Patent Publication Number: US-10761455-B2

Title: Replenishment system, developing device, and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2018-176281 filed Sep. 20, 2018. 
     BACKGROUND 
     (i) Technical Field 
     The present disclosure relates to a replenishment system, a developing device, and an image forming apparatus. 
     (ii) Related Art 
     Japanese Unexamined Patent Application Publication No. 2001-249537 describes a developing device including an agitator used to feed toner from a toner hopper to a developer storage case, and an arch-shaped or triangular pyramid-shaped predoctor blade at a toner replenish port. 
     While the amount of a developer accumulated in a path along which toner to be fed to a developer transport path moves is insufficient, a structure that stops toner feeding in response to accumulation of the developer may continue feeding toner sluggishly to the transport path without stopping toner feeding. 
     SUMMARY 
     Aspects of non-limiting embodiments of the present disclosure relate to a structure with an improved performance in stopping feeding of toner from a replenishment path to a transport path compared to a structure that accumulates a developer in only a path. 
     Aspects of certain non-limiting embodiments of the present disclosure address the above advantages and/or other advantages not described above. However, aspects of the non-limiting embodiments are not required to address the advantages described above, and aspects of the non-limiting embodiments of the present disclosure may not address advantages described above. 
     According to an aspect of the present disclosure, there is provided a replenishment system that includes a rotator, a path, and an accumulator. The rotator is disposed above a transport path along which a developer is transported and below a toner replenishment path. The rotator rotates about an axis extending in a transport direction of the transport path while holding the developer. The path is provided downstream of the replenishment path in a rotation direction of the rotator, along a part of an outer circumference of the rotator. The path allows toner from the replenishment path to move therealong in the rotation direction to the transport path. The accumulator is provided in an area including the path and extending from the path outward in a radial direction of the rotator. The accumulator accumulates the developer shifted upward from the transport path. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present disclosure will be described in detail based on the following figures, wherein: 
         FIG. 1  is a schematic diagram of the structure of an image forming apparatus according to an exemplary embodiment; 
         FIG. 2  is a plan view of a developing device according to the exemplary embodiment, from which an upper wall of a housing is omitted; 
         FIG. 3  is a cross-sectional view of the structure of the developing device according to the exemplary embodiment, viewed from the front; 
         FIG. 4  is an enlarged cross-sectional view of a part of the developing device illustrated in  FIG. 3  (cross-sectional view taken along line IV-IV in  FIG. 7 ), viewed from the front; 
         FIG. 5  is an exploded cross-sectional view of a housing, a supporter, and a lid, illustrated in  FIG. 4 , viewed from the front; 
         FIG. 6  is a cross-sectional view of the structure of the developing device according to the exemplary embodiment, viewed from a side; 
         FIG. 7  is a perspective view of the structure of a supporter attached to the housing of the developing device according to the exemplary embodiment; 
         FIG. 8  is a perspective view of the structure of the supporter according to the exemplary embodiment; 
         FIG. 9  is a cross-sectional view of the supporter according to the exemplary embodiment, viewed from a side (cross-sectional view taken along line IX-IX of  FIG. 7 ); and 
         FIG. 10  is a cross-sectional view of a developing device according to a comparative example (first structure), viewed from the front. 
     
    
    
     DETAILED DESCRIPTION 
     Examples of exemplary embodiments according to the disclosure will now be described with reference to the drawings. 
     In the drawings, an arrow UP denotes the upper side of the apparatus (vertically upward), and an arrow DO denotes the lower side of the apparatus (vertically downward). In the drawings, an arrow LH denotes the left side of the apparatus, and an arrow RH denotes the right side of the apparatus. In the drawings, an arrow FR denotes the front of the apparatus, and an arrow RR denotes the rear of the apparatus. These directions are defined for convenience of illustration and do not limit the structure of the apparatus. 
     The upward and downward directions of the apparatus may be referred to as a vertical direction of the apparatus. The leftward and rightward directions of the apparatus may be referred to as a lateral direction of the apparatus. The lateral direction of the apparatus also serves as a width direction (horizontal direction) of the apparatus. The frontward and rearward directions of the apparatus may also be referred to as a front-rear direction of the apparatus. The front-rear direction of the apparatus also serves as a depth direction (horizontal direction) of the apparatus. The directions of the apparatus may be referred to without describing “of the apparatus”. Specifically, for example, “the upper side of the apparatus” may be simply referred to as “the upper side”. 
     In the drawings, the sign of an encircled cross denotes an arrow directing from the near side to the far side of the drawing. In the drawings, the sign of an encircled dot denotes an arrow directing from the far side to the near side of the drawing. 
     Image Forming Apparatus  10   
     An image forming apparatus  10  according to an exemplary embodiment will be described, first.  FIG. 1  is a schematic diagram of a structure of the image forming apparatus  10 . 
     As illustrated in  FIG. 1 , the image forming apparatus  10  includes a sheet containing portion  12 , which contains sheets P, a transporting portion  14 , which transports the sheets P, and an image forming portion  16 , which forms images on the sheets P. 
     Sheet Containing Portion  12   
     The sheet containing portion  12  includes a containing member  12 A, which is drawable frontward from a housing  10 A of the image forming apparatus  10 . The containing member  12 A accommodates a stack of the sheets P. A pick-up roller  14 B is disposed at the sheet containing portion  12 . The pick-up roller  14 B picks up the sheets P stacked in the containing member  12 A and feeds the sheets P to a transport path  14 A constituting the transporting portion  14 . The sheets P are an example of a recording medium. 
     Transporting Portion  14   
     The transporting portion  14  includes, along the transport path  14 A, a pick-up roller  14 B, which picks up the sheets P from the containing member  12 A, and multiple transport rollers  14 C, which transport the sheets P to a sheet discharging portion  10 B via the image forming portion  16 . 
     Image Forming Portion  16   
     The image forming portion  16  includes an image forming unit  18 , which forms black toner images. The image forming unit  18  includes a photoconductor drum  20 , which is an example of a latent image carrier that holds latent images, an exposure device  26 , a charging roller  24 , which serves as a charging device, and a developing device  30 . 
     In the image forming unit  18 , the charging roller  24  charges the photoconductor drum  20  with electricity. The exposure device  26  exposes the photoconductor drum  20  charged by the charging roller  24  with light to form an electrostatic latent image (an example of a latent image). The developing device  30  develops the electrostatic latent image formed on the photoconductor drum  20  by the exposure device  26  into a toner image (an example of an image). The specific structure of the developing device  30  will be described, later. 
     The image forming portion  16  also includes a transfer roller  22 , which is an example of a transfer portion that transfers the toner image developed by the developing device  30  to the sheet P, and a fixing device  28 , which fixes the toner image to the sheet P with heat and pressure. 
     Developing Device  30   
     The developing device  30  will now be described with reference to  FIG. 2  to  FIG. 9 . 
     As illustrated in  FIG. 2  and  FIG. 3 , the developing device  30  includes a transport system  31 , which transports a developer G containing toner TN, a development roller  34 , which is an example of a supplier that supplies the developer G transported by the transport system  31  to the electrostatic latent image on the photoconductor drum  20 , and a replenishment system  39 , which replenishes the transport system  31  with the toner TN. 
     As illustrated in  FIG. 3 , the transport system  31  includes a housing  32 , a lid  33 , a feeding auger  38 , which feeds the developer G to the development roller  34 , a mixing auger  90 , which mixes the developer G, and a projecting portion  80 . The developer G according to the exemplary embodiment is a binary developer containing toner TN and a magnetic carrier as representative components. Here, the toner TN and the developer G are examples of powder. 
     The specific structures of the components of the transport system  31  (the housing  32 , the feeding auger  38 , the mixing auger  90 , and the projecting portion  80 ), the development roller  34 , and the replenishment system  39  are described below. 
     Housing  32   
     As illustrated in  FIG. 3 , the housing  32  accommodates the developer G. The housing  32  is constituted of an open-top box. At the open top of the housing  32 , the lid  33  is disposed. The lid  33  covers the open top of the housing  32 . While a supporter  70 , described later, is disposed in the housing  32 , the lid  33  is disposed at the top of the housing (refer to  FIG. 4  and  FIG. 5 ). 
     As illustrated in  FIG. 3 , the housing  32  is disposed adjacent to (on the left of) the photoconductor drum  20 . At a portion of the housing  32  facing the photoconductor drum  20 , an opening  32 A, which leaves the inside of the housing  32  open, extends in the front-rear direction. On the side of the opening  32 A opposite to the photoconductor drum  20 , a delivery path  32 B on which the development roller  34  is disposed extends in the front-rear direction. 
     Obliquely below the delivery path  32 B, a feed path  32 D on which the feeding auger  38  is disposed extends in the front-rear direction. On the side of the feed path  32 D opposite to the delivery path  32 B, a mixture path  32 C on which the mixing auger  90  is disposed extends in the front-rear direction. 
     The wall surfaces defining the feed path  32 D and the mixture path  32 C have U-shaped cross sections. The mixture path  32 C is a space defined by the wall surface having a U-shaped cross section and an arc-shaped lower surface  85  of the projecting portion  80 , described later. The mixture path  32 C is a cylindrical space, that is, a circular space when viewed in the front-rear direction. Between the feed path  32 D and the mixture path  32 C, a partitioning wall  32 E, which separates the feed path  32 D and the mixture path  32 C from each other, is disposed. 
     As illustrated in  FIG. 2 , in the housing  32 , the feeding auger  38  is disposed to extend from the front to the rear of the feed path  32 D.  FIG. 2  illustrates only the left and right ends of the feeding auger  38 . The mixing auger  90  is disposed to extend from the front to the rear of the mixture path  32 C. 
     The mixture path  32 C and the feed path  32 D have their front ends connected together and their rear ends connected together. The developer G circulates through the mixture path  32 C and the feed path  32 D. The partitioning wall  32 E is disposed between, in the front-rear direction, a connection portion of the front ends of the mixture path  32 C and the feed path  32 D and a connection portion of the rear ends of the mixture path  32 C and the feed path  32 D. 
     Development Roller  34   
     As illustrated in  FIG. 3 , the development roller  34  is disposed on the delivery path  32 B. The development roller  34  faces the photoconductor drum  20  through the opening  32 A of the housing  32 . Between the development roller  34  and the photoconductor drum  20 , a gap (development gap) is formed to deliver the developer G from the development roller  34  to the photoconductor drum  20 . 
     The development roller  34  includes a magnet roller  34 A having a circular cross section, and a rotary sleeve  34 B covering the magnet roller  34 A and rotating around the magnet roller  34 A. 
     The rotary sleeve  34 B receives rotational force from a driving source, not illustrated, and rotates in the direction of arrow A (clockwise) in the drawing. 
     Feeding Auger  38   
     As illustrated in  FIG. 3 , the feeding auger  38  is disposed in the feed path  32 D. Specifically, the feeding auger  38  is disposed in the housing  32 . The feeding auger  38  functions as a transporting member that transports the developer G along the feed path  32 D. Specifically, the feeding auger  38  has a function of transporting the developer G from the rear side to the front side. The feed path  32 D thus has its rear side located upstream in the direction of transporting the developer G and its front side located downstream in the direction of transporting the developer G. Herein, “upstream in the direction of transporting the developer G” may be simply referred to as “upstream”, and “downstream in the direction of transporting the developer G” may be simply referred to as “downstream”. 
     The feeding auger  38  includes a feeding shaft  38 A, extending in the front-rear direction, and a helical feeding blade  38 B, disposed on the outer circumferential surface of the feeding shaft  38 A. 
     Both ends of the feeding shaft  38 A are rotatably supported by wall portions of the housing  32 , so that the feeding shaft  38 A is rotated by a driving source (not illustrated). 
     In this structure, the rotating feeding auger  38  feeds the developer G to the development roller  34  while transporting the developer G on the feed path  32 D from the rear side (upstream side) to the front side (downstream side). The rotating feeding auger  38  delivers the developer G transported to the downstream side (front side) of the feed path  32 D to the mixing auger  90  on the mixture path  32 C on the upstream side (front side) of the mixture path  32 C. Here, the mixture path  32 C is an example of “a transport path”. 
     Mixing Auger  90   
     As illustrated in  FIG. 2  and  FIG. 3 , the mixing auger  90  is disposed on the mixture path  32 C. Specifically, the mixing auger  90  is disposed in the housing  32 . The mixing auger  90  has a function of transporting the developer G along the mixture path  32 C. Specifically, the mixing auger  90  has a function of transporting the developer G from the front side to the rear side. Thus, the mixture path  32 C has its front side disposed upstream in the direction of transporting the developer G, and its rear side disposed downstream in the direction of transporting the developer G. 
     Specifically, the mixing auger  90  includes, as illustrated in  FIG. 6 , a mixing shaft  98 , a first blade  91 , a second blade  92 , a third blade  93 , fourth blades  94 , a pair of protrusions  99 , and a fifth blade  95  (refer to  FIG. 2 ). 
     In the mixing auger  90 , the mixing shaft  98  rotates about the axis extending in the front-rear direction (transport direction) to transport the developer G from the feed path  32 D and the toner fed to the mixture path  32 C from the replenishment system  39  while mixing the developer G and the toner TN with the first blade  91 , the second blade  92 , the third blade  93 , the fourth blades  94 , the pair of protrusions  99 , and the fifth blade  95 . 
     The mixing auger  90  is an example of “a transporting member”. The mixing shaft  98  is an example of “a shaft”. The first blade  91 , the second blade  92 , the third blade  93 , and the fourth blades  94  are examples of “a blade”. 
     Specific structures of the components of the mixing auger  90  (the mixing shaft  98 , the first blade  91 , the second blade  92 , the third blade  93 , the fourth blades  94 , the pair of protrusions  99 , and the fifth blade  95 ) will now be described, below. 
     Mixing Shaft  98   
     As illustrated in  FIG. 2 , the mixing shaft  98  is disposed in the longitudinal direction of the mixture path  32 C. Specifically, the mixing shaft  98  is disposed in the housing  32  to extend in the front-rear direction. The mixing shaft  98  has both ends in the axial direction rotatably supported by the wall portions of the housing  32 . The mixing shaft  98  receives rotational force from the driving source (not illustrated), and rotates in one direction (counterclockwise in  FIG. 3 ) about the axis extending in the front-rear direction (transport direction). 
     As illustrated in  FIG. 2  and  FIG. 6 , the mixing shaft  98  has a large diameter portion  98 A at a portion in the axial direction. The large diameter portion  98 A projects outward in the radial direction of the mixing shaft  98 . Thus, as illustrated in  FIG. 6 , at the upstream and downstream ends of the large diameter portion  98 A in the transport direction, an upstream end surface  98 X, facing upstream (frontward) in the transport direction, and a downstream end surface  98 Y, facing downstream (rearward) in the transport direction, are formed. As illustrated in  FIG. 6 , the large diameter portion  98 A is disposed to the rear of a rotary roller  50 , described later, (disposed downstream in the transport direction) in the front-rear direction (in the transport direction of the mixture path  32 C). 
     As illustrated in  FIG. 6 , the mixing shaft  98  has an immediately upstream portion  98 B, disposed upstream of the large diameter portion  98 A. The immediately upstream portion  98 B is a part of the mixing shaft  98  disposed upstream of the large diameter portion  98 A in the direction of transporting the developer G to be continuous with the large diameter portion  98 A. The immediately upstream portion  98 B is disposed within a limited area of the portion of the mixing shaft  98  upstream of the large diameter portion  98 A in the transport direction. 
     The mixing shaft  98  also has an upstream portion  98 C, disposed upstream of the immediately upstream portion  98 B. The upstream portion  98 C is a part of the mixing shaft  98  disposed upstream of the immediately upstream portion  98 B in the direction of transporting the developer G to be continuous with the immediately upstream portion  98 B. 
     First Blade  91   
     As illustrated in  FIG. 6 , the first blade  91  helically extends on the outer circumferential surface of the large diameter portion  98 A. The first blade  91  transports the developer G to the rear (an example of one side in the axial direction) with rotation of the mixing shaft  98 . Specifically, the first blade  91  is formed from a single blade. 
     The first blade  91  extends to the downstream outer circumferential surface of the large diameter portion  98 A of the mixing shaft  98 . In other words, the first blade  91  transports the developer G rearward beyond the large diameter portion  98 A. The first blade  91  has its radial dimension increased in the downstream side of the large diameter portion  98 A, to compensate for the reduction of the outer diameter of the mixing shaft  98  to be smaller than the large diameter portion  98 A. 
     Second Blade  92   
     As illustrated in  FIG. 6 , the second blade  92  helically extends on the outer circumferential surface of the immediately upstream portion  98 B of the mixing shaft  98 . The second blade  92  transports the developer G to the rear (an example of one side of the axial direction) with the rotation of the mixing shaft  98 . 
     The second blade  92  is continuous with the first blade  91 . In other words, the front end (upstream end) of the first blade  91  is connected to the rear end (downstream end) of the second blade  92 . 
     As illustrated in  FIG. 6 , specifically, the second blade  92  is formed from a single blade. The outer diameter of the second blade  92  is smaller than the outer diameter of the first blade  91 . The helical pitch of the second blade  92  is the same as the helical pitch of the first blade  91 , and smaller than the helical pitch of blades  93 A and  93 B of the third blade  93 , described later, and the helical pitch of blades  94 A and  94 B of the fourth blades  94 , described later. The helical pitch, here, is a length of the blade in the axial direction per 360 degrees (one turn) in the circumferential direction of the mixing shaft  98 . 
     Third Blade  93   
     As illustrated in  FIG. 6 , the third blade  93  helically extends on the outer circumferential surface of the upstream portion  98 C of the mixing shaft  98 . The third blade  93  includes two blades  93 A and  93 B. The two blades  93 A and  93 B of the third blade  93  transport the developer G rearward with rotation of the mixing shaft  98 . 
     Fourth Blade  94   
     As illustrated in  FIG. 6 , the fourth blades  94  are disposed downstream of the first blade  91 , on the outer circumferential surface of the mixing shaft  98 . The fourth blades  94  transport the developer G rearward with rotation of the mixing shaft  98 . 
     Specifically, the fourth blades  94  each include two blades  94 A and  94 B. Multiple (for example, nine) fourth blades  94  are arranged in the axial direction of the mixing shaft  98 . In the fourth blades  94 , the multiple pairs of the two blades  94 A and  94 B transport the developer G rearward with rotation of the mixing shaft  98 . The outer diameter of the blades  94 A and  94 B of the fourth blades  94  is the same as the outer diameter of the first blade  91 , and the outer diameter of the blades  93 A and  93 B of the third blade  93 . 
     Protrusions  99   
     As illustrated in  FIG. 6 , the pair of protrusions  99  are disposed on the outer circumferential surface of the mixing shaft  98  in the area including the fourth blades  94 . The pair of protrusions  99  protrude outward in the radial direction of the mixing shaft  98 . The pair of protrusions  99  protrude outward in the radial direction of the mixing shaft  98  also on the side opposite to the side illustrated in  FIG. 6  and other drawings. The pair of protrusions  99  are disposed at a predetermined distance apart from each other in the axial direction of the mixing shaft  98 . 
     Fifth Blade  95   
     As illustrated in  FIG. 2 , the fifth blade  95  helically extends on the outer circumferential surface at the downstream end (rear end) of the mixing shaft  98  in the transport direction. The fifth blade  95  is a single blade helically wound in the direction opposite to the direction in which the first blade  91 , the second blade  92 , the third blade  93 , and the fourth blades  94  are wound. The fifth blade  95  transports the developer G frontward with rotation of the mixing shaft  98 . The fifth blade  95  prevents the developer G from accumulating at the downstream end (rear end) of the mixture path  32 C, and promotes shift of the developer G from the mixture path  32 C to the feed path  32 D. 
     Replenishment System  39   
     The replenishment system  39  is a system that replenishes the mixture path  32 C with the toner TN. Specifically, as illustrated in  FIG. 3 , the replenishment system  39  includes a toner cartridge  62 , a replenishment path  40 , a rotary roller  50 , and a supporter  70 . 
     Toner Cartridge  62   
     As illustrated in  FIG. 1 , the toner cartridge  62  functions as a container that accommodates the toner TN. The toner cartridge  62  is cylindrical with both ends in the axial direction closed. As illustrated in  FIG. 3 , the toner cartridge  62  has a replenishment port  62 A, through which the toner TN inside falls to replenish the mixture path  32 C with the toner TN. 
     Replenishment Path  40   
     The replenishment path  40  is a path along which the toner is fed to the mixture path  32 C from the toner cartridge  62 . As illustrated in  FIG. 3 , the replenishment path  40  is formed in the lid  33 . Specifically, the replenishment path  40  is open at a portion of the lid  33  obliquely above the mixture path  32 C opposite to (on the left side of) the feed path  32 D, and is connected to the replenishment port  62 A of the toner cartridge  62  disposed above the lid  33 . 
     As illustrated in  FIG. 6 , the replenishment path  40  is open at a portion upstream of (in front of) the large diameter portion  98 A of the mixing shaft  98 . Specifically, the replenishment path  40  is open at a portion upstream of (in front of) the projecting portion  80 , and upstream of (in front of) the large diameter portion  98 A of the mixing shaft  98 . 
     In other words, the exemplary embodiment has a structure in which the housing  32  (specifically, the mixture path  32 C) is replenished with the toner TN at a portion upstream of (in front of) the projecting portion  80 , and upstream of (in front of) the large diameter portion  98 A of the mixing shaft  98 . The replenishment path  40  is an example of “a toner replenishment path”. 
     Rotary Roller  50   
     As illustrated in  FIG. 4 , the rotary roller  50  is disposed below the replenishment path  40 . When viewed in a plan, the opening of the replenishment path  40  at the downstream end is smaller than the outer dimension of the rotary roller  50 . The rotary roller  50  is disposed at a portion that covers the opening. 
     The rotary roller  50  is disposed above the mixture path  32 C. Specifically, the lower end of the rotary roller  50  is disposed below the upper end of the mixing auger  90  when viewed in the axial direction of the rotary roller  50  and the mixing auger  90 . The right end portion of the rotary roller  50  is disposed to the right of the left end portion of the mixing auger  90 . Specifically, the rotary roller  50  and the mixing auger  90  are disposed to vertically and laterally overlap each other. 
     As illustrated in  FIG. 6 , the rotary roller  50  is disposed above the immediately upstream portion  98 B of the mixing shaft  98 , along the mixing shaft  98 . Specifically, the rotary roller  50  is disposed to extend above and across the immediately upstream portion  98 B and the upstream portion  98 C of the mixing shaft  98 . 
     As illustrated in  FIG. 3  and  FIG. 9 , the rotary roller  50  includes a magnet roller  50 A, which is a magnetic body, and a rotary sleeve  50 B. 
     The magnet roller  50 A is cylindrical. As illustrated in  FIG. 9 , the magnet roller  50 A includes a shaft portion  50 C, which protrudes from a first end in the axial direction (rear end) to a first side in the axial direction (to the rear side). The magnet roller  50 A has a function of holding the developer G on the outer circumference of the rotary sleeve  50 B with the magnetic force. 
     As illustrated in  FIG. 4 , the rotary sleeve  50 B is a cylinder that covers the outer circumference of the magnet roller  50 A. Specifically, the rotary sleeve  50 B is a cylinder having a second end in the axial direction (front end) closed. As illustrated in  FIG. 9 , the rotary sleeve  50 B includes a shaft portion  50 D, which protrudes from a second end in the axial direction (front end) to a second side in the axial direction (to the front side). 
     The magnet roller  50 A is fixed to the supporter  70  so as not to rotate. On the other hand, the rotary sleeve  50 B is rotated by a driving source  59  (refer to  FIG. 2 ) about an axis extending in the front-rear direction around the outer circumference of the magnet roller  50 A in the direction of arrow B. Specifically, the rotary sleeve  50 B rotates about the axis extending in the transport direction of the mixture path  32 C. 
     As illustrated in  FIG. 4 , the magnet roller  50 A has, inside, a first magnetic pole Gl, a second magnetic pole G 2 , and a third magnetic pole G 3 . In the exemplary embodiment, for example, the first magnetic pole G 1  is a south pole, the second magnetic pole G 2  is a north pole, and the third magnetic pole G 3  is a south pole. The rotary roller  50  holds the developer G on the outer circumference of the rotary sleeve  50 B using the magnetic field formed by the first magnetic pole Gl, the second magnetic pole G 2 , and the third magnetic pole G 3 . 
     The rotary roller  50  holds the developer G over a holding area  51  (refer to  FIG. 8 ) of the rotary sleeve  50 B at a center portion in the axial direction. As illustrated in  FIG. 8 , in the holding area  51  of the rotary sleeve  50 B, recesses  52  and ridges  53  are formed on the outer circumferential surface. The recesses  52  and the ridges  53  are alternately arranged in the circumferential direction of the rotary roller  50 . The recesses  52  and the ridges  53  extend in the axial direction of the rotary roller  50 . As illustrated in  FIG. 6 , the dimension of the holding area  51  in the front-rear direction is equivalent to the dimension of the replenishment path  40  in the front-rear direction. Specifically, when viewed in the lateral direction, the rear end of the holding area  51  is flush with the rear end of the replenishment path  40 , and the front end of the holding area  51  is flush with the front end of the replenishment path  40 . The rotary roller  50  is an example of “a rotator”. 
     Supporter  70   
     The supporter  70  illustrated in  FIG. 3 ,  FIG. 4 ,  FIG. 5 , and  FIG. 7  has a function of supporting the rotary roller  50 . As illustrated in  FIG. 5 , the supporter  70  is separate from the housing  32  having the mixture path  32 C inside. Specifically, as illustrated in  FIG. 8 , the supporter  70  includes a first support portion  71 , a second support portion  72 , a coupling portion  76 , a forming portion  78 , and a projecting portion  80 . The first support portion  71 , the second support portion  72 , the coupling portion  76 , the forming portion  78 , and the projecting portion  80  are integrated together, and the supporter  70  is formed from a single structure. 
     The first support portion  71  has a supporting function of supporting a first end portion (rear end portion) of the rotary roller  50  in the axial direction. Specifically, as illustrated in  FIG. 9 , the first support portion  71  has a function of supporting the magnet roller  50 A of the rotary roller  50 . The first support portion  71  is disposed at a first end side (rear side) of the rotary roller  50  in the axial direction. The first support portion  71  has a thickness in the front-rear direction, and is formed from a wall portion having a circular hole  71 A. Into a circular hole  71 A of the first support portion  71 , a fastening member  74 , which fastens the shaft portion  50 C of the magnet roller  50 A, is attached. Thus, the magnet roller  50 A is supported by the supporter  70  while being left unrotatable (fixed in position) with respect to the supporter  70 . 
     The second support portion  72  has a supporting function of rotatably supporting the second end portion (front end) of the rotary roller  50  in the axial direction. 
     Specifically, the second support portion  72  has a function of rotatably supporting the rotary sleeve  50 B of the rotary roller  50 . 
     As illustrated in  FIG. 8 , the second support portion  72  is disposed at the second end side (front side) of the rotary roller  50  in the axial direction. The second support portion  72  extends to the front side of the rotary roller  50 , and is cylindrical with its axis extending in the front-rear direction. As illustrated in  FIG. 9 , a bearing  73 , which rotatably supports the shaft portion  50 D of the rotary sleeve  50 B, is disposed inside the second support portion  72 . The shaft portion  50 D of the rotary sleeve  50 B supported by the bearing  73  receives driving force from the driving source  59  (refer to  FIG. 2 ) via a transmission portion  57 , and, as illustrated in  FIG. 4 , the rotary sleeve  50 B rotates around the magnet roller  50 A in the direction of arrow B. 
     As illustrated in  FIG. 8 , the coupling portion  76  has a function of coupling the first support portion  71  and the second support portion  72 , together. Specifically, the coupling portion  76  couples the left end portion of the first support portion  71  and the left end portion of the second support portion  72  together. The coupling portion  76  extends in the front-rear direction. The rear end of the coupling portion  76  is connected to the left end portion of the first support portion  71 , and the front end of the coupling portion  76  is connected to the left end portion of the second support portion  72 . 
     As illustrated in  FIG. 4  and  FIG. 7 , the coupling portion  76  is supported on a left wall  32 Y (side wall) of the housing  32 . Between the coupling portion  76  and the left wall  32 Y and the rotary roller  50 , as illustrated in  FIG. 4 , a first path  44 , which connects the mixture path  32 C and the replenishment path  40 , is disposed. Specifically, the first path  44  is provided upstream of the replenishment path  40  in the rotation direction B of the rotary roller  50 , and along a part of the outer circumference of the rotary roller  50 . The first path  44  allows the developer G and the toner TN to pass therealong. 
     As illustrated in  FIG. 5  and  FIG. 8 , the forming portion  78  is a portion at which the projecting portion  80  is disposed. As illustrated in  FIG. 8 , the forming portion  78  couples the right end portion of the first support portion  71  and the right end portion of the second support portion  72 , together. The forming portion  78  extends in the front-rear direction, and as illustrated in  FIG. 4  and  FIG. 7 , and projects from the first support portion  71  and the second support portion  72  toward the mixing auger  90  (to the right side) of the rotary roller  50 . 
     The forming portion  78 , the first support portion  71 , the second support portion  72 , and the coupling portion  76  form the supporter  70  having a frame shape having a connection port  79 , when viewed in a plan (refer to  FIG. 7 ). As illustrated in  FIG. 4 , the connection port  79  is connected to a lower end portion of the replenishment path  40 . The dimension of the connection port  79  in the front-rear direction is longer than the dimension of the replenishment path  40  in the front-rear direction. 
     The forming portion  78 , which projects to the right of the rotary roller  50 , is disposed above the mixing auger  90  (mixture path  32 C). As illustrated in  FIG. 4  and  FIG. 7 , the right end portion of the forming portion  78  is supported by an upper end portion of the partitioning wall  32 E. 
     Between the forming portion  78  and the rotary roller  50 , as illustrated in  FIG. 4 , a second path  46 , which connects the mixture path  32 C and the replenishment path  40  to each other, is provided. Specifically, the second path  46  is disposed downstream of the replenishment path  40  in the rotation direction B of the rotary roller  50 , along a part of the outer circumference of the rotary roller  50 . The second path  46  allows the developer G and the toner TN to move therealong. The toner from the replenishment path  40  moves along the second path  46  in the rotation direction B to the mixture path  32 C. The second path  46  is an example of “a path”. 
     The forming portion  78  forms a path surface  87  of the second path  46  along a part of the outer circumferential surface of the rotary roller  50  in the circumferential direction. The path surface  87  is a surface facing the outer circumferential surface of the rotary roller  50 , and is shaped in an arc when viewed in the axial direction. Specifically, the path surface  87  has a shape of an arc of a circle having a center at the rotation center of the rotary roller  50 . 
     As illustrated in  FIG. 4  and  FIG. 8 , the projecting portion  80  projects to the mixture path  32 C from the forming portion  78 . Specifically, as illustrated in  FIG. 4 , the projecting portion  80  projects to the mixture path  32 C from the upper side of the mixture path  32 C. 
     Specifically, the projecting portion  80  projects downward from the forming portion  78  toward the large diameter portion  98 A of the mixing shaft  98  of the mixing auger  90 . In other words, the projecting portion  80  projects downward toward the large diameter portion  98 A from above the large diameter portion  98 A in the axial direction of the mixing shaft  98 . 
     The lower surface  85  of the projecting portion  80  is formed in an arc, when viewed in the axial direction of the mixing shaft  98 , extending along the outer circumferential surface of the large diameter portion  98 A. The lower surface  85  forms the path surface of the mixture path  32 C. 
     In other words, the projecting portion  80  has a function of reducing the path width of the large diameter portion  98 A and the mixture path  32 C around the large diameter portion  98 A. More specifically, the projecting portion  80  has a function of reducing the volume (capacity) of the mixture path  32 C around the large diameter portion  98 A and its periphery. 
     As illustrated in  FIG. 6 , at the upstream and downstream ends of the projecting portion  80  in the transport direction, an upstream end surface  82 , facing upstream (frontward) in the transport direction, and a downstream end surface  84 , facing downstream (rearward) in the transport direction, are formed.  FIG. 6  illustrates the projecting portion  80  in a cross section taken along dot-dash line H 1  in  FIG. 4 .  FIG. 6  illustrates the lid  33  and the replenishment path  40  in cross sections taken along dot-dash line M in  FIG. 4 . 
     The upstream end surface  82  of the projecting portion  80  serves as a stopper surface that stops the developer G transported along the mixture path  32 C. The upstream end surface  82  may be also referred to as a stopper surface  82 , below. The stopper surface  82  stops the developer G transported along the mixture path  32 C to accumulate the developer G. 
     As illustrated in  FIG. 4 , an accumulation space  75  in which the developer G is accumulated by the stopper surface  82  is formed in the area including the second path  46  and extending from the second path  46  outward (to the right side) in the radial direction of the rotary roller  50 . In the accumulation space  75 , the developer G stopped by the stopper surface  82  and shifted upward from the mixture path  32 C accumulates. The accumulation space  75  is an example of an accumulator. 
     In other words, the accumulation space  75  includes the second path  46 , and the area in which the toner TN moving along the second path  46  does not pass. Specifically, the accumulation space  75  includes an area in which the toner TN does not pass when moving from the replenishment path  40  to the mixture path  32 C. In other words, the stopper surface  82  may be regarded as including a portion that the toner TN moving along the second path  46  does not touch. Furthermore, the accumulation space  75  may be regarded as including an area other than the flow path from the replenishment path  40  to the mixture path  32 C. 
     More specifically, the accumulation space  75  is a space above the mixture path  32 C. As described above, the mixture path  32 C is a space defined by the wall surface of the housing  32  having a U-shaped cross section, and the arc-shaped lower surface  85  of the projecting portion  80 , and is a circular space when viewed in the front-rear direction. 
     As illustrated in  FIG. 6 , the stopper surface  82  is disposed upstream of the downstream end of the rotary roller  50  in the transport direction. Specifically, the stopper surface  82  is disposed downstream of the upstream end of the rotary roller  50  in the transport direction, and upstream of the downstream end of the rotary roller  50  in the transport direction. More specifically, the stopper surface  82  is disposed between the downstream end of the holding area  51  of the rotary roller  50  in the transport direction, and the downstream end of the rotary roller  50  in the transport direction. More specifically, the stopper surface  82  is flush with the downstream end of the holding area  51  of the rotary roller  50  in the transport direction. In other words, the stopper surface  82  is disposed at the same position, in the front-rear direction, as the downstream end of the holding area  51  of the rotary roller  50  in the transport direction. 
     The stopper surface  82  is flush with the downstream end of the replenishment path  40  in the transport direction. Specifically, the stopper surface  82  is disposed at the same position, in the front-rear direction, as the downstream end of the replenishment path  40  in the transport direction. 
     As illustrated in  FIG. 4  and  FIG. 8 , the forming portion  78  has a restriction surface  89 , disposed above the lower surface  85  of the projecting portion  80  to restrict upward shift of the developer G accumulated in the accumulation space  75 . When viewed in the front-rear direction (when viewed in the axial direction of the rotary roller  50 ), the restriction surface  89  extends rightward (outward in the radial direction of the rotary roller  50 ) from the lower end of the path surface  87 . The restriction surface  89  is a surface facing downward to the mixing auger  90 . The restriction surface  89  is disposed below the upper end of the rotary roller  50 . The restriction surface  89  may be also said as being disposed below the lower end (downstream end) of the replenishment path  40 . Furthermore, the restriction surface  89  may be also said as being disposed below the upper end (upstream end) of the second path  46 . The restriction surface  89  is disposed above the rotation center of the rotary roller  50 . In other words, the restriction surface  89  is disposed at a portion that the toner TN moving along the second path  46  does not touch. 
     The forming portion  78  also includes an inclined surface  88 , which extends obliquely downward to the right from the right end of the restriction surface  89  when viewed in the front-rear direction. The accumulation space  75  may be also said as a space including a space defined by the stopper surface  82 , the restriction surface  89 , and the inclined surface  88 . 
     The accumulation space  75  includes an area on a side of a vertically upper position of the rotation center of the mixing auger  90 , the side being opposite to the side closer to the second path  46  (on the right side of the vertically upper position). Dot-dash line H 1  illustrated in  FIG. 4  is an extension line extended vertically upward from the rotation center Cl of the mixing auger  90 . The accumulation space  75  may be an area extending from the second path  46  to the side of the extension line H 1  closer to the second path  46  (on the left side of the extension line H 1 ). 
     The accumulation space  75  extends upstream from the second path  46  in the rotation direction of the mixing shaft  98 . Specifically, the accumulation space  75  extends around the mixing shaft  98  counterclockwise in  FIG. 4 . In other words, the accumulation space  75  extends rightward from the second path  46 . In other words, in the present exemplary embodiment, the mixing auger  90  may be regarded as rotating from the right end portion (the end farther from the second path  46 ) of the accumulation space  75  toward the second path  46  (to the left side). The supporter  70  itself may be regarded as an example of the replenishment system. 
     Operation of Rotary Roller  50   
     In the rotary roller  50 , as illustrated in  FIG. 4 , the rotary sleeve  50 B regularly rotates in the direction of arrow B. In the rotary roller  50 , the magnetic field formed by the first magnetic pole Gl, the second magnetic pole G 2 , and the third magnetic pole G 3  holds, at the position of the first magnetic pole G 1  on the outer circumference of the rotary sleeve  50 B, the developer G accumulated upstream of the large diameter portion  98 A of the mixing shaft  98  (the immediately upstream portion  98 B and the upstream portion  98 C). Then, with rotation of the rotary sleeve  50 B, the developer G is transported to the third magnetic pole G 3 , and released at the position of the third magnetic pole G 3 . 
     Development Operation of Developing Device 
     The operation of the developing device  30  will now be described. 
     In the housing  32  of the developing device  30  illustrated in  FIG. 2 , the rotating feeding auger  38  and the rotating mixing auger  90  circulate the developer G between the feed path  32 D and the mixture path  32 C while mixing the developer G. 
     When the developer G is mixed, the toner TN and the magnetic carrier in the developer G are rubbed against each other, and the toner TN is charged by friction with a predetermined polarity. 
     The feeding auger  38  illustrated in  FIG. 3  feeds the developer G to the development roller  34 . The developer G fed to the development roller  34  is held on the surface of the development roller  34  in the form of a magnetic brush (not illustrated) with the magnetic force of the magnet roller  34 A. 
     The rotating rotary sleeve  34 B then transports the developer G to a position facing the photoconductor drum  20 . 
     The toner TN contained in the developer G transported to a development gap of the photoconductor drum  20  adheres to an electrostatic latent image formed on the photoconductor drum  20 , and the electrostatic latent image is thus developed into a toner image. 
     Thus, the developing device  30  feeds to the photoconductor drum  20  the developer G to form an image on the sheet P. The developing device  30  is replenished with the toner TN in the following manner. 
     Operation of Replenishment with Toner TN 
     As illustrated in  FIG. 4 , in the developing device  30 , the rotary sleeve  50 B of the rotary roller  50  regularly rotates in the direction of arrow B. The magnetic field formed by the first magnetic pole G 1 , the second magnetic pole G 2 , and the third magnetic pole G 3  holds, at the position of the first magnetic pole G 1  on the outer circumference of the rotary sleeve  50 B, the developer G accumulated upstream of the large diameter portion  98 A of the mixing shaft  98  (the immediately upstream portion  98 B and the upstream portion  98 C). With rotation of the rotary sleeve  50 B, the developer G is transported to the third magnetic pole G 3 , and released at the position of the third magnetic pole G 3 . 
     Specifically, the rotary roller  50  holds the developer G accumulated upstream of the large diameter portion  98 A of the mixing shaft  98 , and allows the holding developer G to pass along the first path  44  and the second path  46 . When the amount of the developer G in the mixture path  32 C decreases through consumption and thus the amount of the developer G accumulated upstream of the large diameter portion  98 A of the mixing shaft  98  decreases, the amount of the developer G held by the rotary roller  50  decreases in the replenishment system  39 , and the second path  46  and the replenishment path  40  are rendered open. Thus, the toner TN is fed to the mixture path  32 C along the second path  46  and the replenishment path  40 . 
     On the other hand, when the amount of the developer G in the mixture path  32 C increases with the replenishment with the toner TN and the amount of the developer G accumulated upstream of the stopper surface  82  increases, the developer G transported by the mixing auger  90  is stopped by the stopper surface  82  of the projecting portion  80  in the replenishment system  39 , and concurrently, the amount of the developer G held by the rotary roller  50  increases. 
     When the developer G transported by the mixing auger  90  is stopped by the stopper surface  82 , the developer G is accumulated in the accumulation space  75  included in the second path  46 . Furthermore, the developer G held by the rotary roller  50  is transported to the second path  46 , and added to the developer G accumulated in the accumulation space  75 , so that the amount of the developer G accumulated in the second path  46  increases. Thus, the second path  46  and the replenishment path  40  are clogged with the developer G. Thus, the replenishment of the toner TN to the mixture path  32 C through the second path  46  and the replenishment path  40  is stopped. Specifically, the present exemplary embodiment serves its shutter function of stopping replenishment of the toner TN in response to the second path  46  and the replenishment path  40  being clogged with the developer G. 
     Operation of Exemplary Embodiment 
     In the present exemplary embodiment, as illustrated in  FIG. 4 , the accumulation space  75  is provided in an area including the second path  46  and extending from the second path  46  outward (rightward) in the radial direction of the rotary roller  50 . In other words, the accumulation space  75  includes the second path  46  and the area in which the toner TN moving along the second path  46  does not pass. 
     Compared to a structure that accumulates the developer G with only the second path  46  without the accumulation space  75  (first structure in  FIG. 10 ), the amount of the developer G that accumulates in the accumulation space  75  (hereinafter referred to as an accumulated developer) increases. Thus, compared to the first structure, the accumulated developer is less likely to collapse, and the developer G transported by the rotary roller  50  to the second path  46  is supported by the accumulated developer. Then, the developer G transported by the rotary roller  50  to the second path  46  is accumulated in the second path  46  on the accumulated developer, serving as a base. Thus, compared to the first structure, this structure is more likely to allow the second path  46  and the replenishment path  40  to be clogged with the developer G, and improves the function (that is, shutter function) of stopping feeding of toner from the replenishment path  40  to the mixture path  32 C. 
     In the exemplary embodiment, the accumulation space  75  allows the developer G shifted upward from the mixture path  32 C to be accumulated therein by stopping the developer G with the stopper surface  82 . 
     Thus, compared to the structure (second structure) that does not include the projecting portion  80  and that accumulates the developer G without stopping the developer G with the stopper surface  82 , the developer G is prevented from moving downstream in the transport direction, and remains accumulated. Thus, compared to the second structure, this structure improves the function of stopping feeding of toner from the replenishment path  40  to the mixture path  32 C. 
     In the present exemplary embodiment, the stopper surface  82  is disposed upstream of the downstream end of the rotary roller  50  in the transport direction. Thus, compared to a structure (third structure) in which the stopper surface  82  is disposed downstream of the downstream end of the rotary roller  50  in the transport direction, the developer G is more likely to accumulate at a portion holdable by the rotary roller  50 . Thus, compared to the third structure, this structure improves the function of stopping feeding of toner from the replenishment path  40  to the mixture path  32 C. 
     In the present exemplary embodiment, the stopper surface  82  is flush with the downstream end of the replenishment path  40  in the transport direction. Thus, compared to the structure (fourth structure) in which the stopper surface  82  is disposed downstream of the downstream end of the replenishment path  40  in the transport direction, the developer G is more likely to accumulate at the position of the replenishment path  40 . Thus, compared to the fourth structure, this structure improves the function of stopping feeding of toner from the replenishment path  40  to the mixture path  32 C. 
     In the present exemplary embodiment, the stopper surface  82  is formed at the upstream end of the projecting portion  80  in the transport direction. Thus, compared to the structure in which the stopper surface  82  is formed at a member different from the projecting portion  80 , this structure reduces the number of components. 
     In the present exemplary embodiment, the projecting portion  80  has the restriction surface  89 , which restricts upward shift of the developer G accumulated in the accumulation space  75 . Compared to the structure (fifth structure) that allows upward shift of the developer G accumulated in the accumulation space  75 , this structure prevents the developer G from moving upward, and keeps the developer G in the accumulated state. Thus, compared to the fifth structure, this structure improves the function of stopping feeding of toner from the replenishment path  40  to the mixture path  32 C. 
     In the present exemplary embodiment, the accumulation space  75  includes the area on the side of a vertically upper position of the rotation center of the mixing auger  90 , the side being opposite to the side closer to the second path  46  (on the right side of the vertically upper position). Thus, compared to the structure (sixth structure) in which the accumulation space  75  is disposed only in the area on the side of the vertically upper position of the rotation center of the mixing auger  90  closer to the second path  46  (on the left side of the vertically upper position), this structure allows the developer G shifted upward from the mixing auger  90  to accumulate over a wider area. Thus, compared to the sixth structure, the accumulated developer G is less likely to collapse, and the second path  46  and the replenishment path  40  are more likely to be clogged. Thus, compared to the sixth structure, this structure improves the function of stopping feeding of toner from the replenishment path  40  to the mixture path  32 C. 
     In the present exemplary embodiment, the accumulation space  75  extends from the second path  46  upstream in the rotation direction of the mixing shaft  98 . Here, the mixing auger  90  transports the developer G with, for example, the second blade  92  and the third blade  93  with rotation of the mixing shaft  98 . Thus, the developer G is more likely to move downstream in the rotation direction by being pushed by, for example, the second blade  92  and the third blade  93 . Thus, the developer G that shifts upward from the mixture path  32 C is more likely to move to the second path  46  in the accumulation space  75  (downstream or leftward in the rotation direction of the mixing shaft  98 ) compared to the structure (seventh structure) in which the accumulation space  75  extends from the second path  46  only downstream in the rotation direction of the mixing shaft  98 . 
     Thus, compared to the seventh structure, this structure accumulates the developer G in the second path  46  of the accumulation space  75 , and improves the function of stopping feeding of toner from the replenishment path  40  to the mixture path  32 C. 
     In the present exemplary embodiment, as illustrated in  FIG. 5 , the supporter  70  that supports the rotary roller  50  and includes the second path  46  and the accumulation space  75  is separate from the housing  32  including the mixture path  32 C therein. Thus, when the supporter  70  is removed from the housing  32 , the rotary roller  50 , the second path  46 , and the accumulation space  75  are integrally removed from the housing  32 . Thus, the rotary roller  50 , the second path  46 , and the accumulation space  75  are allowed to be subjected to adjustment, replacement, and maintenance while being detached from the housing  32 . 
     The present exemplary embodiment thus improves the function of stopping feeding of toner from the replenishment path  40  to the mixture path  32 C, and thus prevents a variation of the toner density in the developer G. Specifically, the exemplary embodiment prevents an increase in the toner density of the developer G transported along the mixture path  32 C. With the increase in the toner density of the developer G being prevented, the developing device  30  reduces development errors, and image quality degradation of the toner image formed on the sheet P is reduced. 
     Modification Example 
     In the present exemplary embodiment, the accumulation space  75  allows the developer G shifted upward from the mixture path  32 C to accumulate therein by stopping the developer G with the stopper surface  82 . This is, however, not the only possible structure. For example, the developer G may be accumulated only with the large diameter portion  98 A. 
     In the present exemplary embodiment, the stopper surface  82  is disposed downstream of the upstream end of the rotary roller  50  in the transport direction, and upstream of the downstream end of the rotary roller  50  in the transport direction. This is, however, not the only possible structure. For example, the stopper surface  82  may be disposed upstream of the upstream end of the rotary roller  50  in the transport direction, or the stopper surface  82  may be disposed downstream of the downstream end of the rotary roller  50  in the transport direction. 
     In the present exemplary embodiment, the stopper surface  82  is flush with the downstream end of the replenishment path  40  in the transport direction. This is, however, not the only possible structure. For example, the stopper surface  82  may be disposed downstream of the downstream end of the replenishment path  40  in the transport direction. 
     In the present exemplary embodiment, the stopper surface  82  is disposed at the upstream end of the projecting portion  80  in the transport direction. This is, however, not the only possible structure. For example, the stopper surface  82  may be disposed at a member different from the projecting portion  80 . 
     In the present exemplary embodiment, the projecting portion  80  has the restriction surface  89  that restricts upward shift of the developer G accumulated in the accumulation space  75 . This is, however, not the only possible structure. For example, the developer G may be only stopped by the stopper surface  82 . 
     In the present exemplary embodiment, the accumulation space  75  includes an area on the side of the vertically upper portion of the rotation center of the mixing auger  90 , the side being opposite to the side closer to the second path  46  (on the right side of the vertically upper portion of the rotation center). This is, however, not the only possible structure. For example, the accumulation space  75  may be disposed in only the area on the side of the vertically upper portion of the rotation center of the mixing auger  90 , closer to the second path  46  (on the left side of the vertically upper portion of the rotation center). 
     In the present exemplary embodiment, the accumulation space  75  extends from the second path  46  upstream in the rotation direction of the mixing shaft  98 . This is, however, not the only possible structure. For example, the developer G shifted upward from the mixture path  32 C may be formed in the accumulation space  75  only to the downstream side in the rotation direction of the mixing shaft  98  from the second path  46 . 
     In the present exemplary embodiment, as illustrated in  FIG. 5 , the supporter  70  that supports the rotary roller  50  and that includes the second path  46  and the accumulation space  75  is separate from the housing  32  including the mixture path  32 C therein. This is, however, not the only possible structure. For example, the rotary roller  50  may be supported by the housing  32 , and the second path  46  and the accumulation space  75  may be formed in the housing  32 . 
     The present disclosure is not limited to the above-described exemplary embodiments, and may be modified, changed, or improved in various manners within the scope not departing from the gist of the disclosure. For example, any of the above-described modification examples may be appropriately combined with another. 
     The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure 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 disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.