y,  50 M,  50 C, and  50 K. 
     The charging device  52  uniformly charges the surface of the photoreceptor  51 . 
     The exposure device  53  irradiates the photoreceptor  51  which is uniformed charged, with exposure light which is modulated based on the image signal. Thus, the exposure device  53  forms an electrostatic latent image on the photoreceptor  51 . 
     The developing device  80  develops the electrostatic latent image formed on the photoreceptor  51  by using the toner of a color corresponding to each of the image forming units  50 Y,  50 M,  50 C, and  50 K. Thus, the developing device  80  forms a toner image on the photoreceptor  51 . 
     The primary transfer device  62  transfers the toner image formed on the photoreceptor  51  onto the intermediate transfer belt  61  (which will be described later). 
     The photoreceptor cleaner  55  has a blade shape. The photoreceptor cleaner  55  is pressed onto the photoreceptor  51 , and scraps the remaining toner and the like which adhere to the photoreceptor  51  after transfer, from the photoreceptor  51 . 
     In the image forming apparatus  1  according to this exemplary embodiment, the developing device  80  has a structure of being detachable by extraction from the apparatus housing  90  and being freely mounted by insertion. In the image forming apparatus  1  according to this exemplary embodiment, the photoreceptor  51  has a structure of being attachable and detachable to and from the apparatus housing  90  in a state of being integrated with the charging device  52  and the photoreceptor cleaner  55  around the photoreceptor  51 . In this exemplary embodiment, the photoreceptor  51  and the like, and the developing device  80  have an individual structure of being attachable and detachable to and from the apparatus housing  90 . However, the photoreceptor  51  and the developing device  80  may have a configuration of being attachable and detachable only in a state of being integrated with each other. 
     The intermediate transfer unit  60  is disposed over the four image forming units  50 Y,  50 M,  50 C, and  50 K. The intermediate transfer unit  60  includes the intermediate transfer belt  61 . The intermediate transfer belt  61  is supported by plural rolls  63   a ,  63   b , and  63   c . The intermediate transfer belt  61  performs circulation movement on a circulation path in a direction indicated by an arrow B. The circulation path includes a path along four photoreceptors  51  which are respectively included in the four image forming units  50 Y,  50 M,  50 C, and  50 K. 
     The toner image on each of the photoreceptors  51  is transferred so as to be sequentially overlapped with each other on the intermediate transfer belt  61 , by an action of the primary transfer device  62 . The toner image transferred onto the intermediate transfer belt  61  is transported to a secondary transfer position T 2  by the intermediate transfer belt  61 . 
     The secondary transfer position T 2  includes a secondary transfer device  71 . The secondary transfer device  71  functions as follows. The secondary transfer device  71  comes into contact with a second surface (which is a back surface of a first surface directed toward the intermediate transfer belt  61  side) of a paper transported to the secondary transfer position T 2 . The secondary transfer device  71  receives application of a transfer voltage and draws the toner image on the intermediate transfer belt  61  to the paper P side so as to cause the toner image to be transferred onto the paper P. 
     After the toner image is transferred onto the paper P, the remaining toner and the like on the intermediate transfer belt  61  is removed from the intermediate transfer belt  61  by an intermediate transfer belt cleaner  64 . 
     The printer  20  has a monochrome mode and a color mode. In the monochrome mode, only the image forming unit  50 K which forms a toner image by using a black (K) toner and is positioned at one end of a sequence (at an end on the leftmost side in  FIG. 2 ) prints a monochrome image on the paper P. In the color mode, a color image is printed on the paper P by using the four image forming units  50 Y,  50 M,  50 C, and  50 K. The intermediate transfer belt  61  moves with coming into contact with the four photoreceptors  51  which respectively constitute the four image forming units  50 Y,  50 M,  50 C, and  50 K, in the color mode by using a cam mechanism (not illustrated). A circulation movement path is changed in the monochrome mode, such that the intermediate transfer belt  61  comes into contact with only a photoreceptor  51 K of the image forming unit  50 K positioned at the one end of the sequence (at the end on the leftmost side in  FIG. 2 ), and is separated from photoreceptors  51 Y,  51 M, and  51 C of other image forming units  50 Y,  50 M, and  50 C. In the monochrome mode, operations of other image forming units  50 Y,  50 M, and  50 C except for the image forming unit  50 K are shopped and thus power saving or component life extending is provided. 
     Toner cartridges  23 Y,  23 M,  23 C and  23 K that respectively collect toners of colors are provided over the intermediate transfer unit  60 . If the toner in the developing device  80  is consumed by developing, the toner is fed from the toner cartridges  23 Y,  23 M,  23 C and  23 K that collect the toner of the corresponding color to the developing device  80  through a toner feeding path (not illustrated). The toner cartridges  23 Y,  23 M,  23 C and  23 K are formed so as to be attachable and detachable. If the toner cartridges  23 Y,  23 M,  23 C and  23 K are empty, the toner cartridges  23 Y,  23 M,  23 C and  23 K are extracted and new toner cartridges  23 Y,  23 M,  23 C and  23 K are mounted. 
     Two paper trays  21  are provided at a lower portion of the printer  20 . Pieces of paper P which are not printed are collected in each of the paper trays  21 , in a state of being stacked. These paper trays  21  are formed to be drawable for replenishment or exchange of paper P. 
     When an image is formed, either of the two paper trays  21  is designated. Every time an image is formed, one piece of paper P is extracted from the designated paper tray  21  by a pickup roll  211 . The extracted piece of paper P is transported to timing adjusting rolls  24  on a transporting path  201  in a direction indicated by an arrow C, by transport rollers  23 . The paper P transported to the timing adjusting rolls  24  is sent toward the secondary transfer position T 2  by the timing adjusting rolls  24  such that the paper P reaches the secondary transfer position T 2  at a timing when the toner image on the intermediate transfer belt  61  reaches the secondary transfer position T 2 . The action of the secondary transfer device  71  causes the toner image to be transferred at the secondary transfer position T 2  onto the paper P sent by the timing adjusting rolls  24  from the intermediate transfer belt  61 . The paper P onto which the toner image has been transferred is transported in a direction indicated by an arrow D, and passes through a fixing machine  72 . The toner image on the paper P is fixed on the paper P by heating and pressing of the fixing machine  72 . Thus, an image formed from the fixed toner image is printed onto the paper P. The paper on which the toner image is fixed by the fixing machine  12  is transported by transport rollers  25  and is sent onto the output tray  22  by output rolls  26 . 
     The printer  20  has a double-sided printing mode in which images are printed on both sides of paper P. In the double-sided printing mode, an image is printed on the first surface of paper P in a manner similar to the above descriptions, and then the paper P of which the image is printed on the first surface is sent to the middle of being transported toward the output tray  22 , by the output rolls  26 . The output rolls  26  reverses the rotation direction thereof and thus draws back the paper P sent to the middle of being transported toward the output tray  22 . 
     The paper P which has been drawn back by reversing of the output rolls  26  is transported on a transporting path  202  in a direction indicated by an arrow G, by transport rollers  27 . Thus, the transported paper P reaches the timing adjusting rolls  24  again. At this time, the paper P has a state where a front surface is reversed when an image is printed on the first surface. After the paper P reaches the timing adjusting rolls  24  again, an image is printed on the second surface of the paper P in a manner similar to the above descriptions. The paper P of which the images have been printed on both of the sides in this manner is sent to the output tray  22  by the output rolls  26 . 
     The printer  20  includes a manual feed tray  28 . If paper is placed on the manual feed tray  28  and then the start button  32  is pushed, the paper on the manual feed tray  28  is transported on a transporting path  203  in a direction indicated by an arrow H, by transport rollers  29 , and reaches the timing adjusting rolls  24 . A printing operation after the paper reaches the timing adjusting rolls  24  is similar to a printing operation performed on the paper P drawn from the paper trays  21 . 
     The image forming apparatus  1  includes a control section  40  for controlling the units. The control section  40  controls the above operations. 
       FIG. 3  is a schematic diagram illustrating a cross-sectional structure of one developing device  80 .  FIG. 3  illustrates a developing device  80  of an initial state before a start of a use. 
     The developing device  80  includes a first developer transporting chamber  81  and a second developer transporting chamber  82  which are extended in a direction perpendicular to the surface of paper so as to be parallel with each other. The first developer transporting chamber  81  and the second developer transporting chamber  82  are linked to each other by passages (first passage  811  and second passage  812  illustrated in  FIGS. 4A to 4C and 5A to 5C ) which are respectively provided at both ends of the developing device  80  in the direction perpendicular to the surface of paper in  FIG. 3 . The first developer transporting chamber  81  and the second developer transporting chamber  82  are empty in an initial state before a start of a use illustrated in  FIG. 3 . A developer has not been collected in the first developer transporting chamber  81  and the second developer transporting chamber  82 . A developer formed from a mixture of a toner and a magnetic carrier is collected in the first developer transporting chamber  81  and the second developer transporting chamber  82 , as will be described later. The first developer transporting chamber  81  includes a first auger  83 . The first auger  83  has a shape extended in the direction perpendicular to the surface of paper, and rotation of the first auger  83  causes the developer in the first developer transporting chamber  81  to be transported in the direction perpendicular to the surface of paper. Similarly, the second developer transporting chamber  82  includes a second auger  84 . Similarly to the first auger  83 , the second auger  84  has a shape extended in the direction perpendicular to the surface of paper, and rotation of the second auger  84  causes the developer in the second developer transporting chamber  82  to be transported in the direction perpendicular to the surface of paper. A direction in which the developer in the first developer transporting chamber  81  is transported by the first auger  83  is reversed to a direction in which the developer in the second developer transporting chamber  82  is transported by the second auger  84 . Accordingly, the developer transported in the first developer transporting chamber  81  by the first auger  83  flows into the second developer transporting chamber  82  at one end portion of the developing device  80  through the first passage  811  (see  FIGS. 4A to 4C and 5A to 5C ) which links the first developer transporting chamber  81  and the second developer transporting chamber  82  to each other. The developer transported in the second developer transporting chamber  82  by the second auger  84  flows into the first developer transporting chamber  81  at another end portion of the developing device  80  through the second passage  812  (see  FIGS. 4A to 4C and 5A to 5C ) which links the first developer transporting chamber  81  and the second developer transporting chamber  82  to each other. In this manner, the developer is circularly transported through the first developer transporting chamber  81  and the second developer transporting chamber  82 . During circular transportation of the developer, the toner and the magnetic carrier constituting the developer are stirred. The stirring causes the toner and the magnetic carrier to be charged with static electricity, and electrostatic force binds the toner and the magnetic carrier to each other. 
     The developing device  80  includes a developing roll  85  at a position of being adjacent to the second developer transporting chamber  82 . Some areas of the developing roll  85  in the rotation direction thereof are in the second developer transporting chamber  82 . Other some areas of the developing roll  85  in the rotation direction thereof are at a position facing the photoreceptor  51 . In the developer in the second developer transporting chamber  82 , the magnetic carrier constituting the developer is pulled to a magnet disposed in the developing roll  85  and is magnetically pressed on the developing roll  85 . The magnetic carrier is transported along with the toner which is electrostatically bound with the magnetic carrier, into an area facing the photoreceptor  51  by rotation of the developing roll  85 . An electrostatic latent image formed on the photoreceptor  51  is developed by using the toner in the developer formed from the toner and the magnetic carrier which has been transported into the area. Thus, a toner image is formed on the photoreceptor  51 . 
     As described above with reference to  FIG. 2 , a toner image formed on the photoreceptor  51  is transferred onto the intermediate transfer belt  61  by the primary transfer device  62 , and is transferred onto paper P by the secondary transfer device  71 . Then, the secondarily-transferred toner image is fixed on the paper P by the fixing machine  72 . In this manner, if the amount of the toner in the developing device  80  is reduced, the insufficient toner is fed from the corresponding toner cartridge  23 Y,  23 M,  23 C and  23 K. 
     In the developing device  80  illustrated in  FIG. 3 , an initial developer collection chamber  86  is provided right over the first developer transporting chamber  81 . A developer  89  is enclosed in the initial developer collection chamber  86  in a state where the developing device  80  has not been used. The initial developer collection chamber  86  and the first developer transporting chamber  81  which is right under the initial developer collection chamber  86  are partitioned off by using an enclosure film  87 . 
     As described above, the developing device  80  is attachable and detachable to and from the apparatus housing  90 . Thus, a design in which the developer  89  or the toner constituting the developer  89  is not leaked from the developing device  80  in a state before a use is required. In the developing device  80  according to this exemplary embodiment, the developer  89  is enclosed in the initial developer collection chamber  86 , and thus leakage is reliably prevented. 
     In the developing device  80 , the enclosure film  87  is pulled out when the developing device  80  is used. If the enclosure film  87  is pulled out, the initial developer collection chamber  86  and the first developer transporting chamber  81  are integrally formed to be one room. The developer which has been enclosed in the initial developer collection chamber  86  is dropped into the first developer transporting chamber  81  and is collected in the first developer transporting chamber  81 . The developing device  80  is mounted to the apparatus housing  90  and an electrostatic latent image on the photoreceptor  51  is developed through the above-described operations by using the toner. A configuration in which the enclosure film  87  is removed after the developing device  80  is mounted to the apparatus housing  90  may be made. 
     Here, descriptions for this exemplary embodiment are suspended, and a comparative example will be described next. For easy understanding,  FIGS. 4A to 4C  illustrate components which correspond to the components in this exemplary embodiment and are denoted by the same reference signs as the reference signs in the drawings illustrating this exemplary embodiment. 
       FIGS. 4A to 4C  are schematic cross-sectional views illustrating vertical sections of an initial developer collection chamber  86  and a first developer transporting chamber  81  in a direction perpendicular to a surface of paper of  FIG. 3 , in a developing device as the comparative example. 
       FIG. 4A  illustrates a not-used state where the developer  89  is enclosed in the initial developer collection chamber  86 .  FIG. 4B  illustrates a state right after the enclosure film  87  is removed.  FIG. 4C  illustrates a state where the developer  89  in the first developer transporting chamber  81  is transported by the first auger  83 . 
     As illustrated in  FIGS. 4A to 4C , the first developer transporting chamber  81  in which the first auger  83  is installed and the initial developer collection chamber  86  right over the first developer transporting chamber  81 , in which the developer  89  is enclosed in the initial state before a use are also provided in the developing device  80  of this comparative example. The first developer transporting chamber  81  includes the first auger  83 . The first auger  83  receives rotation driving force from a driving source (not illustrated) and is rotated in a direction indicated by an arrow L illustrated in  FIG. 4C . If the first auger  83  is rotated, the developer in the first developer transporting chamber  83  is transported in the direction indicated by the arrow X illustrated in  FIG. 4C , with being stirred. As described above, the first passage  811  and the second passage  812  are formed at both end portions of the first developer transporting chamber  81  in a longitudinal direction. Both of the first passage  811  and the second passage  812  are linked to the second developer transporting chamber  82  (see  FIG. 3 ). The first passage  811  is a passage for sending the developer  89  which has been transported in the first developer transporting chamber  81  in the direction indicated by the arrow X, by the first auger  83  to the second developer transporting chamber  82 . The second passage  812  is a passage for inserting the developer  89  which has been transported in the second developer transporting chamber  82  in a direction reverse to the direction indicated by the arrow X, by the second auger  84  illustrated in  FIG. 3 , into the first developer transporting chamber  81  from the second developer transporting chamber  82 . 
     When the developing device  80  is in the initial state of not being used, as illustrated in  FIG. 4A , the developer  89  is enclosed in the initial developer collection chamber  86 , and the initial developer collection chamber  86  and the first developer transporting chamber  81  are completely partitioned off with the enclosure film  87 . 
     When the developing device  80  is to be used, ahead of the use, as illustrated in  FIG. 4B , the enclosure film  87  is removed. If the enclosure film  87  is removed, a ceiling portion of the first developer transporting chamber  81  is opened, and thus the first developer transporting chamber  81  and the initial developer collection chamber  86  forms one room. The developer enclosed in the initial developer collection chamber  86  is dropped and is collected in the first developer transporting chamber  81 . Then, the developing device  80  is accommodated in the apparatus housing  90  of the image forming apparatus  1  illustrated in  FIG. 2  and an operation thereof is started. If the operation is started, the first auger  83  (and the second auger  84  or the developing roll  85 ) is rotated, and the developer in the first developer transporting chamber  81  is transported in the direction indicated by the arrow X. 
     When the operation of the first developer transporting chamber  81  is started as illustrated in  FIG. 4C , the first developer transporting chamber  81  is integrated with the initial developer collection chamber  86  right over the first developer transporting chamber  81 , so as to form one room. The formed room has a high ceiling. However, the initial developer collection chamber  86  has a vertical wall  861  and the vertical wall  861  causes the height of the first passage  811  to be limited to the height of the original first developer transporting chamber  81  excluding the initial developer collection chamber  86 . Thus, even when the developer  89  in the first developer transporting chamber  81  is transported in the direction indicated by the arrow X by rotation of the first auger  83  and reaches the first passage  811 , the entirety of the reached developer  89  may or may not immediately pass through the first passage  811 . That is, particularly, for example, when the toner is fed from the toner cartridge  23 Y,  23 M,  23 C and  23 K (see  FIG. 2 ) and the developer in the developing device  80  is in a bulky state, as illustrated in  FIG. 4C , a state where the developer  89  rises up to a portion of the developing device  80  higher than the first passage  811  occurs. If this state continuously remains for a long time, a portion of the developer  89 , which rises up to the portion of the higher than the first passage  811  is not stirred and stays as it is. Thus, aggregation of the toner proceeds. A certain occasion may cause the developer in the process of the aggregation to pass through the first passage  811  and to be inserted into the second developer transporting chamber  82 , and the developer in the process of the aggregation may be moved to a position facing the photoreceptor  51  by the developing roll  85  and be used for developing an electrostatic latent image. If the developer in the process of the aggregation is used in developing, image defect may occur due to the aggregation. 
     This exemplary embodiment includes a section which is described with reference to  FIGS. 4A to 4C  and is configured to suppress occurrence of the aggregation of the toner in the comparative example. 
       FIGS. 5A to 5C  are schematic cross-sectional views illustrating vertical sections of portions of the initial developer collection chamber  86  and the first developer transporting chamber  81  in the developing device  80  according to this exemplary embodiment. 
     In  FIGS. 5A to 5C , components the same as the components illustrated in  FIGS. 4A to 4C  are denoted by reference signs the same as the reference signs in  FIGS. 4A to 4C . A difference between the components in  FIGS. 4A to 4C and 5A to 5C  will be described. 
       FIG. 6  is a schematic diagram of a ceiling member  91  included in the developing device  80  according to this exemplary embodiment. 
     The developing device  80  in this exemplary embodiment is different from the developing device  80  as the comparative example illustrated in  FIGS. 4A to 4C  in that a ceiling member  91  illustrated in  FIG. 6  is provided. Plural (four in the example described herein) ceiling members  91  are arranged so as to be sequentially disposed at an interval in the transport direction (direction indicated by the arrow X illustrated in  FIG. 5C ) of the developer  89 . The plural ceiling members  91  are supported by one support plate  99 , and are installed in the initial developer collection chamber  86 . 
     An upper end or a side edge of the support plate  99  is fixed to the ceiling or the vertical wall  861  of the initial developer collection chamber  86 , and the support plate  99  has a state of being hung down toward the first developer transporting chamber  81  from the ceiling side. 
     Each of the plural ceiling members  91  supported by the support plate  99  has a peak portion  911  protruding upwardly, and an inclined surface  912  which has a wedge shape and is spread downwardly. Each of the plural ceiling members  91  further has a downward bottom surface  913  at a lower part thereof. The bottom surface  913  is positioned at the undermost end of the initial developer collection chamber  86  and is directed toward the first developer transporting chamber  81  under the bottom surface  913  from the ceiling side. 
     Since the ceiling member  91  has a wedge shape spread downwardly, as illustrated in  FIG. 5B , when the enclosure film  87  is removed, the developer  89  in the initial developer collection chamber  86  is smoothly slipped down on the inclined surface  912  of the ceiling member  91 . Accordingly, the presence of the ceiling member  91  causes occurrence of a situation in which a portion of the developer  89  remains in the initial developer collection chamber  86  and stirring is not performed, and thus the toner is aggregated to be avoided. 
     The developer  89  in the first developer transporting chamber  81  is transported in the direction indicated by the arrow X illustrated in  FIG. 5C , by the first auger  83  during the operation. However, the developer  89  on the ceiling member  91  side at this time has a necessity of passing through a narrow gap which is formed between the bottom surface  913  of the ceiling member  91  and the first auger  83 . Thus, the developer  89  on the ceiling member  91  side is pushed into the narrow gap between the ceiling member  91  and the first auger  83  and is transported in a state of being compressed to a certain extent. In a case of this exemplary embodiment, the first auger  83  has a great-diameter portion  831  at a position facing the ceiling member  91 . Even when the first auger  83  is rotated, the great-diameter portion  831  has a shape which continuously protrudes toward the ceiling member  91 . Thus, a gap at a portion interposed between the ceiling member  91  and the first auger  83  becomes narrower, and the developer  89  which passes through the gap is compressed more. 
     The developer  89  which has passed through the gap interposed between the ceiling member  91  and the first auger  83  is released from the compression. The compression and release from the compression causes aggregation of the toner to be prevented or causes the aggregated toner to be released. Thus, a state of no aggregation occurs. In this exemplary embodiment, since the ceiling members  91  are arranged and the developer  89  is blocked a little by each of the ceiling members  91 , it is possible to avoid occurrence of a bulky state intensively at the part of the first passage  811  and to avoid occurrence of image defect due to the aggregation of the toner. 
     In this exemplary embodiment, the initial developer collection chamber  86  and the first developer transporting chamber  81  respectively correspond to examples of an initial developer collection chamber and a developer transporting chamber. The first auger  83  corresponds to an example of a developer transporting member. The enclosure film  87  corresponds to an example of a developer damming member. The great-diameter portion  831  of the first auger  83  corresponds to an example of a protrusion portion of the developer transporting member. 
       FIG. 7  is a schematic diagram illustrating a modification example of the ceiling member  91 . 
     In  FIG. 7 , components the same as the components illustrated in  FIG. 6  are denoted by reference signs the same as the reference signs in  FIG. 6 . A difference between the components in  FIGS. 6 and 7  will be described. 
     The ceiling member  91  illustrated in  FIG. 7  has a portion at which the inclined surface  912  is formed by being spread downwardly from the peak portion  911  at an upper part so as to be a wedge shape. Subsequently to the portion spread so as to be the wedge shape, the ceiling member  91  has a portion at which a second inclined surface  914  is formed by being narrowed downwardly. The bottom surface  913  is spread between lower end edges of second inclined surfaces  914 . 
     The inclined surface  912  at the portion (which is spread downwardly so to be a wedge shape) of the ceiling member  91  illustrated in  FIG. 7  functions to assist smooth dropping when the developer in the initial developer collection chamber  86  is dropped into the first developer transporting chamber  81 , similarly to the inclined surface  912  of the ceiling member  91  illustrated in  FIG. 6 . 
     Subsequently to the inclined surface  912 , the second inclined surface  914  at the portion narrowed downwardly acts to cause the developer  89  which is transported by the first auger  83  and struck against the ceiling member  91  to be easily inserted into the gap between the bottom surface  913  of the ceiling member  91  and the first auger  83  during an operation. In a case of the ceiling member  91  illustrated in  FIG. 7 , the presence of the second inclined surface  914  causes a probability that the developer  89  struck against the ceiling member  91  holds a state of being struck against the ceiling member  91  to be lowered. Accordingly, concern that image defect occurs due to the aggregation of the toner is reduced. 
     The ceiling member  91  in  FIG. 7  has second inclined surfaces  914  which are formed on both sides of an upstream side and a downstream side in the transport direction of the developer  89 . This is used for completing attachment of the ceiling member  91  without a consideration of a direction of the ceiling member  91  when the ceiling member  91  is attached to the support plate  99 . As the above action, the second inclined surface  914  may be formed only on the upstream side of the transport direction. 
     As the ceiling member  91 ,  FIGS. 6 and 7  illustrate two examples. However, the ceiling member  91  is not limited to the shapes in  FIGS. 6 and 7  and may have any shape as long as the ceiling member  91  forms a narrow gap through which the developer  89  passes between the ceiling member  91  and the first auger  86 . 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.