Patent Publication Number: US-8983358-B2

Title: Developer storage body, developer collecting apparatus and image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a developer storage body used in an electrophotographic process, and also relates to a developer collecting apparatus and an image forming apparatus having the developer storage body. 
     An electrophotographic image forming apparatus includes a developer storage body for storing a developer (for example, a waste developer). The developer storage body is elongated, and a receiving opening is provided at an end portion of the developer storage body in a longitudinal direction. A detection member is provided in the vicinity of the receiving opening for detecting that the developer storage body is filled with the developer (see, for example, Japanese Laid-open Patent Publication No. 2011-95518). 
     In this regard, there are cases where a sufficient amount of the developer is not stored in the developer storage body. Therefore, there is a demand for increasing an amount of the developer stored in the developer storage body. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is intended to increase an amount of a developer stored in a developer storage body. 
     According to an aspect of the present invention, there is provided a developer storage body including a developer storage portion configured to store a developer and having a first end portion and a second end portion opposite to each other, and a developer ejecting portion provided in the developer storage portion and located closer to the first end portion than to the second end portion. The developer ejecting portion is configured to eject the developer into the developer storage portion. The developer storage body further includes a developer pushing portion configured to push the developer ejected into the developer storage portion from the developer ejecting portion toward the second end portion. The developer storage body further includes a developer detecting portion provided in the developer storage portion and located closer to the second end portion than to the first end portion. 
     With such a configuration, it becomes possible to increase an amount of the developer in the developer storage container. 
     According to another aspect of the present invention, there is provided a developer collecting apparatus including a developer storage portion configured to store a developer and having a first end portion and a second end portion opposite to each other, a developer ejecting portion provided in the developer storage portion and located closer to the first end portion than to the second end portion, a developer pushing portion configured to push the developer supplied into the developer storage portion from the developer ejecting portion toward the second end portion, and a developer detecting portion provided in the developer storage portion and located closer to the second end portion than to the first end portion. 
     According to yet another aspect of the present invention, there is provided an image forming apparatus including the above described develop storage body. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific embodiments, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the attached drawings: 
         FIG. 1  is a schematic sectional view showing a configuration of an electrophotographic printer as an image forming apparatus according to the first embodiment of the present invention; 
         FIG. 2  is a perspective view showing a developing device in which developing units according to the first embodiment are integrated; 
         FIG. 3  is a perspective view showing a waste toner collecting container and a black toner cartridge according to the first embodiment; 
         FIG. 4  is a perspective view showing the developing device to which the toner cartridges are mounted according to the first embodiment; 
         FIG. 5  is a partially cut-away perspective view showing the waste toner collecting container according to the first embodiment; 
         FIG. 6  is an enlarged view showing the vicinity of a waste toner receiving opening of the waste toner collecting container according to the first embodiment; 
         FIG. 7  is an enlarged view showing the vicinity of a driving portion of a waste toner full detection bar of the waste toner collecting container according to the first embodiment; 
         FIG. 8  is a sectional view showing an internal configuration of the waste toner collecting container according to the first embodiment; 
         FIG. 9A  is a perspective view showing the waste toner full detection bar, a driving gear and a waste toner full detection member according to the first embodiment; 
         FIG. 9B  is an enlarged perspective view showing a part encircled by a circle B in  FIG. 9A ; 
         FIGS. 10A and 10B  are a front view and an exploded perspective view showing a coupling portion of the waste toner full detection bar, the driving gear and the waste toner full detection member according to the first embodiment; 
         FIG. 11  is a sectional view showing a manner in which the waste toner is conveyed and accumulated in the waste toner collecting container according to the first embodiment; 
         FIG. 12  is a schematic view showing an operation to detect a waste toner full state according to the first embodiment; 
         FIG. 13  is a schematic view showing the operation to detect the waste toner full state according to the first embodiment; 
         FIG. 14  is a schematic view showing the operation to detect the waste toner full state according to the first embodiment; 
         FIG. 15  is a schematic view showing the operation to detect the waste toner full state according to the first embodiment; 
         FIG. 16A  is a timing chart showing an output of a detection sensor when the waste toner is not yet accumulated to a position of a crank portion according to the first embodiment; 
         FIG. 16B  is a timing chart showing the output of the detection sensor when the waste toner is accumulated to the position of the crank portion according to the first embodiment; 
         FIG. 17  is a partially cut-away perspective view showing a waste toner collecting container according to the second embodiment of the present invention; 
         FIG. 18  is an enlarged view showing the vicinity of a waste toner receiving opening of the waste toner collecting container according to the second embodiment; 
         FIG. 19  is an enlarged view showing the vicinity of a waste toner full detection bar of the waste toner collecting container according to the second embodiment; 
         FIG. 20  is a sectional view showing an internal configuration of the waste toner collecting container according to the second embodiment; 
         FIG. 21  is a sectional view showing a manner in which the waste toner is conveyed and accumulated in the waste toner collecting container according to the second embodiment; 
         FIG. 22  is an enlarged view showing the vicinity of a driving portion of a waste toner full detection bar of a waste toner collecting container according to the third embodiment of the present invention; 
         FIG. 23  is a sectional view showing an internal configuration of the waste toner collecting container according to the third embodiment; 
         FIG. 24  is a sectional view showing a manner in which the waste toner is conveyed and accumulated in the waste toner collecting container according to the third embodiment; 
         FIG. 25  is a perspective view showing a waste toner collecting container and a toner cartridge according to the fourth embodiment of the present invention; 
         FIG. 26  is a partially cut-away perspective view showing the waste toner collecting container according to the fourth embodiment; 
         FIG. 27  is a sectional view showing a manner in which the waste toner is conveyed and accumulated in the waste toner collecting container according to the fourth embodiment, and 
         FIG. 28  is a partially cut-away perspective view showing the waste toner collecting container according to a modification of the fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, embodiments of the present invention will be described with reference to drawings. The drawings are provided for illustrative purpose and are not intended to limit the scope of the present invention. 
     First Embodiment 
     Hereinafter, the first embodiment of the present invention will be described.  FIG. 1  is a schematic sectional view showing an electrophotographic printer  1  as an image forming apparatus according to the first embodiment of the present invention. 
     As shown in  FIG. 1 , the electrophotographic printer (hereinafter, referred to as a printer)  1  includes a medium feeding unit  6  configured to store media (such as printing sheets) and to feed the media. The printer  1  further includes developing units (i.e., process units)  2   k ,  2   c ,  2   m  and  2   y  which are arranged along a feeding path of the medium fed by the medium feeding unit  6 . LED heads (i.e., exposure units)  5   k ,  5   c ,  5   m  and  5   y  are provided on one side (for example, an upper side) of the developing units  2   k ,  2   c ,  2   m  and  2   y  so as to face the developing units  2   k ,  2   c ,  2   m  and  2   y . A transfer unit  4  is provided on the other side (for example, a lower side) of the developing units  2   k ,  2   c ,  2   m  and  2   y  so as to face the developing units  2   k ,  2   c ,  2   m  and  2   y . A fixing unit  7  is provided downstream of the developing units  2   k ,  2   c ,  2   m  and  2   y  in a feeding direction of the medium. 
     The medium feeding unit  6  includes a medium cassette in which a stack of the media is stored, and a medium feeding mechanism that feeds the media one by one from the medium cassette. The medium feeding mechanism includes, for example, a pickup roller, a feed roller, a registration roller and the like, but detailed descriptions thereof will be omitted. The medium fed from the medium feeding unit  6  proceeds in a direction shown by an arrow A (for example, from the right to the left in  FIG. 1 ) along the feeding path provided in the printer  1 . 
     The developing units  2   k ,  2   c ,  2   m  and  2   y  are configured to form toner images (i.e., developer images) of black, cyan, magenta and yellow. The developing units  2   k ,  2   c ,  2   m  and  2   y  are arranged on a line along the feeding path of the medium (for example, from the right to the left in  FIG. 1 ). 
     The LED (Light Emitting Diode) heads  5   k ,  5   c ,  5   m  and  5   y  are configured to emit light to thereby expose surfaces of respective photosensitive drums (described later) of the developing units  2   k ,  2   c ,  2   m  and  2   y  to form latent images. The LED heads  5   k ,  5   c ,  5   m  and  5   y  are mounted to, for example, a top cover of the printer  1 . 
     The developing units  2   k ,  2   c ,  2   m  and  2   y  include photosensitive drums  21   k ,  21   c ,  21   m  and  21   y  as image bearing bodies, charging rollers  22   k ,  22   c ,  22   m  and  22   y  as charging members, developing rollers  23   k ,  23   c ,  23   m  and  23   y  as developer bearing bodies, developing blades  24   k ,  24   c ,  24   m  and  24   y  as developer layer forming members, and supplying rollers  25   k ,  25   c ,  25   m  and  25   y  as supplying members. 
     The photosensitive drums  21   k ,  21   c ,  21   m  and  21   y  are configured to bear latent images on surfaces thereof. The charging rollers  22   k ,  22   c ,  22   m  and  22   y  are configured to uniformly charge surfaces of the photosensitive drums  21   k ,  21   c ,  21   m  and  21   y . The developing rollers  23   k ,  23   c ,  23   m  and  23   y  are configured to develop latent images on the surfaces of the photosensitive drums  21   k ,  21   c ,  21   m  and  21   y  formed by the LED heads  5   k ,  5   c ,  5   m  and  5   y . The developing blades  24   k ,  24   c ,  24   m , and  24   y  are configured to form toner layers (i.e., developer layers) on the surfaces of the photosensitive drums  21   k ,  21   c ,  21   m  and  21   y . The supplying rollers  25   k ,  25   c ,  25   m  and  25   y  are configured to supply the toner to the developing rollers  23   k ,  23   c ,  23   m  and  23   y.    
     The developing units  2   k ,  2   c ,  2   m  and  2   y  further include cleaning blades  26   k ,  26   c ,  26   m  and  26   y  as cleaning members and first conveying mechanisms  27   k ,  27   c ,  27   m  and  27   y  as first conveying units. The cleaning blades  26   k ,  26   c ,  26   m  and  26   y  are configured to remove residual toner on the surfaces of the photosensitive drums  21   k ,  21   c ,  21   m  and  21   y  which has not been transferred to the medium. The first conveying mechanisms  27   k ,  27   c ,  27   m  and  27   y  are configured to convey the toner (i.e., a waste toner) removed by the cleaning blades  26   k ,  26   c ,  26   m  and  26   y.    
     The first conveying mechanisms  27   k ,  27   c ,  27   m  and  27   y  have, for example, spirals in the form of coils. The first conveying mechanisms  27   k ,  27   c ,  27   m  and  27   y  receive the waste toner removed by the cleaning blades  26   k ,  26   c ,  26   m  and  26   y  from the surfaces of the photosensitive drums  21   k ,  21   c ,  21   m  and  21   y , and convey the waste toner in an axial direction of the photosensitive drums  21   k ,  21   c ,  21   m  and  21   y.    
     Toner cartridges  3   k ,  3   c ,  3   m  and  3   y  (i.e., developer cartridges) are detachably mounted to upper parts of the developing units  2   k ,  2   c ,  2   m  and  2   y . The toner cartridges  3   k ,  3   c ,  3   m  and  3   y  are configured to store toner (i.e., developer) of respective colors. The toner cartridges  3   k ,  3   c ,  3   m  and  3   y  include toner storage portions (i.e., developer storage containers)  31   k ,  31   c ,  31   m  and  31   y  for storing unused (i.e., fresh) toner. 
     The transfer unit  4  includes a transfer belt  41 , and includes a driving roller  42  and a driven roller  43  around which the transfer belt  41  is stretched. The transfer unit  4  further includes transfer rollers  40   k ,  40   c ,  40   m  and  40   y  (i.e., transfer members) provided so as to face photosensitive drums  21   k ,  21   c ,  21   m  and  21   y.    
     The transfer belt  41  moves in a direction as shown by the arrow A by a rotation of the driving roller  42 . The transfer belt  41  absorbs and holds the medium at a surface thereof, and feeds the medium in the direction shown by the arrow A. The driven roller  43  applies a predetermined tension to the transfer belt  41 . The transfer rollers  40   k ,  40   c ,  40   m  and  40   y  are applied with predetermined transfer voltages, and transfer toner images from the surfaces of the photosensitive drums  21   k ,  21   c ,  21   m  and  21   y  to a surface of the medium held on the transfer belt  41 . 
     The fixing unit  7  includes, for example, a fixing roller  71  having an internal heat source and a pressure roller  72  pressed against the fixing roller  71 . The fixing roller  71  and the pressure roller  72  are configured to apply heat and pressure to the medium with the toner image transferred thereto, so as to fix the toner image to the medium. Although not shown in  FIG. 1 , an ejection mechanism is provided downstream of the fixing unit  7  for ejecting the medium with the fixed toner image. 
       FIG. 2  is a perspective view showing a developing device (i.e., a process unit assembly)  2  in which the developing units  2   k ,  2   c ,  2   m  and  2   y  are integrated.  FIG. 3  is a perspective view showing a waste toner collecting container  32  and the black toner cartridge  3   k .  FIG. 4  is a perspective view showing the developing device  2  with toner cartridges  3   k ,  3   c ,  3   m  and  3   y  mounted to developing units  2   k ,  2   c ,  2   m  and  2   y.    
     As shown in  FIG. 2 , the developing units  2   k ,  2   c ,  2   m  and  2   y  are arranged at equal intervals in such a manner that longitudinal directions of the developing units  2   k ,  2   c ,  2   m  and  2   y  (i.e., axial directions of the photosensitive drums  21   k ,  21   c ,  21   m  and  21   y ) are parallel to each other. The developing units  2   k ,  2   c ,  2   m  and  2   y  are integrally held by a first side frame  51  and a second side frame  52  both of which have high rigidity. The first side frame  51  and the second side frame  52  are provided on both sides of the developing units  2   k ,  2   c ,  2   m  and  2   y  in the longitudinal direction thereof. 
     The first side frame  51  includes a second conveying mechanism  28  as a second conveying unit. The second conveying mechanism  28  is connected to the first conveying mechanisms  27   k ,  27   c ,  27   m  and  27   y  ( FIG. 1 ) of the developing units  2   k ,  2   c ,  2   m  and  2   y . The second conveying mechanism  28  is configured to receive the waste toner from the first conveying mechanisms  27   k ,  27   c ,  27   m  and  27   y , and to convey the waste toner in a direction shown by an arrow C. 
     A waste toner collecting container  32  ( FIGS. 3 and 4 ) as a developer collecting apparatus (i.e., a developer storage body) is provided upstream of the developing units  2   k ,  2   c ,  2   m  and  2   y  in an arranging direction of the developing units  2   k ,  2   c ,  2   m  and  2   y . In other words, the waste toner collecting container  32  is disposed adjacent to the black developing unit  2   k . The first side frame  51  includes a waste toner ejecting portion  29  ( FIG. 2 ) as a developer ejecting portion. The waste toner ejecting portion  29  is formed to connect the second conveying mechanism  28  and a waste toner receiving opening  720  ( FIG. 5 ) of the waste toner collecting container  32 . 
     As shown in  FIG. 3 , the waste toner collecting container  32  is mounted to the black toner cartridge  3   k . Generally, black toner is used more frequently than other colors, and therefore the black toner cartridge  3   k  is most frequently replaced. For this reason, the waste toner collecting container  32  is mounted to the black toner cartridge  3   k  so that the waste toner collecting container  32  is replaced at an early stage before the waste toner collecting container  32  is filled with the waste toner. 
     However, the present invention is not limited to such a configuration. For example, the waste toner collecting container  32  can be mounted to any of the toner cartridges  3   c ,  3   m  and  3   y  other than black toner cartridge  3   k . Further, the waste toner collecting container  32  can be configured separately from the toner cartridges  3   k ,  3   c ,  3   m  and  3   y . In other words, the waste toner collecting container  32  can be mounted to and detached from the developing device  2  separately (independently) from the toner cartridges  3   k ,  3   c ,  3   m  and  3   y.    
     In a state where the toner cartridges  3   k ,  3   c ,  3   m  and  3   y  are mounted to the developing device  2  as shown in  FIG. 4 , the waste toner ejecting portion  29  of the first side frame  51  is connected to the waste toner receiving opening  720  ( FIG. 5 ) of the waste toner collecting container  32  mounted to the black toner cartridge  3   k.    
     The developing device  2  and the toner cartridges  3   k ,  3   c ,  3   m  and  3   y  are replaceable units, and can be replaced when the toner is consumed or when a lifetime of any component expires. 
     Referring back to  FIG. 2 , toner receiving openings are formed on upper parts of the developing units  2   k ,  2   c ,  2   m  and  2   y . The toner receiving openings are provided for receiving the toner from the toner cartridges  3   k ,  3   c ,  3   m  and  3   y . The toner receiving openings are opened and closed by shutter members  53   k ,  53   c ,  53   m  and  53   y.    
       FIG. 5  is a partially cut-away perspective view showing the waste toner collecting container  32  according to the first embodiment.  FIG. 6  is an enlarged view showing the vicinity of the waste toner receiving opening  720  of the waste toner collecting container  32 .  FIG. 7  is an enlarged view showing the vicinity of a driving portion of a waste toner full detection bar  704  of the waste toner collecting container  32 .  FIG. 8  is a sectional view showing an internal configuration of the waste toner collecting container  32 . 
     As shown in  FIGS. 5 through 8 , the waste toner collecting container  32  is elongated in the longitudinal direction of the developing units  2   k ,  2   c ,  2   m  and  2   y  ( FIG. 2 ). The waste toner collecting container  32  includes an outer frame  701  and a side plate  702 . The outer frame  701  is an outer wall (i.e., enclosure) of the waste toner collecting container  32 . The side plate  702  is a side wall of the waste toner collecting container  32  on the same side as the second side frame  52  ( FIG. 2 ). The outer frame  701  and the side plate  702  constitute a waste toner storage portion (i.e., a developer storage portion)  40  in which a waste toner is stored. 
     The outer frame  701  has the above described waste toner receiving opening  720  as a developer receiving portion for receiving the waste toner. The waste toner receiving opening  720  is connected to the waste toner ejecting portion  29  of the first side frame  51  shown in  FIG. 2 . Through the waste toner ejecting portion  29 , the waste toner receiving opening  720  receives the waste toner having been conveyed by the second conveying mechanism  28 . The waste toner receiving opening  720  is disposed on an end portion (i.e., a first end portion) of the waste toner collecting container  32  in the longitudinal direction. 
     A waste toner conveying spiral  703  (i.e., a developer conveying unit) is provided in the waste toner collecting container  32 . The waste toner conveying spiral  703  is configured to convey the waste toner (which is collected via the waste toner receiving opening  720 ) in a direction toward the side plate  702 . The waste toner conveying spiral  703  extends from a portion below the waste toner receiving opening  720  to reach the side plate  702 . The waste toner conveying spiral  703  is supported so as to be rotatable about a rotation axis  703   a , i.e., a center axis of the waste toner conveying spiral  703 . A waste toner full detection bar  704  (i.e., a rotation member or a developer detecting unit) is provided above the waste toner conveying spiral  703 . 
     A receiving opening shutter  705  and a shutter supporting portion  721  are formed on the outer frame  701 . The receiving opening shutter  705  is configured to open and close the waste toner receiving opening  720 . The shutter supporting portion  721  supports the receiving opening shutter  705  allowing the receiving opening shutter  705  to move. Further, a shutter seal member  706  is provided between the receiving opening shutter  705  and the shutter supporting portion  721 . The shutter seal member  706  seals between the receiving opening shutter  705  and the shutter supporting portion  721 . A spring  707  ( FIG. 6 ) as a shutter biasing member is provided for biasing the receiving opening shutter  705  in a direction in which the receiving opening shutter  705  closes the waste toner receiving opening  720 . 
     A conveying path  722  is provided below the waste toner receiving opening  720 . The conveying path  722  has a substantially cylindrical shape, and is hereinafter referred to as a cylindrical conveying path  722 . The cylindrical conveying path  722  is configured to guide the waste toner (fallen from the waste toner receiving opening  720 ) in a conveying direction, i.e., in a direction in which the waste toner conveying spiral  703  conveys the waste toner. A toner exit (i.e., a developer ejection opening)  722   a  is provided at an end of the cylindrical conveying path  722 . The waste toner is ejected from the cylindrical conveying path  722  into the waste toner storage portion  40  via the toner exit  722   a.    
     A part of the waste toner collecting container  32  including the waste toner receiving opening  720  and the cylindrical conveying path  722  is referred to as a toner introducing portion S (i.e., a developer ejecting portion). The waste toner is ejected from the toner introducing portion S into the waste toner storage portion  40 . 
     An end portion of the waste toner collecting container  32  where the waste toner receiving opening  720  is disposed (i.e., on the waste toner receiving opening  720  side) is referred to as a first end portion. Another end portion of the waste toner collecting container  32  where the side plate  702  is disposed (i.e., on the side plate  702  side) is referred to as a second end portion. 
     Further, a side of the waste toner collecting container  32  where the waste toner receiving opening  720  is disposed is referred to as a conveyance starting side. Another side of the waste toner collecting container  32  where the side plate  702  is disposed is referred to as a conveyance termination side. 
     The waste toner conveying spiral  703  includes a gear engaging portion  726 . The gear engaging portion  726  is provided at an end portion of the waste toner conveying spiral  703  located closer to the waste toner receiving opening  720 . The gear engaging portion  726  engages a spiral driving gear  708  for rotating the waste toner conveying spiral  703 . A rotation of the spiral driving gear  708  causes a rotation of the waste toner conveying spiral  703 . A spiral shaft seal member  710  is provided on a shaft portion of the waste toner conveying spiral  703 . The spiral shaft seal member  710  seals between the shaft portion of the waste toner conveying spiral  703  and the outer frame  701 . 
     Claws  723  are provided at an end portion of the outer frame  701  located closer to the side plate  702 . The claws  723  are formed to engage respective portions of the side plate  702 . The side plate  702  has a wall surface  702   a  which forms an end portion of the waste toner storage portion  40  on the conveyance termination side. 
     As shown in  FIG. 7 , a waste toner full detection member  711 , a detection member cover  712  and a chattering prevention film  713  are provided on an outer side of the side plate  702 . The waste toner full detection member  711  (i.e., a detecting member) is configured to detect an accumulation state of the waste toner in the waste toner storage portion  40 . The detection member cover  712  is formed to cover the waste toner full detection member  711 . A cover mounting portion  725  is formed on the outer side of the side plate  702 . The detection member cover  712  is mounted to the cover mounting portion  725 . A gear housing cover  1000  is mounted to the side plate  702  by press-fitting. The gear housing cover  1000  is formed to cover driving gears described later. 
     A driving gear  714 , a reduction gear  715  and another reduction gear  716  are rotatably provided on an inner side of the side plate  702 . The driving gear  714  is provided for rotating the waste toner full detection bar  704 . The reduction gear  715  engages the driving gear  714 . The reduction gear  716  engages the reduction gear  715 . 
     The driving gear  714  and the reduction gears  715  and  716  (i.e., driving gears) are housed in a gear housing  724  formed on the side plate  702 , and are covered by the gear housing cover  1000  from outside. The driving gear  714 , the reduction gears  715  and  716  are rotatably supported by the gear housing cover  1000 . Shaft portions of the waste toner full detection bar  704  and the waste toner conveying spiral  703  penetrate a wall portion of the gear housing portion  724 . 
     As shown in  FIG. 8 , the gear housing  724  includes a first wall surface  724   a , a second wall surface  724   b  and a third wall surface  724   c . The second wall surface  724   b  supports the shaft portion of the waste toner full detection bar  704 . The third wall surface  724   c  supports the shaft portion of the waste toner conveying spiral  703 . The wall surfaces  724   a ,  724   b  and  724   c  protrude inwardly into the waste toner storage portion  40  with respect to the wall surface  702   a  of the side plate  702 . Protruding amounts of the wall surfaces  724   a ,  724   b  and  724   c  are different among one another. In other words, the waste toner storage portion  40  has an indented shape in the vicinity of the wall surfaces  724   a ,  724   b  and  724   c.    
     Referring back to  FIG. 7 , a seal member  717  is provided on the shaft portion of the waste toner full detection bar  704 . The seal member  717  seals between the shaft portion of the waste toner full detection bar  704  and the wall portion of the gear housing portion  724 . A seal member  718  is provided on the shaft portion of the waste toner conveying spiral  703 . The seal member  718  seals between the shaft portion of the waste toner conveying spiral  703  and the wall portion of the gear housing portion  724 . 
     A gear portion  727  is provided at an end portion of the waste toner conveying spiral  703  on the conveyance termination side (i.e., located closer to the side plate  702 ). The gear portion  727  transmits the rotation of the waste toner conveying spiral  703  to the driving gears (i.e., the driving gear  714  and the reduction gears  715  and  716 ) for the waste toner full detection bar  704 . 
     As shown in  FIG. 8 , the waste toner conveying spiral  703  has a first spiral portion  803  as a first portion or a developer pushing portion. The first spiral portion  803  extends a predetermined area of the waste toner conveying spiral  703  on the conveyance starting side. The waste toner conveying spiral  703  further has a second spiral portion  804  as a second portion. The second spiral portion  804  is located downstream of the first spiral portion  803  in the conveying direction of the waste toner. 
     The first spiral portion  803  extends from the vicinity of the end portion of the waste toner conveying spiral  703  on the conveyance starting side to reach a predetermined position (i.e., a terminating position) A. The terminating position A of the first spiral portion  803  is shifted inwardly into the waste toner storage portion  40  with respect to a position B of the toner exit  722   a  of the cylindrical conveying path  722  by a distance L 1 . In a particular example, the distance L 1  is in a range from 10 mm to 20 mm, which corresponds to one pitch or two pitches of a spiral blade of the first spiral portion  803 . 
     The first spiral portion  803  includes a rotation shaft (i.e., a first rotation shaft) and a spiral blade (i.e., a first spiral blade or a conveying blade) formed thereon. For example, the spiral blade of the first spiral portion  803  has a height in a range from 4 mm to 5 mm. The second spiral portion  804  includes a rotation shaft (i.e., a second rotation shaft) and a spiral blade (i.e., a second spiral blade) formed thereon. The spiral blade of the second spiral portion  804  has a height which is lower than the height of the spiral blade of the first spiral portion  803 . For example, the spiral blade of the second spiral portion  804  has the height of approximately 1 mm. The spiral blade of the second spiral portion  804  hardly contributes to conveyance of the waste toner. 
     In this regard, the height of the spiral blade of the first spiral portion  803  corresponds to a protruding amount (i.e., a first protruding amount) of the spiral blade protruding from the rotation shaft of the first spiral portion  803 . Similarly, the height of the spiral blade of the second spiral portion  804  corresponds to a protruding amount (i.e., a second protruding amount) of the spiral blade protruding from the rotation shaft of the second spiral portion  804 . The second protruding amount is less than the first protruding amount. 
     The waste toner conveying spiral  703  is formed of resin material. The waste toner conveying spiral  703  receives a rotational force at the gear engaging portion  726 , and transmits the rotational force to the waste toner full detection bar  704  via the gear portion  727 . Since the waste toner conveying spiral  703  has the second spiral portion  804  that hardly contributes to the conveyance of the waste toner, a load (i.e., a rotational load) on the waste toner conveying spiral  703  can be reduced. Therefore, it is ensured that the waste toner conveying spiral  703  has sufficient torsion strength. 
     The waste toner full detection bar  704  includes a straight portion  742  extending in a direction substantially parallel to the rotation axis  703   a  of the waste toner conveying spiral  703 . The waste toner full detection bar  704  further includes a crank portion  741  as a developer detecting portion provided on the conveyance termination side with respect to the straight portion  742 . The waste toner full detection bar  704  is supported so as to be rotatable about a rotation axis  704   a , i.e., a center axis of the straight portion  742 . 
     The crank portion  741  includes an arm portion  741   a  extending radially outward from the straight portion  742 . In a particular example, the arm portion  741   a  extends obliquely with respect to the straight portion  742 . The crank portion  741  further includes a parallel portion  741   b  extending in a direction substantially parallel to the straight portion  742  from an end (i.e., a terminating position) of the arm portion  741   a . The crank portion  741  further includes another arm portion  741   c  extending toward the rotation axis  704   a  from an end (i.e., a terminating position) of the parallel portion  741   b . In a particular example, the arm portion  741   c  extends obliquely with respect to the straight portion  742 . 
     A pushing area α, an accumulation area β and a detection area γ are provided in the waste toner storage portion  40 . The pushing area α is an area in which the first spiral portion  803  of the waste toner conveying spiral  703  pushes the waste toner. The detection area γ is an area in which the crank portion  741  of the waste toner full detection bar  704  detects the waste toner. The accumulation area β is provided between the pushing area α and the detection area γ. The accumulation area β is an area in which the waste toner is accumulated. A length of the crank portion  741  (i.e., a length of the detection area γ) is smaller than or equal to a half (½) of a length of the second spiral portion  804  of the waste toner conveying spiral  703  (i.e., a sum of the lengths of the accumulation area β and the detection area γ). 
     The shaft portion of the waste toner full detection bar  704  penetrates the side plate  702 . A hook portion  729  (i.e., a rotation transmitting portion) is provided at a tip portion of the shaft portion of the waste toner full detection bar  704 . The hook portion  729  receives a rotation transmitted from the waste toner full detection member  711 . 
     As described later, the waste toner full detection bar  704  is rotatable about the rotation axis  704   a . When the crank portion  741  rotates from a bottom dead point (i.e., a lowermost point) to a top dead point (i.e., an uppermost point), the waste toner full detection bar  704  rotates together with the waste toner full detection member  711  by a rotational force transmitted via the driving gear  714 . However, after the crank portion  741  passes the top dead point, the waste toner full detection bar  704  rotates to the bottom dead point by gravity due to a weight of the crank portion  741  together with the waste toner full detection member  711 . 
     The crank portion  741  of the waste toner full detection bar  704  is provided on the conveyance termination side (i.e., on the side where the side plate  702  is disposed). When the waste toner accumulated in the waste toner storage portion  40  reaches the vicinity of a waste toner full detecting position C ( FIG. 8 ) at an upstream end of the crank portion  741  in the conveying direction of the waste toner, the crank portion  741  contacts the waste toner. Therefore, the crank portion  741  is subjected to rotational resistance, which causes a change in a state of the rotation of the waste toner full detection bar  704  due to the weight of the crank portion  741 . 
     In  FIG. 8 , L 2  represents a distance from the position B (i.e., an exit position) of the toner exit  722   a  of the cylindrical conveying path  722  to a position D of the wall surface  702   a  of the side plate  702 . L 3  represents a distance from the exit position B of the cylindrical conveying path  722  to the waste toner full detecting position C. It is preferred that the distance L 3  is longer than a half (½) of the distance L 2  (i.e., L 3 &gt;½×L 2 ). Further, it is preferred that the crank portion  741  has a sufficient length (i.e., a crank length) so that the rotation of the waste toner full detection bar  704  (about the rotation axis  704   a ) is caused by gravity due to the weight of the crank portion  741 . In a particular example, the distance L 3  is approximately set to ⅔ of the distance L 2  (i.e., L 3 ≅⅔×L 2 ). 
     Here, the waste toner full detecting position C is defined as an approximately intermediate position between a starting position E of the arm portion  741   a  (i.e., a border between the straight portion  742  and the arm portion  741   a ) and a terminating position F of the arm portion  741   a  (i.e., a border between the arm portion  741   a  and the parallel portion  741   b ). In other words, when a length of the arm portion  741   a  in the direction of the rotation axis  704   a  is represented by L 4 , the waste toner full detecting position C is so determined that a distance from the starting position E of the arm portion  741   a  to the waste toner full detecting position C is approximately the same as a half (½) of the length L 4  (i.e., ½×L 4 ). 
     In this regard, the waste toner full detecting position C can alternatively be determined as the starting position E or the terminating position F of the arm portion  741   a  in consideration of detection accuracy of the waste toner. Although the arm portions  741   a  and  741   c  are inclined with respect to the rotation axis  704   a  as shown in  FIG. 8 , it is also possible that the arm portions  741   a  and  741   c  are perpendicular to the rotation axis  704   a . In such a case, the length L 4  is 0. 
     The hook portion  729  of the waste toner full detection bar  704  is formed by bending the tip portion of the waste toner full detection bar  704  at an angle with respect to the rotation axis  704   a . The hook portion  729  engages the waste toner full detection member  711 . With an engagement between the hook portion  729  and the waste toner full detection member  711 , the waste toner full detection member  711  and the waste toner full detection bar  704  rotate continuously together with each other. 
     The waste toner full detection bar  704  has a light reflecting portion  730  ( FIG. 7 ) that reflects light emitted by a detection sensor  760  ( FIG. 3 ) provided on a main body of the printer  1 . The above described detection member cover  712  is formed to cover the waste toner full detection member  711 , and has a substantially cylindrical shape. An opening  734  is formed on a part of the detection member cover  712  for allowing light emitted by the detection sensor  760  to pass. The waste toner full detection member  711  has a rib  731  that contacts the chattering prevention film  713  after the waste toner full detection member  711  rotates by gravity due to the weight of the crank portion  741 . 
     The waste toner full detection member  711  has a rotation transmission rib  732  and a detection bar engaging portion  733 . The rotation transmission rib  732  is configured to receive a rotational force transmitted from the driving gear  714 . The detection bar engaging portion  733  is configured to engage the hook  729  to thereby transmit the rotational force to the waste toner full detection bar  704 . 
     The detection sensor  760  shown in  FIG. 3  is a reflective-type sensor, and has a light emitting portion and a light receiving portion. The light emitting portion of the detection sensor  760  emits light. When the light receiving portion of the detection sensor  760  receives light reflected by the light reflecting portion  730 , the detection sensor  760  outputs “ON” signal. When the light receiving portion of the detection sensor  760  does not receive light, the detection sensor  760  outputs “OFF” signal. 
       FIG. 9A  is a perspective view showing the waste toner full detection bar  704 , the driving gear  714  and the waste toner full detection member  711 .  FIG. 9B  is an enlarged perspective view showing a part encircled by a circle B in  FIG. 9A .  FIGS. 10A and 10B  are a front view and an exploded perspective view showing a coupling portion of the waste toner full detection bar  704 , the driving gear  714  and the waste toner full detection member  711 . 
     As shown in  FIGS. 9A and 9B , the waste toner full detection bar  704  penetrates the driving gear  714 . The tip portion of the waste toner full detection bar  704  penetrating the driving gear  714  is bent, and forms the hook portion  729 . As shown in  FIG. 9B , the waste toner full detection member  711  has the detection bar engaging portion  733  having a concave portion  733   a . The hook  729  of the waste toner full detection bar  704  engages the concave portion  733   a  of the detection bar engaging portion  733 . With an engagement of the hook  729  and the concave portion  733   a , the waste toner full detection member  711  and waste toner full detection bar  704  rotate together with each other. 
     As shown in  FIGS. 10A and 10B , the driving gear  714  has a coaxial annular portion  751  that slidably engages an outer circumference of a shaft receiving portion  1001  of the gear housing cover  1000 . The driving gear  714  has a rotation transmission rib  752  inside the annular portion  751 . The waste toner full detection member  711  has a cylindrical portion  711   a  and a flange portion  711   b . The cylindrical portion  711   a  is coaxial with the annular portion  751  of the driving gear  714 , and slidably engages an inner circumference of the shaft receiving portion  1001  of the gear housing cover  1000 . The flange portion  711   b  contacts a side surface of the gear housing cover  1000 . The cylindrical portion  711   a  has a rotation transmission rib  732 . 
     The rotation transmission rib  732  contacts the rotation transmission rib  752  of the driving gear  714  when the driving gear  714  rotates in a direction shown by an arrow “a” shown in  FIG. 10B  (i.e., when the rotation transmission rib  752  rotates in a direction shown by an arrow “b”). 
     When the driving gear  714  rotates in a direction shown by the arrow “a”, the rotation transmission rib  752  of the driving gear  714  contacts the rotation transmission rib  732  and pushes the rotation transmission rib  732  in the direction shown by the arrow “b”. Therefore, a rotation of the driving gear  714  is transmitted to the waste toner full detection member  711 , and the waste toner full detection member  711  rotates in the same direction as the driving gear  714 . Further, the waste toner full detection bar  704  rotates in the same direction as the waste toner full detection member  711  by the engagement between the hook portion  729  and the concave portion  733   a . That is, the waste toner full detection member  711  and the waste toner full detection bar  704  rotate together with each other. 
     During the rotation of the waste toner full detection member  711  and the waste toner full detection bar  704 , when the crank portion  741  passes the top dead point (i.e., the uppermost point of its rotation range), the rotation transmission rib  732  of the waste toner full detection member  711  separates from the rotation transmission rib  752  of the driving gear  714 . Then, the waste toner full detection bar  704  and the waste toner full detection member  711  rotate downward by gravity due to the weight of the crank portion  741 . 
     In other words, the waste toner full detection bar  704  and the waste toner full detection member  711  are configured to freely rotate downward from the top dead point by gravity due to the weight of the crank portion.  741 . In this embodiment, an accumulation state of the waste toner is determined based on a rotational state of the waste toner full detection bar  704  and the waste toner full detection member  711  while the waste toner full detection bar  704  and the waste toner full detection member  711  rotate downward by gravity. 
     A basic operation of the printer  1  according to the first embodiment will be described with reference to  FIG. 1 . The media (for example, the printing sheets) stored in the medium feeding unit  6  are fed out therefrom one by one, and each medium is fed along the feeding path to reach the transfer unit  4 . Then, the medium is absorbed and held by the transfer belt  41 , and fed by the transfer belt  41  through the developing units  2   k ,  2   c ,  2   m  and  2   y.    
     In the black developing unit  2   k , the black toner replenished by the toner cartridge  3   k  is supplied to the developing roller  23   k  via the supplying roller  25   k . The toner layer with a uniform thickness is formed on the surface of the developing roller  23   k  by the developing blade  24   k . The surface of the photosensitive drum  21   k  is uniformly charged by the charging roller  22   k , and is exposed with light emitted by the LED head  25   k , so that a latent image is formed on the surface of the photosensitive drum  21   k . The latent image is developed with the toner on the surface of the developing roller  23   k , and a black toner image is formed on the surface of the photosensitive drum  21   k . The black toner image is transferred from the surface of the photosensitive drum  21   k  to the surface of the medium on the transfer belt  41  when the medium passes between the photosensitive drum  21   k  and the transfer roller  40   k.    
     Similarly, cyan, magenta and yellow toner images are respectively formed by the developing unit  2   c ,  2   m  and  2   y , and are transferred to the surface of the medium. 
     The medium to which the toner images of the respective colors are transferred is fed by the transfer belt  41  to the fixing unit  7 . The fixing unit  7  applies heat and pressure to the medium so as to fix the toner image to the medium. The medium to which the toner image is fixed is ejected outside the printer  1 , and formation of the toner image on the medium is completed. 
     In the above described process, the toner may remain on the surfaces of the photosensitive drums  21   k ,  21   c ,  21   m  and  21   y . Such a toner is removed by the cleaning blades  26   k ,  26   c ,  26   m  and  26   y . The toner (i.e., the waste toner) removed by the cleaning blades  26   k ,  26   c ,  26   m  and  26   y  is collected by the first conveying mechanism  27   k ,  27   c ,  27   m  and  27   y . The waste toner conveyed by the first conveying mechanism  27   k ,  27   c ,  27   m  and  27   y  is further conveyed by the second conveying mechanism  28  to the waste toner collecting container  32 . 
       FIG. 11  is a sectional view showing a manner in which the waste toner is conveyed and accumulated in the waste toner collecting container  32  according to the first embodiment. As shown in  FIG. 11 , the waste toner having been conveyed by the second conveying mechanism  28  is collected into the waste toner collecting container  32  via the waste toner receiving opening  720 . 
     While the printer  1  is performing the image forming operation, the waste toner conveying spiral  703  keeps rotating. The rotation of the waste toner conveying spiral  703  is transferred to the waste toner full detection member  711  and the waste toner full detection bar  704 , and therefore the waste toner full detection member  711  and the waste toner full detection bar  704  also keep rotating. In this regard, after the crank portion  741  passes the top dead point, the waste toner full detection member  711  and the waste toner full detection bar  704  freely rotate downward to the bottom dead point by gravity due to the weight of the crank portion  741 . 
     As the waste toner conveying spiral  703  rotates, the waste toner is conveyed by the first spiral portion  803  along the cylindrical conveying path  722  in the direction shown by an arrow G. The waste toner is ejected from the cylindrical conveying path  722  via the toner exit  722   a , and is accumulated at the exit position B in a mound shape. The waste toner is accumulated at a height lower than the first spiral portion  803 . The accumulation of the waste toner proceeds in a direction shown by an arrow H. 
     When the accumulated waste toner reaches the terminating position A of the first spiral portion  803  of the waste toner conveying spiral  703 , the waste toner is accumulated in a mound shape beyond the height of the first spiral portion  803 . The accumulation of the waste toner proceeds in a direction shown by an arrow I. 
     As the amount of the waste toner in the waste toner storage portion  40  increases, the straight portion  742  of the rotating waste toner full detection bar  704  is buried in the waste toner. Further, when the accumulated waste toner reaches the waste toner full detecting position C, the crank portion  741  is subjected to rotational resistance, which causes a change in a rotational state of the waste toner full detection bar  704 . The crank portion  741  is disposed in an area of the conveyance termination side of the waste toner storage portion  40  as described above. 
     In this regard, a method for detecting the change in the rotational state of the waste toner full detection bar  704  will be described.  FIGS. 12 through 15  are schematic views showing the waste toner full detection member  711  as seen in a direction shown by an arrow D in  FIG. 8 . 
     The waste toner full detection bar  704  and the waste toner full detection member  711  rotate in the direction shown by the arrow “a” (i.e., counterclockwise) by the rotation of the driving gear  714 . When the crank portion  741  of the waste toner full detection bar  704  is in the bottom dead point of its rotation range, the light reflection portion  730  of the waste toner full detection member  711  is in a top dead point of its rotation range. In this state, the light reflecting portion  730  faces the opening  734  (shown with hatching in  FIGS. 12 through 15 ) of the detection member cover  712  ( FIG. 7 ), and reflects light emitted by the detection sensor  760 . Therefore, the detection sensor  760  outputs “ON” signal. 
     Then, the waste toner full detection bar  704  and the waste toner full detection member  711  rotate in the direction shown by the arrow “a” (i.e., counterclockwise) at a predetermined speed by the rotation of the driving gear  714 , and the crank portion  741  reaches the top dead point as shown in  FIG. 13 . When the crank portion  741  passes the top dead point, the waste toner full detection bar  704  and the waste toner full detection member  711  rotate downward by gravity due to the weight of the crank portion  741 . Therefore, engagement between the rotation transmission rib  732  of the waste toner full detection member  711  and the rotation transmission rib  752  ( FIG. 10B ) of the driving gear  714  is released. 
     In a state where the waste toner is not yet accumulated to a disposition area of the crank portion  741  (i.e., an area in which the crank portion  741  is disposed), the waste toner full detection bar  704  and the waste toner full detection member  711  rotate from the top dead point to the bottom dead point by gravity (due to the weight of the crank portion  741 ) as shown in  FIG. 14 . Then, the driving gear  714  further rotates, and the rotation transmission rib  752  ( FIG. 10B ) of the driving gear  714  again contacts the rotation transmission rib  732  of the waste toner full detection member  711 . Therefore, the waste toner full detection bar  704  and the waste toner full detection member  711  start rotating at the constant speed. 
     In contrast, in a state where the waste toner is accumulated to the disposition area of the crank portion  741  (for example, a height of the crank portion  741 ), the waste toner full detection bar  704  and the waste toner full detection member  711  rotate downward by gravity (due to the weight of the crank portion  741 ) as shown in  FIG. 15 . However, the crank portion  741  is subjected to rotational resistance from the accumulated waste toner T, and therefore the waste toner full detection bar  704  and the waste toner full detection member  711  stop rotating before the crank portion  741  reaches the bottom dead point. 
     Then, the driving gear  714  further rotates, and the rotation transmission rib  752  ( FIG. 10B ) of the driving gear  714  again contacts the rotation transmission rib  732  of the waste toner full detection member  711 . Therefore, the waste toner full detection bar  704  and the waste toner full detection member  711  start rotating at the constant speed. 
     In this case, the light reflecting portion  730  of the waste toner full detection member  711  passes the opening  734  of the detection member cover  712  at a constant speed. Therefore, a duration time of “ON” signal outputted by the detection sensor  760  (i.e., a time interval during which the detection sensor  760  receives reflection light) becomes shorter than in the case where the waste toner is not accumulated to the disposition area of the crank portion  741  ( FIG. 14 ). Further, a starting timing of the “ON” signal is delayed as compared with the case where the waste toner is not accumulated to the disposition area of the crank portion  741  ( FIG. 14 ). 
       FIG. 16A  is a timing chart showing an output (ON/OFF) of the detection sensor  760  in the case where the waste toner is not accumulated to the disposition area of the crank portion  741 .  FIG. 16B  is a timing chart showing the output of the detection sensor  760  in the case where the waste toner is accumulated to the disposition area of the crank portion  741 . 
     In the case where the waste toner is not accumulated to the disposition area of the crank portion  741 , after the crank portion  741  passes the top dead point ( FIG. 13 ), the waste toner full detection bar  704  and the waste toner full detection member  711  rotate by gravity due to the weight of the crank portion  741 . The crank portion  741  reaches the bottom dead point in a short time, and the light reflecting portion  730  of the waste toner full detection member  711  reaches a position facing the opening  734 , and the detection sensor  760  outputs “ON” signal as shown in  FIG. 16A . 
     Thereafter, as the driving gear  714  further rotates at the constant speed, the rotation transmission rib  752  ( FIG. 10B ) again contacts the rotation transmission rib  732  of the waste toner full detection member  711 , so that the waste toner full detection bar  704  and the waste toner full detection member  711  start rotating at the constant speed. The light reflecting portion  730  of the waste toner full detection member  711  leaves the position facing the opening  734 , and the detection sensor  760  outputs “OFF” signal. These motions are repeated in the case where the accumulated waste toner does not reach the disposition area of the crank portion  741 . 
     In contrast, in the case where the waste toner is accumulated to the disposition area of the crank portion  741 , after the crank portion  741  passes the top dead point ( FIG. 13 ), the waste toner full detection bar  704  and the waste toner full detection member  711  start rotating by gravity due to the weight of the crank portion  741 . However, the waste toner full detection bar  704  and the waste toner full detection member  711  stop rotating since the crank portion  741  contacts the accumulated waste toner. 
     Thereafter, as the driving gear  714  further rotates at the constant speed, the rotation transmission rib  752  ( FIG. 10B ) again contacts the rotation transmission rib  732  of the waste toner full detection member  711 , so that the waste toner full detection bar  704  and the waste toner full detection member  711  start rotating at the constant speed. The light reflecting portion  730  of the waste toner full detection member  711  reaches the position facing the opening  734 , and the detection sensor  760  outputs “ON” signal as shown in  FIG. 16B . 
     Therefore, the starting timing at which the detection sensor  760  outputs “ON” signal is delayed as compared with the case where the waste toner is not accumulated to the disposition area of the crank portion  741 . That is, there is a difference “d” in starting timing of “ON” signal between two cases shown in  FIGS. 16A and 16B . Further, there is the same difference “d” in the duration time of “ON” signal between two cases shown in  FIGS. 16A and 16B . 
     Accordingly, it becomes possible to detect that the waste toner (having been conveyed in the direction shown by the arrow I in the waste toner storage portion  40 ) is accumulated to the disposition area of the crank portion  741  based on the starting timing or the duration time of “ON” signal of the detection sensor  760 . In other words, a waste toner full state of the waste toner storage portion  40  can be detected based on the starting timing or the duration time of “ON” signal of the detection sensor  760 . 
     After the waste toner full state is detected as described above, the waste toner is further accumulated in the detection area γ of the waste toner storage portion  40  (where the crank portion  741  is provided) before the waste toner collecting container  32  is replaced by a user. 
     As described above, according to the first embodiment of the present invention, the waste toner conveying spiral  703  coveys the waste toner from the first end portion of the waste toner storage container  32  (where the waste toner receiving opening  720  is disposed) toward the second end portion of the waste toner storage container  32  opposite to the first end portion. Further, the crank portion  741  is located closer to the second end portion than to the first end portion. With such a configuration, the accumulation of the waste toner gradually proceeds in a direction from the first end portion toward the second end portion. Therefore, at a stage where the accumulated waste toner reaches the disposing area of the crank portion  741  (located closer to the second end portion than to the first end portion), the waste toner storage container  32  is almost filled with the waste toner. 
     Accordingly, a sufficient amount of the waste toner can be stored in the waste toner collecting container  32 . That is, a capacity of the waste toner storage portion  40  can be effectively used. Moreover, the accumulation of the waste toner is detected before the waste toner collecting container  32  is completely filled with the waste toner, and therefore leakage of the waste toner can be prevented. 
     Moreover, the waste toner storage container  32  includes the pushing area α in which the waste toner is conveyed by the first spiral portion  803 , and the detection area γ in which the waste toner is detected by the crank portion  741 . The accumulation area β in which the waste toner is accumulated provided between the pushing area α and the detection area γ. With such a configuration, the waste toner can be effectively stored in the waste toner collecting container  32  before the waste toner full state is detected. 
     In addition, it becomes possible to arbitrarily adjust a time interval after the accumulation of the waste toner is detected and before the waste toner collecting container  32  is completely filled with the waste toner, by adjusting the waste toner full detecting position C (i.e., the length of the crank portion  741 ). 
     Further, the first (upstream) spiral portion  803  of the waste toner conveying spiral  703  pushes the waste toner with a larger force, while the second (downstream) spiral portion  804  of the waste toner conveying spiral  703  pushes the waste toner with a smaller force. To be more specific, the second spiral portion  804  has almost no conveying capacity. Therefore, the waste toner conveying spiral  703  is only subjected to a load required for the first spiral portion  803  to push the waste toner. Further, the waste toner is not agglomerated by being pressed against the wall surface of the side plate  702  until the accumulated waste toner reaches the wall surface of the side plate  702 . Accordingly, an increase in load (torque) on the waste toner conveying spiral  703  can be suppressed. 
     Furthermore, the length of the crank portion  741  is shorter than or equal to a half (½) of the second spiral portion  804  of the waste toner conveying spiral  703 , and therefore the capacity of the waste toner storage portion  40  can be used at a maximum. The reason is described below. In order to use the capacity of the waste toner storage portion  40  at a maximum, it is necessary to calculate the accumulation state of the waste toner (i.e., whether the waste toner storage portion  40  is filled with the waste toner) after the waste toner full state is detected, but a calculation value may have a variation. According to the first embodiment of the present invention, since a large amount of the waste toner is stored in the waste toner storage portion  40  at timing when the waste toner full state is detected, it becomes possible to use the capacity of the waste toner storage portion  40  at a maximum even in consideration of the variation. 
     Moreover, the waste toner full detection bar  704  having the crank portion  741  constitutes the developer detecting portion. The rotation of the waste toner full detection bar  704  is optically detected. Therefore, the accumulation state of the waste toner is accurately detected based on the change in the rotational state of the waste toner full detection bar  704 . 
     In addition, the waste toner full detection bar  704  is provided above the waste toner conveying spiral  703 , and therefore the accumulation state of the waste toner can be detected with a simple configuration. In this regard, the waste toner full detection bar  704  is not necessarily provided directly above the waste toner conveying spiral  703 . It is only necessary that the waste toner full detection bar  704  is provided at a higher position than the waste toner conveying spiral  703 . 
     Second Embodiment 
     Next, the second embodiment of the present invention will be described.  FIG. 17  is a partially cut-away perspective view showing a waste toner collecting container  82  according to the second embodiment.  FIG. 18  is an enlarged view showing the vicinity of a waste toner receiving opening  720  of the waste toner collecting container  82 .  FIG. 19  is an enlarged view showing the vicinity of a driving portion of a waste toner full detection bar  704  of the waste toner collecting container  82 .  FIG. 20  is a sectional view showing an internal configuration of the waste toner collecting container  82 . In these figures, components that are the same as those of the first embodiment are assigned the same reference numerals. 
     The waste toner collecting container  82  of the second embodiment is different from the waste toner collecting container  32  of the first embodiment in configuration of the waste toner conveying spiral  805 . Further, an electrophotographic printer (hereinafter referred to as a printer) of the second embodiment is configured in a similar manner to the printer  1  of the first embodiment except for the waste toner collecting container  82 . 
     The waste toner conveying spiral  805  of the second embodiment has a non-spiral portion  806  instead of the second spiral portion  804  ( FIG. 5 ) of the waste toner conveying spiral  703  of the first embodiment. The non-spiral portion  806  has no spiral blade. That is, the waste toner conveying spiral  805  of the second embodiment has a first spiral portion  803  (i.e., a first portion) and a non-spiral portion  806  (i.e., a second portion) having no spiral portion. 
     The first spiral portion  803  extends from the vicinity of the end portion of the waste toner conveying spiral  805  on the conveyance starting side (i.e., the end portion where the waste toner receiving opening  720  is disposed) to a terminating position A. The terminating position A is shifted inwardly into the waste toner storage portion  40  with respect to the exit position B of the cylindrical conveying path  722 . The terminating position A is distanced from the exit position B by a distance L 1 . In a particular example, the distance L 1  is set in a range from 10 mm to 20 mm, which corresponds to one pitch or two pitches of the spiral blade of the first spiral portion  803 . 
     The first spiral portion  803  has the spiral blade having the height described in the first embodiment. The non-spiral portion  806  has no spiral blade, and does not contribute to conveyance of the waste toner. Since the non-spiral portion  806  does not contribute to conveyance of the waste toner, it becomes possible to eliminate a load on the non-spiral portion  806  due to resistance from the waste toner. Other configurations of the second embodiment are the same as those of the first embodiment. 
       FIG. 21  is a sectional view showing a manner in which the waste toner is conveyed and accumulated in the waste toner collecting container  82  according to the second embodiment. The waste toner collected into the waste toner collecting container  82  is conveyed by the first spiral portion  803  of the waste toner conveying spiral  805  along the cylindrical conveying path  722  in the direction shown by the arrow G. The waste toner is ejected from the cylindrical conveying path  722  via the toner exit  722   a , and is accumulated at the exit position B in a mound shape. The waste toner is accumulated at a height lower than the first spiral portion  803 . The accumulation of the waste toner proceeds in the direction shown by the arrow H. 
     When the accumulated waste toner reaches the terminating position A of the first spiral portion  803  of the waste toner conveying spiral  805 , the waste toner is accumulated in a mound shape beyond the height of the first spiral portion  803 . The accumulation of the waste toner proceeds in the direction shown by the arrow I. 
     As the amount of the waste toner in the waste toner storage portion  40  increases, the straight portion  742  of the rotating waste toner full detection bar  704  is buried in the waste toner. Further, when the accumulated waste toner reaches the waste toner full detecting position C, the crank portion  741  is subjected to rotational resistance, which causes a change in a rotational state of the waste toner full detection bar  704 . The change in the rotational state of the waste toner full detection bar  704  is detected as described in the first embodiment. 
     As described above, according to the second embodiment, the waste toner conveying spiral  805  includes the non-spiral portion  806  at a downstream part thereof in the conveying direction of the waste toner. Therefore, the non-spiral portion  806  is not subjected to resistance from the waste toner, and an increase in load (torque) on the waste toner conveying spiral  805  can be suppressed. 
     Third Embodiment 
     Next, the third embodiment of the present invention will be described.  FIG. 22  is an enlarged view showing the vicinity of a driving portion of a waste toner full detection bar  704  of a waste toner collecting container  132  according to the third embodiment.  FIG. 23  is a sectional view showing an internal configuration of the waste toner collecting container  132  according to the third embodiment. In these figures, components that are the same as those of the first embodiment are assigned the same reference numerals. 
     As shown in  FIGS. 22 and 23 , the waste toner collecting container  132  according to the third embodiment includes a waste toner full detection wall  901  as a movable body or a movable member. The waste toner full detection wall  901  is located on the straight portion  742  of the waste toner full detection bar  704 . The waste toner full detection wall  901  is provided so that the straight portion  742  of the waste toner full detection bar  704  penetrates the waste toner full detection wall  901 . Further, the waste toner full detection wall  901  is located upstream of the crank portion  741  in the conveying direction of the waste toner. 
     A resilient member  902  is provided on a side surface  901   d  of the waste toner detection wall  901  on the crank portion  741  side. The resilient member  902  is formed of, for example, a sponge. A movement regulating film  903  (i.e., a resilient film member of a movement regulating member) is provided between the waste toner full detection wall  901  and an upper inner surface (i.e., a ceiling) of the waste toner collecting container  132 . The movement regulating film  903  is configured to regulate a movement of the waste toner full detection wall  901  toward the crank portion  741  along the straight portion  742  of the waste toner full detection bar  704 . 
     The outer frame  701  of the waste toner collecting container  132  includes a first inner wall  701   a  and a second inner wall  701   b . Of the first inner wall  701   a  and the second inner wall  701   b , only the first inner wall  701   a  is shown in  FIGS. 22 and 23 . The first inner wall  701   a  and the second inner wall  701   b  face each other in a widthwise direction of the outer frame  701  (i.e., in a direction perpendicular to the longitudinal direction). A pair of guide ribs  701   c  are provided on the first inner wall  701   a  and the second inner wall  701   b . The guide ribs  701   c  are located at approximately the same height as the rotation axis  704   a  of the waste toner full detection bar  704 . The guide ribs  701   c  are parallel to the rotation axis  704   a . The guide ribs  701   c  are configured to support the waste toner full detection wall  901  so that the waste toner full detection wall  901  is slidable (movable). 
     In  FIG. 23 , the guide ribs  701   c  have rib widths that become wider than guide grooves  901   b  and  901   c  (described later) at an area located upstream of a predetermined position J along the waste toner full detection bar  704  in the conveying direction of the waste toner. In other words, the guide ribs  701   c  are configured to prevent the waste toner full detection wall  901  from moving upstream in the conveying direction of the waste toner beyond the position J. 
     The waste toner full detection wall  901  is formed of a resin. Further, the waste toner full detection wall  901  has an approximately square shape and has a thickness of approximately 1 mm. A through-hole  901   a  is formed on a center portion of the waste toner full detection wall  901 . An inner diameter of the through-hole  901   a  is so set that the straight portion  742  of the waste toner full detection bar  704  penetrates the through-hole  901   a  without contacting an inner periphery of the through-hole  901   a.    
     As shown in  FIG. 22 , the waste toner full detection wall  901  has a pair of guide grooves  901   b  and  901   c  that slidably engage the guide ribs  701   c . The guide grooves  901   b  and  901   c  have groove widths which are slightly wider than the rib widths of the guide ribs  701   c . Due to slidable engagement between the guide grooves  901   b  and  901   c  and the guide ribs  701   c , the waste toner full detection wall  901  moves (slides) along the guide ribs  701   c.    
     The resilient member  902  (for example, a sponge) has a through-hole  902   a  having substantially the same inner diameter as the through-hole  901   a  of the waste toner full detection wall  901 . The resilient member  902  is bonded to the side surface  901   d  of the waste toner full detection wall  901  facing the crank portion  741 . The through-hole  902   a  of the resilient member  902  is coaxial with the through-hole  901   a  of the waste toner full detection wall  901 . 
     A top end portion of the movement regulation film  903  is fixed to the inner wall  701   d  of the outer frame  701 . A lower end portion (i.e., a free end portion) of the movement regulating film  903  reaches to an upper end portion of the waste toner full detection wall  901  by a certain amount. With such a configuration, the movement regulating film  903  resiliently acts on the waste toner full detection wall  901  to prevent the waste toner full detection wall  901  from moving downstream (i.e., toward the crank portion  741 ) beyond the position J ( FIG. 23 ) in the conveying direction of the waste toner. 
     In this regard, in an upper region of the waste toner storage portion  40  above the waste toner full detection wall  901 , an area located upstream of the waste toner full detection wall  901  and an area located downstream of the waste toner full detection wall  901  are connected with each other. Further, in a region of the waste toner storage portion  40  below the waste toner full detection wall  901 , an area located upstream of the waste toner full detection wall  901  and an area located downstream of the waste toner full detection wall  901  are connected with each other. In other words, connecting portions are formed above and below the waste toner full detection wall  901 . 
     Other configurations of the waste toner collecting container  132  are the same as those of the waste toner collecting container  32  of the first embodiment. 
     Next, an operation of the waste toner collecting container  132  of the third embodiment will be described.  FIG. 24  is a sectional view showing a manner in which the waste toner is conveyed and accumulated in the waste toner collecting container  132  according to the third embodiment. 
     As described in the first embodiment, the waste toner is conveyed by the waste toner conveying spiral  703  in the direction shown by the arrow I, and is accumulated. When the accumulated waste toner reaches the above described position J, the waste toner full detection wall  901  is biased by the waste toner, and moves toward the crank portion  741  causing the movement regulation film  903  to be deflected. 
     Then, when the resilient member  902  contacts the crank portion  741  and starts to be pressed by the crank portion  741 , the crank portion  741  is subjected to frictional resistance from the resilient member  902 . This causes a change in a rotational state of the waste toner full detection bar  704  when rotating by gravity due to the weight of the crank portion  741 . 
     Since the waste toner full detection bar  704  rotates at the constant speed by the rotational force transmitted from the driving gear  714 , the output signal of the detection sensor  760  has a similar waveform as when the waste toner reaches the disposition area of the crank portion  741  in the first embodiment ( FIG. 16B ). Therefore, it becomes possible to detect that the waste toner (having being conveyed in the direction shown by the arrow I in the waste toner storage portion  40 ) to reach the crank portion  741 . In other words, the waste toner full state of the waste toner storage portion  40  can be detected. 
     Thereafter, the waste toner is further conveyed downstream (i.e., toward the crank portion  741 ) via the connecting portions above and below the waste toner full detection wall  901 . The waste toner is accumulated in a remaining part of the waste toner storage portion  40  until the waste toner collecting container  132  is replaced by a user. 
     As described above, according to the third embodiment of the present invention, the crank portion  741  is pressed by the waste toner full detection wall  901  and the resilient member  902 . This generates frictional resistance (i.e., a braking effect), and causes the change in the rotational state of the waste toner full detection bar  704  when rotating by gravity due to the weight of the crank portion  741 . The waste toner full state of the waste toner storage portion  40  can be detected based on the change in the rotational state of the waste toner full detection bar  704 . That is, the waste toner full state can be detected without being influenced by variation in accumulation state of the waste toner or variation in rotational resistance due to fluidity of the waste toner. As a result, detection accuracy of the waste toner full state can be enhanced. 
     Particularly, with a configuration in which the resilient member  902  (for example, the sponge) presses the crank portion  741 , an increase in load on the waste toner full detection bar  704  can be reduced. Further, since the waste toner full detection wall  902  is slidably provided, it becomes possible to cause the change in the rotational state of the crank portion  741  (the waste toner full detection bar  704 ) according to the accumulation state of the waste toner. 
     Fourth Embodiment 
     Next, the fourth embodiment of the present invention will be described.  FIG. 25  is a perspective view showing a waste toner collecting container  182  and a toner cartridge  3   k  according to the fourth embodiment.  FIG. 26  is a partially cut-away perspective view showing the waste toner collecting container  182  according to the fourth embodiment. In these figures, components that are the same as those of the first embodiment are assigned the same reference numerals. 
     In the fourth embodiment, the waste toner full state is detected without using the waste toner full detection bar  704  described in the first through third embodiments. 
     As shown in  FIG. 25 , the waste toner collecting container  182  of the fourth embodiment is mounted to the black toner cartridge  3   k . As shown in  FIGS. 25 and 26 , the waste toner collecting container  182  has an outer frame  781  and a side plate  782  that form a waste toner storage portion  80  in which the waste toner is stored. 
     As described in the first embodiment, the waste toner receiving opening  720  is formed on an end portion of the outer frame  781  in the longitudinal direction. The waste toner receiving opening  720  receives the waste toner having been conveyed by the second conveying mechanism  28  ( FIG. 1 ). A waste toner conveying spiral  783  is provided in the waste toner collecting container  182 . The waste toner conveying spiral  783  (i.e., a developer conveying unit) is configured to convey the waste toner collected via the waste toner receiving opening  720  toward an opposite end of the waste toner conveying spiral  783 . 
     An end of the waste toner conveying spiral  783  is rotatably supported by a shaft receiving portion  782   e  provided on a wall portion  782   a  of the side plate  782 . In the fourth embodiment, the waste toner full detection bar  704  is not provided. For this reason, gears for transmitting the rotation of the waste toner conveying spiral  783  to the waste toner full detection bar  704  is not provided. Further, the waste toner full detection member  711  is not provided. In other respects, the waste toner conveying spiral  783  is configured in a similar manner to the waste toner conveying spiral  703  ( FIG. 5 ) of the first embodiment or the waste toner conveying spiral  805  ( FIG. 17 ) of the second embodiment. 
     The side plate  782  of the waste toner collecting container  182  has the wall portion  782   a  on the conveyance termination side of the waste toner storage portion  80 . A protruding portion  782   b  is formed on the wall portion  782 , and protrudes outward the waste toner collecting container  182 . The protruding portion  782   b  includes a pair of wall portions  782   c  and  782   d  on both sides of the waste toner collecting container  182  in the widthwise direction. Light transmissive windows  800  and  801  (i.e., detection windows) are provided on the wall portions  782   c  and  782   d  so that the light transmissive windows  800  and  801  face each other. The light transmissive windows  800  and  801  are made of transparent plates. A light emitting portion  808  and a light receiving portion  809  ( FIG. 26 ) are disposed inside the printer  1  so that the light emitting portion  808  and the light receiving portion  809  respectively face the light transmissive windows  800  and  801 . The light emitting portion  808  and the light receiving portion  809  constitute a light-transmissive sensor. 
       FIG. 27  is a sectional view showing a manner in which the waste toner is conveyed and accumulated in the waste toner collecting container  182  according to the fourth embodiment. The waste toner is conveyed in the direction shown by the arrow I by the waste toner conveying spiral  783 , and is accumulated in the waste toner storage portion  80  as described in the first embodiment. 
     In the fourth embodiment, when the accumulated waste toner reaches the side plate  782  of the waste toner storage container  182 , an area between the light transmissive windows  800  and  801  is filled with the waste toner. Therefore, the waste toner blocks a light path between the light emitting portion  808  and the light receiving portion  809  of the light-transmissive sensor ( FIG. 26 ), with the result that an amount of light received by the light receiving portion  809  decreases. Therefore, it becomes possible to detect that the accumulated waste toner reaches the side plate  782  of the waste toner collecting container  182  by monitoring the amount of light received by the light receiving portion  809 . 
     As described above, according to the fourth embodiment of the present invention, the accumulation state of the waste toner can be detected based on a change in light transmissive state. Therefore, it is unnecessary to provide the waste toner full detection bar  704  described in the first through third embodiments. Accordingly, components required for detecting the waste tone can be reduced, and a manufacturing cost can be reduced. 
     Next, a modification of the fourth embodiment will be described.  FIG. 28  is a partially cut-away view showing the waste toner collecting container  182  according to a modification of the fourth embodiment. The waste toner conveying spiral  783  of the modification has the first spiral portion  803 , but does not have a portion downstream of the first spiral portion  803  in the conveying direction of the waste toner. Even with such a configuration, the waste toner conveying spiral  783  has function to convey the waste toner downstream (i.e., toward the side plate  782 ), and therefore the same advantages as the fourth embodiment can be obtained. 
     In the above described embodiments, the waste toner collecting containers storing the waste toner have been described. However, the present invention is also applicable to a developer storage body storing a developer (for example, a fresh toner) other than the waste toner. 
     Further, although the electrophotographic printer has been described as an example of the image forming apparatus, the present invention is also applicable to, for example, a copier, a facsimile machine, a multifunction peripheral or the like. 
     While the preferred embodiments of the present invention have been illustrated in detail, it should be apparent that modifications and improvements may be made to the invention without departing from the spirit and scope of the invention as described in the following claims.