Abstract:
A developer recovery device is provided with a recovery container that receives and accommodates a developer recovered from an image carrier, an agitator member that agitates the developer inside the recovery container, two shafts to which mutually engageable cams are respectively provided and that transmit rotational force to the agitator member, a spring that biases and causes to move one of the cams such that the two cams mutually engage and that causes a shaft connection between the two shafts to be joined, a torque limiter that carries out joining of the shaft connection, in which the two cams are caused to mutually engage to join the shaft connection, and disjoining of the shaft connection, in which the two cams are caused to move apart to disjoin the shaft connection, and a full-state determination portion that detects a disjoined state of the shaft connection and, based on the detected disjoined state, determines that the recovery container has become full of developer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119(a) on Patent Applications No. 2010-144908 and No. 2010-144909, filed in Japan on Jun. 25, 2010, the entire contents of which are herein incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to developer recovery devices, which recover and accommodate developer that is residual on an image carrier, and to image forming apparatuses including the same. 
         [0003]    Electrophotographic apparatuses are an example of this type of image forming apparatus. In image forming apparatuses of this type, an electrostatic latent image is formed on an image carrier, then the electrostatic latent image on the image carrier is developed using toner to form a toner image on the image carrier, the toner image is transferred from the image carrier to a recording paper, then the recording paper is subjected to heat and pressure to fix the toner image onto the recording paper. 
         [0004]    Picture quality is reduced in this image forming apparatus if residual toner on the image carrier is left as it is, and therefore the apparatus may have a configuration in which residual toner on the image carrier is removed and recovered in a recovery container. Furthermore, it is configured such that when the recovery container becomes full of toner, this is detected and reported so as to advise replacement of the recovery container. 
         [0005]    For example, in the developer recovery devices described in JP 2006-235382A (hereinafter referred to as Patent Document 1) and JP H8-129329A (hereinafter referred to as Patent Document 2), residual toner on a photosensitive drum or transfer belt is removed, and the removed toner is transported to a recovery container by a transport screw such that the removed toner is recovered in the recovery container. 
         [0006]    An agitator member is provided in the recovery container and the toner is agitated by the agitator member. Furthermore, a torque limiter is provided at a shaft that transmits rotational force to the agitator member in the developer recovery device. In this developer recovery device, when the recovery container becomes full of toner and an overload is exerted on the agitator member such that the agitator member becomes unable to rotate, the torque limiter becomes disjoined. When the torque limiter becomes disjoined, this is detected and a full state (recovery container full state) is determined indicating that the recovery container has become full of toner. 
         [0007]    In this regard, in Patent Documents 1 and 2, cams are provided in the torque limiter, and these cams engage with each other and are arranged on two shafts that transmit rotational force to the agitator member, and when an overload is exerted on the agitator member and the agitator member stops such that the rotation of one of the shafts stops, the cams slip and the shaft connection is disjoined. With this technique, the disjoining of the shaft connection is detected, thereby determining that the recovery container is in a full state. 
         [0008]    With a torque limiter such as this, sometimes the engagement state between the cams becomes unstable when the load on the agitator member increases close to an overload, and the disjoined state of the shaft connection also becomes unstable. Furthermore, in Patent Document 1, the recovery container is determined to be in a full state immediately upon detection of disjoining of the shaft connection, and therefore sometimes this determination is made even though the recovery container is not sufficiently full, which is a false determination. 
         [0009]    Accordingly, the present invention has been devised in consideration of the conventional problems described above, and it is an object thereof to provide a developer recovery device that is capable of accurately determining whether or not the recovery container is full of toner, and an image forming apparatus including the same. 
       SUMMARY OF THE INVENTION 
       [0010]    In order to address these issues, a developer recovery device according to the present invention is provided with a recovery container that receives and accommodates a developer recovered from an image carrier, an agitator member that agitates the developer inside the recovery container, two shafts to which mutually engageable cams are respectively provided and that transmit rotational force to the agitator member, a spring that biases and causes to move one of the cams such that the two cams mutually engage and that causes a shaft connection between the two shafts to be joined, a torque limiter that carries out joining of the shaft connection, in which the two cams are caused to mutually engage to join the shaft connection, and disjoining of the shaft connection, in which the two cams are caused to move apart to disjoin the shaft connection, and a full-state determination portion that detects a disjoined state of the shaft connection and, based on the detected disjoined state, determines that the recovery container has become full of developer, wherein the torque limiter is constituted by the two cams and the spring, and in a disjoined state of the shaft connection, due to the torque limiter, the one cam is stopped and the other cam rotates such that the two cams repetitively engage and move apart, and the full-state determination portion is provided with a switch that turns on/off in response to the engaging and moving apart of the two cams and obtains an on-off period of the switch, and in a case where the on-off period is within a prescribed time range that is set in advance and has been repeated at least a prescribed number of times that is set in advance, determines that the recovery container has become full of developer. 
         [0011]    With the present invention, the two cams mutually engage due to the spring, thereby causing a shaft connection of the two shafts to join. Thus, as long as the recovery container does not become full of developer and an overload is not exerted on the agitator member, the two cams engage to form a shaft connection, and rotational force is transmitted to the agitator member via the shafts such that the agitator member rotates. Furthermore, when the recovery container becomes full of developer and an overload is exerted on the agitator member such that the agitator member does not rotate and one of the shafts stops, the cams slip and the shaft connection is disjoined. 
         [0012]    And, in a disjoined state of the shaft connection, while one of the cams stops and the other cam rotates, the two cams repetitively engage and move apart. Accordingly, the full-state determination portion obtains the on-off period of the switch that turns on/off in response to the engaging and moving apart of the two cams, and in a case where the on-off period is within a prescribed time range and has been repeated at least a prescribed times, determines that the recovery container has become full of developer. In this way, it can be accurately determined that the recovery container is full. 
         [0013]    For example, when the load on the agitator member increases close to an overload such that the engagement state of the two cams of the torque limiter becomes unstable, the engaging and moving apart of the two cams repeats irregularly such that on-off period of the switch fluctuates wildly and departs from the prescribed time range, or the on-off periods within the prescribed time range are not repeated more than the prescribed number of times, and therefore it cannot be determined that the recovery container is in a full state. Furthermore, in a case where the switch or the like malfunctions, the on-off of the switch does not repeat and it cannot be determined that the recovery container is in a full state. 
         [0014]    Furthermore, a developer recovery device according to the present invention is provided with a recovery container that receives and accommodates a developer recovered from an image carrier, an agitator member that agitates the developer inside the recovery container, two shafts to which mutually engageable cams are respectively provided and that transmit rotational force to the agitator member, a spring that biases and causes to move one of the cams such that the two cams mutually engage and that causes a shaft connection between the two shafts to be joined, a torque limiter that carries out joining of the shaft connection, in which the two cams are caused to mutually engage to join the shaft connection, and disjoining of the shaft connection, in which the two cams are caused to move apart to disjoin the shaft connection, and a full-state determination portion that detects a disjoined state of the shaft connection and, based on the detected disjoined state, determines that the recovery container has become full of developer, wherein the torque limiter is constituted by the two cams and the spring, and in a disjoined state of the shaft connection, due to the torque limiter, the one cam is stopped rotating and the other cam rotates such that the two cams repetitively engage and move apart, and the full-state determination portion is provided with a switch that turns on/off in response to the engaging and moving apart of the cams, obtains an on time of the switch and an off time of the switch, and in a case where the on time is within a first prescribed time range that is set in advance and the off time is within a second prescribed time range that is set in advance, determines that the recovery container has become full of developer. 
         [0015]    In this way, the full-state determination portion obtains the on time and the off time of the switch that turns on/off in response to the engaging and moving apart of the two cams, and in a case where the on time is within the first prescribed time range and the off time is within the second prescribed time range, determines that the recovery container has become full of developer. In this way, it can be accurately determined that the recovery container is full. 
         [0016]    For example, when the load on the agitator member increases close to an overload such that the engagement state of the two cams of the torque limiter becomes unstable, the engaging and moving apart of the two cams repeats irregularly such that the on time or the off time of the switch is too short or too long, and the on time departs from the first prescribed time range and the off time departs from the second prescribed time range, and therefore no determination is made that the recovery container is in a full state. Furthermore, also in a case where the switch or the like malfunctions, the on time or the off time of the switch becomes long and the on time or the off time departs from the first prescribed time range or the second prescribed time range, and therefore it cannot be determined that the recovery container is in a full state. 
         [0017]    In this regard, in Patent Document 2, rotation of one of the shafts is detected by a sensor and a pulse signal outputted from the sensor in accordance with rotation of the one shaft is monitored, and the output number of the pulse signal per unit of time gradually decreases and when the pulse signal completely stops being outputted, it is determined that the recovery container is in a full state, and therefore sometimes false determinations naturally occurred. For example, the recovery container was determined to be in a full state when the pulse signal from the sensor stopped being outputted due to a malfunction or the like such that sometimes false determinations occurred. 
         [0018]    In contrast to this, as described above, the present invention can also address this conventional problem as well, and is capable of accurately determining whether or not the recovery container is full of toner. 
         [0019]    Furthermore, in the developer recovery device according to the present invention, the full-state determination portion, in rotationally driving the agitator member, when the switch changes to on or off and the on/off state after the change continues for at least a malfunction determination time that is set in advance, may determine that a malfunction has occurred. 
         [0020]    In this case, if the recovery container is not full of developer, the two cams engage such that the shaft connection is joined and the agitator member continues to rotate, and therefore the switch does not change. Furthermore, when the recovery container becomes full of developer such that an overload is exerted on the agitator member and the agitator member stops rotating, the cams slip and while one cam stops the other cam rotates such that the two cams repetitively engage and move apart so that the on/off of the switch also repeats, and therefore there is no long continuation of either the on or off state. Accordingly, in rotationally driving the agitator member, when the switch changes to on or off and the on/off state after the change has continued for at least the malfunction determination time, it can be determined that a malfunction has occurred. 
         [0021]    Further still, in the developer recovery device according to the present invention, the torque limiter may be constituted by a second rotation member that is integrally secured to the one cam and that rotates and moves together with the one cam, and the switch may turn on/off by detecting a position of the second rotation member. 
         [0022]    Furthermore, in the developer recovery device according to the present invention, the second rotation member may be a gear and the gear may mesh with a gear provided on a shaft of the agitator member. 
         [0023]    In this case, the second rotation member not only pushes against one end of the spring but also fulfills a function as a gear that transmits rotational force. 
         [0024]    In this regard, in the conventional techniques described in Patent Documents 1 and 2, one end of the spring abuts against a frame or a wall surface. In this case, the one end of the spring strongly abuts against the frame or the wall surface due to the biasing force of the spring and it is difficult for it to rotate. In this state, when one of the shafts rotates, the spring becomes twisted and due to this twisting the biasing force of the spring fluctuates such that the overload of the agitator member also fluctuates when the shaft connection is disjoined. For this reason, the determination that the recovery container is in a full state becomes inaccurate and the replacements of the recovery container cannot be carried out properly. 
         [0025]    For example, when the biasing force of the spring decreases, the shaft connection disjoins even though the recovery container is not in a full state and prior to the exertion of an overload to the agitator member, such that a determination is made that the recovery container is in a full state. 
         [0026]    Furthermore, in a case where the frame or the wall surface has been formed by a synthetic resin or the like, the one end of the spring rotates while strongly abutting against the frame or the wall surface, thereby causing wear to the frame or the wall surface or producing noise. 
         [0027]    It should be noted in regard to Patent Document 1 that although no abutment location can be specified for the one end of the spring from the specification and drawings, since it is necessary for the spring to be compressed, it is conceivable that the one end of the spring presses against a secured surface (a frame or a wall surface). 
         [0028]    Accordingly, to also address these conventional problems as well, another developer recovery device according to the present invention is provided with a recovery container that receives and accommodates a developer recovered from an image carrier, an agitator member that agitates the developer inside the recovery container, two shafts to which mutually engageable cams are respectively provided and that transmit rotational force to the agitator member, a first rotation member that is integrally secured to the one cam and that rotates together with the one cam, a second rotation member that is positioned along a shaft of the first rotation member, which is provided with the one cam, and that rotates together with the one cam, a spring that is interposed between the first rotation member and the second rotation member, that biases and causes to move the one cam such that the two cams mutually engage, and that causes a shaft connection between the two shafts to be joined, a torque limiter that includes the two cams and the spring, and that carries out joining of the shaft connection, in which the two cams are caused to mutually engage to join the shaft connection, and disjoining of the shaft connection, in which the two cams are caused to move apart to disjoin the shaft connection, and a full-state determination portion that detects a disjoined state of the shaft connection and, based on the detected disjoined state, determines that the recovery container has become full of developer. 
         [0029]    With the present invention it is possible to accurately determine whether or not the recovery container is full of toner. 
         [0030]    Furthermore, with the present invention, a spring is squeezed between the first rotation member and the second rotation member such the first rotation member and the one cam are biased by the spring with respect to the second rotation member, and the two cams mutually engage so as to join a shaft connection of the two shafts. Thus, as long as the recovery container does not become full of developer and an overload is not exerted on the agitator member, the two cams engage to form a shaft connection, and rotational force is transmitted to the agitator member via the shafts such that the agitator member rotates. Furthermore, when the recovery container becomes full of developer and an overload is exerted on the agitator member such that the agitator member does not rotate, the cams slip resisting the biasing force of the spring and the shaft connection is disjoined. 
         [0031]    Since the first rotation member and the second rotation member rotate together with the one cam, both ends of the spring squeezed therebetween also rotate such that there is no twisting of the spring and the biasing force of the spring is stabilized. For this reason, the overload of the agitator member when the shaft connection is disjoined in resistance to the biasing force of the spring becomes stabilized, and the determination of a full state of the recovery container becomes accurate based on the disjoined state of the shaft connection, thereby enabling replacement of the recovery container with proper timings. 
         [0032]    Furthermore, no extra load is exerted on either the first rotation member or the second rotation member such that the durability of the device can be improved without causing wear to the first rotation member or the second rotation member. 
         [0033]    Furthermore, in the developer recovery device according to the present invention, the second rotation member may be a gear and may mesh with a gear secured on a shaft of the agitator member. 
         [0034]    In this case, the second rotation member not only pushes against one end of the spring but also fulfills a function as a gear that transmits rotational force. 
         [0035]    Further still, in the developer recovery device according to the present invention, when a position of the first rotation member is detected at a time when the cams have slipped resisting the biasing force of the spring and the shaft connection has become disjoined, the full-state determination portion may determine that the recovery container has become full of developer. 
         [0036]    When the recovery container has become full of developer, an overload is exerted on the agitator member and the cams slip resisting the biasing force of the spring, and the first rotation member moves together with the one cam. Thus, a position of the first rotation member is detected and based on the detected position, it is possible to determine that the recovery container has become full of developer. 
         [0037]    Furthermore, in the developer recovery device according to the present invention, a shaft of the first rotation member may be provided with a claw, and a rib is formed in the first rotation member, a hole may be provided and a groove may be formed in the second rotation member, the shaft of the first rotation member may be inserted into the hole of the second rotation member so as to be movable, the claw of the shaft of the first rotation member may catch onto a peripheral edge of the hole of the second rotation member, and the rib of the first rotation member may engage with the groove of the second rotation member such that the first rotation member and the second rotation member rotate together. In this case, the shaft of the first rotation member is inserted into a central hole of the second rotation member so as to be movable, and the claw of the shaft of the first rotation member catches onto a peripheral edge of the central hole of the second rotation member, thereby preventing the second rotation member from coming off from the shaft of the first rotation member, and the rib of the first rotation member engages with the groove of the second rotation member so that the first rotation member and the second rotation member rotate together. 
         [0038]    Further still, in the developer recovery device according to the present invention, the spring is a coil spring into which the shaft of the first rotation member is inserted. 
         [0039]    On the other hand, an image forming apparatus according to the present invention is provided with a developer recovery device according to the present invention described above. Equivalent effects are also achieved in an image forming apparatus according to the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]      FIG. 1  is a cross-sectional view showing an image forming apparatus in which is applied one embodiment of a developer recovery device according to the present invention. 
           [0041]      FIG. 2  is a perspective view showing a toner recover container and a rotational drive unit in the developer recovery device as viewed from the front side of the image forming apparatus. 
           [0042]      FIG. 3  is a vertical cross-sectional view of the toner recovery container in the developer recovery device as viewed from the front side of the image forming apparatus, and shows an internal structure of a rear area side. 
           [0043]      FIG. 4  is a cross-sectional view showing the toner recovery container and a toner recovery portion provided in each of the cleaning devices in the developer recovery device. 
           [0044]      FIG. 5  is a perspective view showing a rotational drive unit in the developer recovery device as viewed from the front side. 
           [0045]      FIG. 6  is a perspective view showing the rotational drive unit in the developer recovery device as viewed from the rear. 
           [0046]      FIG. 7  is a front view showing the rotational drive unit in the developer recovery device. 
           [0047]      FIG. 8  is constituted by  FIG. 8A  and  FIG. 8B .  FIG. 8A  is a cross-sectional view showing an enlargement of an output gear, a coupling gear, a coupling flange, and a coil spring in the rotational drive unit, and  FIG. 8B  is a top view showing the output gear and other components. 
           [0048]      FIG. 9  is a block diagram showing a configuration of a control system that determines a state of attachment/detachment or a full state of the toner recovery container, or a malfunction state of the developer recovery device. 
           [0049]      FIG. 10  is a front view showing the rotational drive unit when the toner recovery container is mounted. 
           [0050]      FIG. 11  is a front view of the rotational drive unit when the toner recovery container is mounted, and shows a disjoined state of the torque limiter. 
           [0051]      FIG. 12  is a timing chart showing on/off states of the switch when the toner recovery container in the rotational drive unit has become full of toner. 
           [0052]      FIG. 13  is a timing chart showing on/off states of the switch when a malfunction has occurred in the developer recovery device. 
       
    
    
     REFERENCE SIGNS LIST 
       [0000]    
       
           1  Image forming apparatus 
           2  Image reading device 
           11  Laser exposure device 
           12  Development device 
           13  Photosensitive drum 
           14  Drum cleaning device 
           15  Charger 
           16  Intermediate transfer belt device 
           17  Fixing device 
           18  Paper feed tray 
           19  Paper discharge tray 
           41  Reading scanner 
           42  Original transport device 
           77  Agitator blade 
           91  Movable lever portion 
           92  Output gear (second rotation member) 
           93  Input gear 
           94  Worm gear 
           95  Coupling gear 
           96  Coupling flange (first rotation member) 
           97  Coil spring 
           98  Switch 
           99  Knob 
           101  Frame 
           121  Control portion (full-state determination portion) 
           122  Display portion 
         UN Rotational drive unit 
       
     
       DESCRIPTION OF EMBODIMENTS 
       [0080]    Hereinafter, embodiments of the present invention are described in detail with reference to the accompanying drawings. 
         [0081]      FIG. 1  is a cross-sectional view showing an image forming apparatus in which is applied one embodiment of a developer recovery device according to the present invention. An image forming apparatus  1  is a so-called multifunction machine having functions such as a scanning function, a copying function, a printing function, and a fax machine function, and an image of an original that has been read by an image reading device  2  is transmitted externally (corresponding to the scanning function), then the image of this original that has been read by the image reading device  2 , or an image that has been received from outside is recorded and formed on a recording paper in color or monochrome (corresponding to the copying function, printing function, and fax machine function). It should be noted that in  FIG. 1 , a position of a developer recovery device  71  in the image forming apparatus  1  is shown by a dashed line. 
         [0082]    In order to print an image on a recording paper, the image forming apparatus  1  is provided with components such as a laser exposure device  11 , development devices  12 , photosensitive drums  13 , drum cleaning devices  14 , chargers  15 , an intermediate transfer belt device  16 , a fixing device  17 , a paper transport path S, a paper feed tray  18 , and a paper discharge tray  19 . 
         [0083]    The image data handled in the image forming apparatus  1  corresponds to color images using each of the colors black (K), cyan (C), magenta (M), and yellow (Y), or corresponds to a monochrome image using a single color (for example, black). Thus, four sets each of the development devices  12 , the photosensitive drums  13 , the drum cleaning devices  14 , and the chargers  15  are provided to form four toner images corresponding to the four colors, with these being associated with black, cyan, magenta, and yellow respectively, thereby constituting four image stations Pa, Pb, Pc, and Pd. 
         [0084]    Each of the photosensitive drums  3  in the image stations Pa, Pb, Pc, and Pd is provided with a photosensitive layer on its surface. Each of the chargers  15  is a charging means for uniformly charging the surface of its respective photosensitive drum  13  to a predetermined electric potential and in addition to contact types such as roller and brush charging units, charger-type chargers are also used. 
         [0085]    The laser exposure device  11  is a laser scanning unit (LSU) provided with a laser diode and reflective mirrors, and this exposes the surface of each of the charged photosensitive drums  13  in response to image data such that an electrostatic latent image is formed on each of the surfaces corresponding to the image data. 
         [0086]    Each of the development devices  12  develops the electrostatic latent image formed on the surface of its respective photosensitive drum  13  using one of the color toners, thereby forming toner images on the surfaces of the photosensitive drums  13 . Each of the drum cleaning devices  14  removes and recovers toner that is residual on the surface of its respective photosensitive drum  13  after development and image transfer. 
         [0087]    The intermediate transfer belt device  16  is positioned above the photosensitive drums  13 , and is provided with an intermediate transfer belt  21 , an intermediate transfer belt drive roller  22 , an idler roller  23 , four intermediate transfer rollers  24 , and a belt cleaning device  25 . 
         [0088]    The intermediate transfer belt  21  is a film formed in an endless belt shape. The intermediate transfer belt  21  spans in a tensioned state and is supported by the intermediate transfer belt drive roller  22 , the idler roller  23 , and intermediate transfer rollers  24 . The intermediate transfer belt  21  is caused to move there-around in a direction of arrow C. 
         [0089]    Each of the intermediate transfer rollers  24  is rotatably supported near the intermediate transfer belt  21 , and presses against its respective photosensitive drum  13  through the intermediate transfer belt  21 . The toner image on the surface of each of the photosensitive drums  13  is superimposed and transferred in order onto the intermediate transfer belt  21 , thereby forming a color toner image (a toner image having each of these colors) on the intermediate transfer belt  21 . Transfer of the toner image from each of the photosensitive drums  13  to the intermediate transfer belt  21  is carried out by each of the intermediate transfer rollers  24  that press against the rear surface of the intermediate transfer belt  21 . Each of the intermediate transfer rollers  24  is a roller in which a metal shaft (for example stainless steel) is used as a core and the surface thereof is covered by a conductive elastic material (for example, EPDM or urethane foam or the like). A high voltage transfer bias (a high voltage that has opposite polarity (+) to the charge polarity (−) of the toner) is applied to each of the intermediate transfer rollers  24  to achieve transfer of the toner images, and the high voltage is applied uniformly to the recording paper due to the conductivity of the elastic material. 
         [0090]    Thus, the toner image on the surface of each of the photosensitive drums  13  is transferred and layered onto the intermediate transfer belt  21  to become a color toner image indicated by the image data. This color toner image is transported together with the intermediate transfer belt  21  then transferred onto a recording paper at a nip region between the intermediate transfer belt  21  and a transfer roller  26   a  of a secondary transfer device  26 . 
         [0091]    A voltage (a high voltage that has an opposite polarity (+) to the charge polarity (−) of the toner) is applied to the transfer roller  26   a  of the secondary transfer device  26  in order for the color toner image on the intermediate transfer belt  21  to be transferred to the recording paper. 
         [0092]    In this regard, sometimes the toner images on the intermediate transfer belt  21  are not completely transferred onto the recording paper by the secondary transfer device  26  such that some toner becomes residual on the surface of the intermediate transfer belt  21 , and this residual toner is a cause of toner colors becoming mixed undesirably at subsequent steps. In order to address this problem, the belt cleaning device  25  is provided in the image forming apparatus  1  and the residual toner on the surface of the intermediate transfer belt  21  is removed and recovered by the belt cleaning device  25 . In the belt cleaning device  25 , a cleaning blade is provided for example as a cleaning member that contacts the surface of the intermediate transfer belt  21  and removes residual toner, and the rear side of the intermediate transfer belt  21  is supported by the idler roller  23  at a position where the cleaning blade contacts the intermediate transfer belt  21 . 
         [0093]    After the color (or monochrome) toner image has been transferred at the nip region between the intermediate transfer belt  21  and the transfer roller  26   a  of the secondary transfer device  26 , the recording paper is transported to the fixing device  17 . The fixing device  17  is provided with components such as a heating roller  31  and a pressure roller  32 , and the recording paper is transported sandwiched between the heating roller  31  and the pressure roller. 
         [0094]    The heating roller  31  is controlled based on detection output from an unshown temperature detector so as to reach a predetermined fixing temperature, and melts, mixes, and presses the color toner image that has been transferred onto the recording paper to thermally fix it to the recording paper by applying thermocompression to the recording paper along with the pressure roller  32 . 
         [0095]    Furthermore, a paper feed tray  18  that supplies recording papers is provided at a lower portion of the image forming apparatus  1 . A paper transport path S is provided in the image forming apparatus  1  for sending the recording paper supplied from the paper feeding tray  18  to the paper discharge tray  19  via the secondary transfer device  26  and the fixing device  17 . 
         [0096]    A paper pickup roller  33  is provided at an end portion of the paper feed tray  18 , and recording papers are withdrawn sheet by sheet from the paper feed tray  18  by this paper pickup roller  33  to be transported to the paper transport path S. 
         [0097]    Arranged along the paper transport path S (which also includes a reverse path Sr) are components such as paper registration rollers  34 , the fixing device  17 , transport rollers  35 , and discharge rollers  36 . The transport rollers  35  are small-size rollers for facilitating and assisting the transport of the recording papers, and a plurality of pairs of these are provided. 
         [0098]    The paper registration rollers  34  provide well timed transport of the recording papers by temporarily stopping the recording paper that has been transported in and aligning the leading edge of the recording paper, then the rotations of each of the photosensitive drums  13  and the intermediate transfer belt  21  are matched so that the (color) toner image on the intermediate transfer belt  21  is transferred onto the recording paper at the nip region between the intermediate transfer belt  21  and the transfer roller  26   a  of the secondary transfer device  26 . 
         [0099]    It should be noted that the color toner image is fixed by the fixing device  17  onto the recording paper that is transported by the paper registration rollers  34  and passes through the fixing device  17 . Then, the recording paper on which the toner image has been fixed by the fixing device  17  is discharged face down on the paper discharge tray  19  by the discharge rollers  36 . 
         [0100]    Furthermore, in a case of carrying out printing not only on the front side of the recording paper but on the rear side as well, the discharge rollers  36  are caused to pause midway during transport of the recording paper by the discharge rollers  36  then to rotate in reverse such that the front and rear of the recording paper are inverted by passing through the reverse path Sr, then the recording paper is guided to the paper registration rollers  34  and, in a same manner as the front side of the recording paper, an image is recorded by a toner image being transferred to the rear side of the recording paper, after which the image is fixed to the recording paper then discharged to the paper discharge tray  19 . 
         [0101]    Next, description is given regarding the image reading device  2 , which is mounted on an upper portion of the main unit of the image forming apparatus  1 . The image reading device  2  is provided with a reading scanner  41  of a lower side and an original transport device  42  of an upper side. One inner side of the original transport device  42  of the upper side is pivotably supported by a hinge (not shown in drawings) on one inner side of the reading scanner  41  of the lower side, and a front area of the original transport device  42  can be opened and closed by being raised or lowered. When the original transport device  42  is open, a platen glass  44  of the reading scanner  41  is uncovered. An original is placed on this platen glass  44 . 
         [0102]    The reading scanner  41  is provided with components such as the platen glass  44 , a first scanning unit  45 , a second scanning unit  46 , an imaging lens  47 , and a CCD (charge coupled device)  48 . While the first scanning unit  45 , which is provided with an illumination device  51  and a first reflective mirror  52 , moves in a sub scanning direction Y at a constant velocity V for a distance corresponding to the size of the original, the original on the platen glass  44  is exposed to light by the illumination device  51 , and the reflected light thereof is reflected by the first reflective mirror  52  and guided to the second scanning unit  46 , and in this way an image of the surface of the original is scanned in the sub scanning direction. While the second scanning unit  46 , which is provided with second and third reflective mirrors  53  and  54 , moves at a velocity V/2 following the first scanning unit  45 , the reflected light from the original is reflected by the second and third reflective mirrors  53  and  54  and guided to the imaging lens  47 . The imaging lens  47  focuses the reflected light from the original onto the CCD  48  such that an image of the surface of the original is formed on the CCD  48 . The CCD  48  repetitively scans the image of the original in the main scanning direction and at each scan it outputs analog image signals of one main scanning line. 
         [0103]    Furthermore, the reading scanner  41  is also capable of reading not only stationary originals, but also capable of reading an image of the surface of an original that is being transported by the original transport device  42 . In this case, the first scanning unit  45  is caused to move in a reading range below an original reading glass  55 , and the second scanning unit  46  is positioned in response to the position of the first scanning unit  45 , then in this state, transport commences of the original by the original transport device  42 . 
         [0104]    In the original transport device  42 , a pickup roller  56  presses against an original at the top of an original tray  57  and rotates, thereby pulling the original into an original transport path  58 . Then, the original transported on the original transport path  58  passes between the original reading glass  55  and a reading guide panel  59 , then the original is further transported from a discharge roller  61  to a discharge tray  62 . It should be noted that in this original transport device  42 , registration rollers  63 , which align a leading edge of the original for transport, and transport rollers  64 , which transport the original, are arranged along the original transport path  58 . 
         [0105]    Furthermore, during the transport of this original, the surface of the original is illuminated through the original reading glass  55  by the illumination device  51  of the first scanning unit  45 , and reflected light from the surface of the original is guided to the imaging lens  47  by the reflective mirrors of the first and second scanning units  45  and  46 , then the reflected light from the surface of the original is focused on the CCD  48  by the imaging lens  47  such that an image of the surface of the original is formed on the CCD  48 , and in this way an image of the surface of the original is read. 
         [0106]    Furthermore, in a case of reading the rear surface of the original, an intermediate tray  67  rotates on its shaft as shown by the dotted line (see  FIG. 1 ), then midway while the original is being discharged by the discharge rollers  61  to the discharge tray  62 , the discharge rollers  61  are caused to stop, then the original is received on the intermediate tray  67  and the discharge rollers  61  are caused to rotate in reverse such that the original is guided to the registration rollers  63  via the reverse transport path  68 , thereby reversing the front and back of the original, then an image of the rear surface of the original is read in a same manner as the image of the front surface of the original, and the intermediate tray returns to its original position as shown by the solid line (see  FIG. 1 ), and the original is discharged from the discharge rollers  61  to the discharge tray  62 . 
         [0107]    The image of the original that has been read by the CCD  48  in this manner is outputted as analog image signals from the CCD  48 , and these analog image signals undergo A/D conversion to digital image signals (image data). Then, this image data is sent to the laser exposure device  11  of the image forming apparatus  1  after undergoing various types of image processing, and the image is recorded onto a recording paper using an image forming portion constituted by the laser exposure device  11  that has obtained (received) the image data, and the image stations Pa, Pb, Pc, and Pd, then the recording paper is outputted as a reproduced original. 
         [0108]    On the other hand, as described above, in the image forming apparatus  1 , the residual toner on the surface of each of the photosensitive drums  13  is removed by the respective drum cleaning device  14 , and the residual toner on the surface of the intermediate transfer belt  21  is removed by the belt cleaning device  25 . The toner that is removed by these cleaning devices  14  and  25  is transported to the developer recovery device  71  (see below) according to the present embodiment, then collected and accommodated in the developer recovery device  71 . 
         [0109]      FIG. 2  is a perspective view showing a toner recovery container  72  and a rotational drive unit UN (see below) in the developer recovery device  71  according to the present embodiment as viewed from the front side of the image forming apparatus  1 . Furthermore,  FIG. 3  is a vertical cross-sectional view of the toner recovery container  72  in the developer recovery device  71  as viewed from the front side of the image forming apparatus  1 , and shows an internal structure of a rear area side. Furthermore,  FIG. 4  is a cross-sectional view showing the toner recovery container  72  and a toner recovery portion  73  provided in each of the cleaning devices  14  and  25  in the developer recovery device  71 . 
         [0110]    As shown in  FIG. 1 , the developer recovery device  71  according to the present embodiment is arranged near the cleaning devices  14  and  25 , and as shown in  FIGS. 2 to 4 , is provided with the image forming toner recovery container  72 , toner recovery portions  73 , and the rotational drive unit UN. 
         [0111]    The toner recovery container  72  is arranged in a near side (front side) space inside in the image forming apparatus  1 , and is provided with an upper side container  72 - 1  and a lower side container  72 - 2 . The upper side container  72 - 1  is connected to the toner recovery portions  73  (see  FIG. 4 ) arranged on the side of the cleaning devices  14  and  25 , and toner that is transported in by each of the toner recovery portions  73  is introduced and received here. The lower side container  72 - 2  accommodates the toner that has been introduced to the upper side container  72 - 1 . 
         [0112]    The upper side container  72 - 1  is a housing having a near side wall portion  74 , a rear surface side wall portion  75 , and a bottom side opening portion  76 , and agitator blades  77  are arranged at the bottom side opening portion  76 . The lower side container  72 - 2  is a housing that mounts to the bottom side of the upper side container  72 - 1  and is provided with an upper side opening portion  78 . 
         [0113]    As shown in  FIG. 2 , multiple coupling holes  72   a  are formed at an outer circumferential lower side of the upper side container  72 - 1 , and multiple claws  72   c  are formed at an outer circumferential upper side of the lower side container  72 - 2 . In regard to the upper side container  72 - 1  and the lower side container  72 - 2 , the upper side opening portion  78  of the lower side container  72 - 2  fits into an inner side of the bottom side opening portion  76  of the upper side container  72 - 1 , and the claws  72   c  of the lower side container  72 - 2  engage into the coupling holes  72   a  of the upper side container  72 - 1  respectively such that the lower side container  72 - 2  mounts into the bottom side of the upper side container  72 - 1 . 
         [0114]    Furthermore, as shown in  FIGS. 2 and 3 , a hook  72   b  is formed at a rear surface upper side of the upper side container  72 - 1 , and protruding portions  72   d  and  72   e  are formed at bottom side ends of the lower side container  72 - 2 . The lower side container  72 - 2  is placed on a frame (not shown in drawings) of the image forming apparatus  1  such that, as shown in  FIG. 2 , the protruding portion  72   d  on the bottom side left end of the lower side container  72 - 2  fits into a recess  79   a  of an attachment member  79  of the image forming apparatus  1 , and the hook  72   b  of the rear surface upper side of the upper side container  72 - 1  engages with an engaging portion (not shown in drawings) of the frame of the image forming apparatus  1  such that the toner recovery container  72  mounts to the image forming apparatus  1 . 
         [0115]    As shown in  FIG. 2 , in a state in which the toner recovery container  72  is mounted, the protruding portion  72   e  of the bottom side right end of the lower side container  72 - 2  is placed on a lever  91   a  of the rotational drive unit UN, which is provided on the image forming apparatus  1  side, thereby pressing down on the lever  91   a.  Furthermore, as shown in  FIG. 4 , the toner recovery portions  73 , which are arranged on the side of each of the cleaning devices  14  and  25 , are connected at the rear surface of the upper side container  72 - 1 . 
         [0116]    Here, as shown in  FIGS. 3 and 4 , four tubular introduction portions  75   a,    75   b,    75   c,  and  75   d  and one tubular introduction portion  75   e  are formed at the rear surface side wall portion  75  of the upper side container  72 - 1 . Furthermore, the toner recovery portions  73  on the side of the cleaning devices  14  and  25  are provided with a transport screw  82 , and the transport screw  82  is arranged inside each of multiple conduit tubes  81 . To describe in further detail the relationships between the upper side container  72 - 1  and the toner recovery portions  73 , an end portion  81   a  of each of the conduit tubes  81  of the toner recovery portions  73  on the side of the cleaning devices  14  and  25  is inserted into the tubular introduction portions  75   a  to  75   e  of the rear surface side wall portion  75  of the upper side container  72 - 1  such that the toner recovery portions  73  on the side of the cleaning devices  14  and  25  are connected at the rear surface of the upper side container  72 - 1 . 
         [0117]    The four tubular introduction portions  75   a  to  75   d  correspond to the cleaning devices  14  that perform cleaning respectively on each of the photosensitive drums  13 , which form toner images in four colors, and the end portions  81   a  of the conduit tubes  81  of the toner recovery portions  73  on the side of each of the cleaning devices  14  is inserted into these tubular introduction portions  75   a  to  75   d.  The conduit tubes  81  of the toner recovery portions  73  are arranged along the lengthwise direction of the photosensitive drums  13  respectively, and are provided with open slits (not shown in drawings) along this lengthwise direction. The toner that is removed from the surface of the each of the photosensitive drums  13  by a blade or the like of the cleaning devices  14  is disposed respectively into the conduit tubes  81  via these open slits. Each of the transport screws  82  is rotationally driven in one direction inside its respective conduit tube  81 , and the toner inside each of these conduit tubes  81  is transported (drawn out) in the direction of the tubular introduction portions  75   a  to  75   d  of the upper side container  72 - 1 . 
         [0118]    Furthermore, the single tubular introduction portions  75   e  corresponds to the cleaning device  25  that performs cleaning on the intermediate transfer belt  21 , which transfers the toner images of four colors, and the end portion  81   a  of the conduit tube  81  of the toner recovery portion  73  on the side of the cleaning device  25  is inserted into the tubular introduction portion  75   e.  The conduit tube  81  of this toner recovery portion  73  is arranged along the main scanning direction of the intermediate transfer belt  21 , and is provided with open slits (not shown in drawings) along this main scanning direction. The toner that is removed from the surface of the intermediate transfer belt  21  by a blade or the like of the cleaning device  25  is disposed into the conduit tube  81  via these open slits. The transport screw  82  is rotationally driven in one direction inside the conduit tube  81 , and the toner inside the conduit tube  81  is transported (drawn out) in the direction of the tubular introduction portion  75   e  of the upper side container  72 - 1 . 
         [0119]    Inside each of the tubular introduction portions  75   a  to  75   e,  the end portion  81   a  of each of the conduit tubes  81  is rotatable, and a disposal hole  83  is formed in a lateral wall of each of the end portions  81   a  respectively, while the end surface of each of the end portions  81   a  is closed. Furthermore, a disposal hole  84  is formed in the lateral wall of each of the tubular introduction portions  75   a  to  75   e  respectively. In a state in which the end portion  81   a  of each of the conduit tubes  81  is rotated such the disposal hole  83  of the end portion  81   a  of each of the conduit tubes  81  is superimposed on the disposal hole  84  of each of the tubular introduction portions  75   a  to  75   e  respectively, the toner that is transported in by its respective transport screw  82  is discharged to the upper side container  72 - 1  through the discharge holes  83  and  84 , and this toner drops and is accommodated inside the lower side container  72 - 2  via the bottom side opening portion  76  of the upper side container  72 - 1  and the upper side opening portion  78  of the lower side container  72 - 2 . 
         [0120]    Furthermore, in a state in which the end portion  81   a  of each of the conduit tubes  81  is rotated such that the disposal hole  83  of the end portion  81   a  of each of the conduit tubes  81  is displaced from the disposal hole  84  of each of the tubular introduction portions  75   a  to  75   e,  the toner inside each of the conduit tubes  81  does not discharge through the disposal holes  83  and  84 . In this state, the upper side container  72 - 1  or the lower side container  72 - 2  is replaced. 
         [0121]    As shown in  FIGS. 3 and 4 , the agitator blades  77  are axially supported so as to be rotatably on a shaft  77   a  that spans across the bottom side opening portion  76  of the upper side container  72 - 1 , and a gear  85  that is secured at one end of the shaft  77   a  meshes with an output gear  92  of the rotational drive unit UN. The gear  85  is rotationally driven by the rotational drive unit UN, and the shaft  77   a  rotates due to this rotational drive through the gear  85 . Due to the rotation of the shaft  77   a,  the agitator blades  77  agitate and spread the toner that has dropped down from the disposal hole  84  of each of the tubular introduction portions  75   a  to  75   e,  thereby making uniform the height of the surface of the toner collected in the bottom of the lower side container  72 - 2 . 
         [0122]    It should be noted that the transport screw  82  inside each of the conduit tubes  81  is rotationally driven by a power source on the cleaning devices  14  and  25  side. Furthermore, although a mechanism for rotating the end portion  81   a  of each of the conduit tubes  81  is not shown, the end portion  81   a  of each of the conduit tubes  81  is rotated manually. 
         [0123]    Next, detailed description is given regarding the rotational drive unit UN.  FIGS. 5 and 6  are perspective views of the rotational drive unit UN, as viewed from the front and as viewed from behind. Furthermore,  FIG. 7  is a front view showing the rotational drive unit UN. 
         [0124]    As shown in  FIGS. 5 to 7 , the rotational drive unit UN is provided with components such as a movable lever portion  91 , the output gear (second rotation member)  92 , an input gear  93 , a worm gear  94 , a coupling gear  95 , a coupling flange (first rotation member)  96 , a coil spring  97 , a switch  98 ., a knob  99 , and a frame  101 . 
         [0125]    The frame  101  is provided with a central upper side wall portion  102 , a central lower side wall portion  103 , and two lateral wall portions  104  and  105 , and a bottom portion  106 . 
         [0126]    A shaft hole  91   b  is formed in the movable lever portion  91 , and a shaft  103   a  of the central lower side wall portion  103  of the frame  101  passes through the shaft hole  91   b  such that the movable lever portion  91  is supported so as to be rotatable around the shaft  103   a.  As shown in  FIG. 5  and  FIG. 7 , a protrusion  91   d  is formed in a recess  91   c  of the movable lever portion  91 . Ends of a coil spring  112  are fitted into the protrusion  91   d  of the movable lever portion  91  and a protrusion  106   a  of the bottom portion  106  of the frame  101 . The coil spring  112  is pressed by the movable lever portion  91 , and due to this compressed coil spring  112 , the movable lever portion  91  is biased in a clockwise direction (upward direction in  FIG. 7 ) centered on the shaft  103   a.    
         [0127]    Furthermore, as shown in  FIG. 5  and  FIG. 7 , the switch  98  is secured at one surface of the movable lever portion  91  (the rear surface side wall portion), and a movable piece  98   a  of the switch  98  protrudes upward. The switch  98  has a spring (not shown in drawings) that biases the movable piece  98   a  rightward (one direction) and due to the spring, the switch  98  is off when the movable piece  98   a  is displaced rightward (one direction) and is on when the movable piece  98   a  resists the biasing force of the spring to be displaced leftward (other direction, which is a direction opposite to the one direction). In  FIG. 7 , the switch  98  is on. 
         [0128]    As shown in  FIG. 6 , the knob  99  is biased by a coil spring  113  so that the knob  99  protrudes outward from the central lower side wall portion  103  to the near side of the paper plane. 
         [0129]    In  FIGS. 5 to 7 , the knob  99  is resisting the biasing force of the coil spring  113  and is pushing to the central lower side wall portion  103  side. This is related to the fact that an engaging portion  91   e  of the movable lever portion  91  has shifted from a horizontal state to the central lower side wall portion  103  side by rotating clockwise centered on the shaft  103   a.  In this way, the movable lever portion  91  rotates in the clockwise direction (upward direction in  FIG. 7 ) until the engaging portion  91   e  of the movable lever portion  91  contacts the outer circumference of the knob  99 , and therefore the lever  91   a  of the movable lever portion  91  is held up as shown in  FIG. 7 . Furthermore, at this time, the movable piece  98   a  of the switch  98  contacts the coupling flange  96  and displaces leftward (other direction) such that the switch  98  becomes on. 
         [0130]    As shown in  FIGS. 5 to 7 , the input gear  93  and the worm gear  94  are secured to ends of a shaft  111 . The shaft  111  passes through a shaft hole (not shown in drawings) of the central upper side wall portion  102  of the frame  101  to axially support both the input gear  93  and the worm gear  94 , and the worm gear  94  meshes with the coupling gear  95 . 
         [0131]    The output gear  92 , the coupling gear  95 , and the coupling flange  96  share a common shaft (shaft center) and engage with each other (for example, see  FIG. 8 ). The coil spring  97  is compressed and interposed between the output gear  92  and the coupling flange  96 . 
         [0132]    As shown in  FIG. 5 ,  FIG. 7 , and  FIG. 8 , the output gear  92  is provided with a tubular shaft  92   a,  and this tubular shaft  92   a  is inserted into a shaft hole of the lateral wall portion  104  and is supported so as to be readily rotatable. Furthermore, the output gear  92  presses against the lateral wall portion  104 , and the axial direction of the output gear  92  is determined by this pressing, thereby positioning the output gear  92 . 
         [0133]    As shown in  FIG. 5 ,  FIG. 7 , and  FIG. 8 , the coupling gear  95  is provided with a tubular shaft  95   a,  and this tubular shaft  95   a  is inserted into a shaft hole of the lateral wall portion  105  and is supported so as to be readily rotatable. Furthermore, a convex portion  95   b  of the coupling gear  95  presses against the lateral wall portion  105 , and the axial direction of the coupling gear  95  is determined by this pressing, thereby positioning the coupling gear  95 . 
         [0134]    As shown in  FIG. 5 ,  FIG. 7 , and  FIG. 8 , respective ends of the shaft of the coupling flange  96  are inserted into and are supported by the shaft hole of the output gear  92  and the shaft hole of the coupling gear  95 . The coupling flange  96  rotates together with the output gear  92  and is capable of moving in the axial direction with respect to the output gear  92 . 
         [0135]      FIG. 8A  is a cross-sectional view showing an enlargement of the output gear  92 , the coupling gear  95 , the coupling flange  96 , and the coil spring  97 .  FIG. 8B  is a top view showing the output gear  92  and other components. 
         [0136]    As is evident from  FIG. 8A  and  FIG. 8B , a shaft  96   a  is provided in the center of the coupling flange  96 , the left side of the shaft  96   a  (side where the output gear  92  is positioned) is inserted into a shaft hole  92   b  of the output gear  92  so as to be readily movable, and a claw  96   b  on the left end of the shaft  96   a  catches onto a peripheral edge of the shaft hole  92   b  of the output gear  92 . 
         [0137]    The coupling flange  96  is capable of moving in a left direction in which the claw  96   b  of the shaft  96   a  moves apart from the peripheral edge of the shaft hole  92   b  of the output gear  92 , and is capable of moving in a right direction until the claw  96   b  of the shaft  96   a  catches onto the peripheral edge of the shaft hole  92   b  of the output gear  92 , and moves together with the shaft  96   a.  Furthermore, due to the claw  96   b  of the shaft  96   a  of the coupling flange  96 , the output gear  92  is prevented from coming off the shaft  96   a.    
         [0138]    Furthermore, a pair of curved guide ribs  96   c,  which are provided protruding at the left side lateral surface of the coupling flange  96 , are inserted into a pair of curved grooves  92   c  that are formed around the shaft hole  92   b  of the output gear  92 . Due to the engaging of these curved guide ribs  96   c  and curved grooves  92   c,  the coupling flange  96  and the output gear  92  rotate together. 
         [0139]    Further still, the right side of the shaft  96   a  of the coupling flange  96  (the side where the coupling gear  95  is positioned) is inserted into a shaft hole  95   c  of the coupling gear  95  so as to be readily movable and readily rotatable. 
         [0140]    The coil spring  97  compresses and is inserted between the coupling flange (first rotation member)  96  and the output gear (second rotation member)  92 . Due to the coil spring  97 , the output gear  92  is biased to the left direction along the shaft  96   a  of the coupling flange  96  and presses against the lateral wall portion  104  (shown in  FIG. 7 ) to be positioned. Furthermore, due to the coil spring  97 , the coupling flange  96  is biased to the right direction along the shaft  96   a  of the coupling flange  96  along with the coupling gear  95  such that the coupling gear  95  presses against the lateral wall portion  105  (shown in  FIG. 7 ) to be positioned. 
         [0141]    Furthermore, the coil spring  97  biases the coupling flange  96  with respect to the output gear  92  in the right direction (the direction of the coupling gear  95 ). 
         [0142]    Mutually engaging mountain-valley shaped cams  95   d  and  96   d  are formed at opposing end portions of the coupling gear  95  and the coupling flange  96 . Since the coupling flange  96  is biased by the coil spring  97  with respect to the output gear  92  in the right direction, the coupling flange  96  is biased so as to approach the coupling gear  95 . Due to the biasing of the coupling flange  96 , the cam  95   d  and the cam  96   d  mutually mesh and engage, thereby joining between the tubular shaft  95   a  of the coupling gear  95  and the shaft  96   a  of the coupling flange  96 . When the coupling gear  95  rotates in this joined state, the coupling flange  96  rotates such that the output gear  92  also rotates following the rotation of the coupling flange  96 . 
         [0143]    Furthermore, as is also described later, with the rotational drive unit UN, in a state where an overload is exerted on the output gear  92 , it becomes difficult for the coupling flange  96  and the output gear  92  to rotate. Thus, even though the coupling gear  95  and the cam  95   d  rotate, the coupling flange  96  and the cam  96   d  do not rotate, and the cam  95   d  and the cam  96   d  slip such the connection between the tubular shaft  95   a  of the coupling gear  95  and the shaft  96   a  of the coupling flange  96  is disjoined. In this disjoined state, the coupling flange  96  and the output gear  92  do not rotate and go into a stopped state. 
         [0144]    In this way, the cam  95   d  of the coupling gear  95 , the cam  96   d  of the coupling flange  96 , and the coil spring  97  constitute the torque limiter. 
         [0145]    As shown in  FIG. 8 , in the thus-configured rotational drive unit UN, the coupling flange  96  and the output gear  92  rotate together due to the engaging of the curved guide ribs  96   c  and the curved grooves  92   c,  and since the coil spring  97  is squeezed between the coupling flange  96  and the output gear  92 , the coil spring  97  also rotates together with the coupling flange  96  and the output gear  92 . For this reason, the biasing force of the coil spring  97  is maintained stably without twisting of the coil spring  97 , and the overload on the output gear  92  is also stabilized when the cam  95   d  and the cam  96   d  slip such that the connection of the shafts  95   a  and  96   a  is disjoined. 
         [0146]    In this regard, in the developer recovery device  71  according to the present embodiment, based on the on-off state of the switch  98  of the movable lever portion  91 , determinations are performed as to the state of attachment/detachment of the toner recovery container  72  to the image forming apparatus  1 , the full state in which the toner recovery container  72  is full of toner recovered in the developer recovery device  71 , or a malfunction state of the developer recovery device  71 . 
         [0147]      FIG. 9  is a block diagram showing a configuration of a control system that carries out determinations such as these. In  FIG. 9 , a control portion  121  monitors the on-off state of the switch  98  and, based on the on-off state of the switch  98 , determines the state of attachment/detachment of the toner recovery container  72 , the full state of the toner recovery container  72 , or the malfunction state of the developer recovery device  71 , and displays the determination result on a display portion  122 . 
         [0148]    First, when the toner recovery container  72  shown in  FIG. 2  for example is arranged at a near side space inside the image forming apparatus  1  (see the dashed line region of reference symbol  71  shown in  FIG. 1 ), the gear  85  that is secured to one end of the shaft  77   a  of the agitator blades  77  of the toner recovery container  72  meshes with the output gear  92  of the rotational drive unit UN. Furthermore, the protruding portion  72   e  of the bottom side right end of the lower side container  72 - 2  is placed on a lever  91   a  of the rotational drive unit UN, which is provided on the image forming apparatus  1  side, thereby pressing down on the lever  91   a.  That is, as shown in  FIG. 10 , the movable lever portion  91  rotates in a counterclockwise direction on the shaft  103   a  from the state shown in  FIG. 7 . At this time, due to the biasing force of the coil spring  113  (see  FIG. 6 ), the knob  99  protrudes in the bias direction (in  FIG. 10 , toward the near side from the inner side of the paper plane), and a brim  99   b  of the knob  99  moves to the lower side of the engaging portion  91   e  of the movable lever portion  91 . Due to this movement, the engaging portion  91   e  of the movable lever portion  91  engages with the brim  99   b.  That is, due to the brim  99   b  of the knob  99 , the rotational position of the movable lever portion  91  is maintained. Due to the rotation of the movable lever portion  91 , the movable piece  98   a  of the switch  98  provided for the movable lever portion  91  moves apart from the coupling flange  96  and displaces to the right direction (the moving apart direction away from the coupling flange  96 ), and the switch  98  changes from on to off. 
         [0149]    And the control portion  121  deems that the toner recovery container  72  is mounted when the switch  98  changes from on to off and this off state of the switch  98  is maintained. Alternatively, the control portion  121  deems that the toner recovery container  72  is mounted when the switch  98  changes from on to off and this off state of the switch  98  is maintained during powering up of the image forming apparatus  1 . At this time, the control portion  121  carries out control of displaying on the display portion  122  to the effect that the toner recovery container  72  is mounted. 
         [0150]    In this state (a state in which the toner recovery container  72  is mounted in the image forming apparatus  1 ), when the image forming apparatus  1  operates, rotational drive from the drive source of the image forming apparatus  1  is transmitted to the input gear  93  of the rotational drive unit UN, and the input gear  93  is rotationally driven such that the worm gear  94  also rotates. Then, when the worm gear  94  rotates, the coupling gear  95  rotates. When rotation of the coupling gear  95  commences, since the cam  95   d  of the coupling gear  95  and the cam  96   d  of the coupling flange  96  are engaged, the coupling flange  96  and the output gear  92  rotate. The gear  85  of the agitator blades  77  that meshes with the output gear  92  rotates due to the rotation of the output gear  92  such that the agitator blades  77  rotate due to the rotation of the gear  85 . Then, due to the rotation of the agitator blades  77 , the toner that has dropped to the lower side container  72 - 2  of the toner recovery container  72  is agitated, thereby making uniform the height of the surface of the toner collected in the bottom of the lower side container  72 - 2 . 
         [0151]    Accordingly, the control portion  121  deems that the toner recovery container  72  is not in a full state when the off state of the switch  98  continues to be maintained. 
         [0152]    Next, when the lower side container  72 - 2  of the toner recovery container  72  becomes full of toner, the agitator blades  77  become buried in toner and it becomes difficult for them to rotate such that an overload is exerted on the agitator blades  77 . In this state, an overload is also exerted on the output gear  92  that meshes with the gear  85  of the agitator blades  77  such that it is difficult for the output gear  92  and the coupling flange  96  to rotate. At this time, as shown in  FIG. 11 , even though the coupling gear  95  and the cam  95   d  rotate, the coupling flange  96  and the cam  96   d  do not rotate, and the cam  95   d  and the cam  96   d  slip. Due to the slipping of the cam  95   d  and the cam  96   d,  the connection between the tubular shaft  95   a  of the coupling gear  95  and the shaft  96   a  of the coupling flange  96  is disjoined such that the coupling flange  96  and the output gear  92  stop rotation in cooperation with the coupling gear  95 , and the coupling flange  96  and the output gear  92  go into a stopped state. 
         [0153]    In a state where the coupling flange  96  has stopped due to the slipping of the cam  95   d  and the cam  96   d,  the mountain shape of the cam  95   d  and the mountain shape of the cam  96   d  repetitively slide in and out of contact in a periodic manner along with the rotation of the coupling gear  95 . Each time this happens the coupling flange  96  moves in the left direction (the resistance direction with respect to the biasing force) in resistance to the biasing force of the coil spring  97 , and the movable piece  98   a  of the switch  98  is pressed by the coupling flange  96  to be displaced to the left direction (resistance direction) such that the switch  98  turns on (see  FIG. 11 ). Furthermore, in a state where the coupling flange  96  has stopped due to the slipping of the cam  95   d  and the cam  96   d,  not only do the mountain shape of the cam  95   d  and the mountain shape of the cam  96   d  repetitively slide in and out of contact, the mountain shape of the cam  95   d  and the valley shape of the cam  96   d,  and the valley shape of the cam  95   d  and the mountain shape of the cam  96   d  repetitively fit together in a periodic manner along with the rotation of the coupling gear  95 . Each time this happens, the coupling flange  96  moves to the right direction (bias direction) due to the biasing force of the coil spring  97 , and the movable piece  98   a  of the switch  98  moves apart from the coupling flange  96  and displaces to the right direction (bias direction) such that the switch  98  turns off (see  FIG. 10 ). In this way, in a state where the coupling flange  96  has stopped due to the slipping of the cam  95   d  and the cam  96   d,  the cam  95   d  (the valley shape and mountain shape of the cam  95   d ) and the cam  96   d  (the valley shape and the mountain shape of the cam  96   d ) repetitively and alternately carry out moving out of contact and fitting together along with the rotation of the coupling gear  95 . 
         [0154]    Based on the on-off states of the switch  98  accompanying the rotation of the coupling gear  95  of the rotational drive unit UN, the control portion  121  determines the state in which the toner recovery container  72  has become full. With the developer recovery device  71 , if the switch  98  periodically changes on/off accompanying rotation of the coupling gear  95 , then it can be deemed there is a state in which the toner recovery container  72  has become full of toner. 
         [0155]    In more detail, suppose the switch  98  is changing on/off as shown in  FIG. 12 , the control portion  121  obtains an on time t 1  in which the switch  98  is on and an off time t 2  in which the switch  98  is off, then determines whether or not the on time t 1  is within a first prescribed time range ta to taa that is set in advance, and determines whether or not the off time t 2  is within a second prescribed time range tb to tbb that is set in advance. Then, if the on time t 1  is within the first prescribed time range ta to taa (ta≦t 1 ≦taa) and if the off time t 2  is within the second prescribed time range tb to tbb (tb≦t 2 ≦tbb), then it determines that there is a state in which the toner recovery container  72  has become full of toner. In this way, it can be accurately determined that the toner recovery container  72  is in a full state. 
         [0156]    Here, when the toner recovery container  72  is not in a full state but is close to a full state, the load on the agitator blades  77  increases close to an overload such that the engagement state between the cam  95   d  of the coupling gear  95  and the cam  96   d  of the coupling flange  96  becomes unstable, and sometimes the switch  98  turns on and off irregularly. For this reason, there is a possibility of false determinations when determining if the recovery container  72  is in a full state based only on the on/off changing of the switch  98 . 
         [0157]    However, with the present embodiment, when the on time t 1  of the switch  98  is within the first prescribed time range ta to taa (ta≦t 1 ≦taa) and the off time t 2  of the switch  98  is within the second prescribed time range tb to tbb (tb≦t 2 ≦tbb), then it is determined that there is a state in which the toner recovery container  72  has become full of toner, and therefore there are no false determinations. 
         [0158]    For example, when the engagement state between the cam  95   d  of the coupling gear  95  and the cam  96   d  of the coupling flange  96  becomes unstable, the on time or the off time of the switch  98  becomes too short or too long such that the on time t 1  is outside the first prescribed time range ta to taa&lt;ta or taa&lt;t 1 ) or the off time t 2  is outside the second prescribed time range tb to tbb (t 2 &lt;tb or tbb&lt;t 2 ), and therefore it is not determined that the toner recovery container  72  is in a full state. 
         [0159]    Alternatively, supposing the switch  98  changes on/off as shown in FIG.  12 , the control portion  121  repetitively obtains an on/off period T of the switch  98 , and determines whether or not this on/off period T is within a prescribed time range Tc to Tcc and whether or not it has repeated continuously for a prescribed number of times N (for example, N=3) or more. Then, if the on/off period T is within the prescribed time range Tc to Tcc (Tc≦T≦Tcc) and if the on/off periods within the prescribed time range Tc to Tcc have repeated continuously for three times or more, then it determines that there is a state in which the toner recovery container  72  has become full of toner. In this way, it can be accurately determined that the toner recovery container  72  is in a full state. It should be noted that in the present embodiment the prescribed number of times is set to three times, but the number of times may be set to five times for example and can be set arbitrarily. 
         [0160]    In this case also there are no false determinations as to whether or not the toner recovery container  72  is in a full state. For example, when the engagement state between the cam  95   d  of the coupling gear  95  and the cam  96   d  of the coupling flange  96  becomes unstable, the on/off period T fluctuates wildly and is outside the prescribed time range Tc to Tcc (T&lt;Tc or Tcc&lt;T), and the on/off period T does not repeat three times or more within the prescribed time range Tc to Tcc, and therefore it is not determined that the toner recovery container  72  is in a full state. 
         [0161]    When the control portion  121  determines that the toner recovery container  72  is in a full state in this manner, a message to the effect of prompting replacement of the toner recovery container  72  is displayed on the display portion  122 . A user sees this display and replaces the toner recovery container  72  with a new container. 
         [0162]    Next, with reference to  FIG. 2 , if the toner recovery container  72  has been removed for replacement, the protruding portion  72   e  at the bottom side right edge of the lower side container  72 - 2  comes away from the lever  91   a  of the rotational drive unit UN. Then, as shown in  FIGS. 5 to 7 , if the knob  99  is pressed, the movable lever portion  91  rotates in a clockwise direction until the engaging portion  91   e  of the movable lever portion  91  contacts the outer periphery of the knob  99  such that the lever  91   a  of the movable lever portion  91  rises up and the movable piece  98   a  of the switch  98  contacts the coupling flange  96  and displaces to the left direction, and the switch  98  turns on. 
         [0163]    In this state, the coupling flange  96  does not move to the right direction regardless of whether the rotational drive unit UN is operating or stopped, and therefore the movable piece  98   a  of the switch  98  does not displace to the right direction and the on state of the switch  98  continues to be maintained. 
         [0164]    Accordingly, in this case, if the on state of the switch  98  is maintained, it can be deemed that the toner recovery container  72  has been removed. 
         [0165]    Next, at a time when the input gear  93  of the rotational drive unit UN is rotating, if the switch  98  changes from off→on→off as shown in  FIG. 13  and the off state after this change continues for no less than a malfunction determination time Tt that is set in advance, then the control portion  121  determines that a malfunction has occurred in the developer recovery device  71 . 
         [0166]    If the toner recovery container  72  is not in a full state, the cam  95   d  of the coupling gear  95  and the cam  96   d  of the coupling flange  96  are engaged and the agitator blades  77  continue to rotate, and therefore the switch  98  does not change. Furthermore, when the toner recovery container  72  becomes full, the cam  95   d  of the coupling gear  95  and the cam  96   d  of the coupling flange  96  slip such that the connection between the tubular shaft  95   a  of the coupling gear  95  and the shaft  96   a  of the coupling flange  96  disjoins and the switch  98  repetitively turns on and off, and therefore there is no long continuation of either the on or off state. Accordingly, at a time when the input gear  93  of the rotational drive unit UN is rotating, if the switch  98  changes from off→on→off and the off state after this change continues for no less than the malfunction determination time Tt, then it can be determined that a malfunction has occurred in the developer recovery device  71 . 
         [0167]    In this way, in the rotational drive unit UN of the developer recovery device according to the present embodiment, a torque limiter is provided in which the coil spring  97  is squeezed between the coupling flange (first rotation member)  96  and the output gear (second rotation member)  92 , the coupling flange  96  is biased by the coil spring  97  in the right direction (the direction of the coupling gear  95 ) with respect to the output gear  92  such that the cam  96   d  of the coupling flange  96  and the cam  95   d  of the coupling gear  95  are caused to engage, and a connection is joined between the tubular shaft  95   a  of the coupling gear  95  and the shaft  96   a  of the coupling flange  96 . 
         [0168]    For this reason, if the lower side container  72 - 2  of the toner recovery container  72  is not full of toner and an overload is not exerted on the agitator blades  77 , then the cam  96   d  of the coupling flange  96  and the cam  95   d  of the coupling gear  95  engage such that rotational force is transmitted in order from the coupling gear  95 , to the coupling flange  96 , to the output gear  92 , and to the gear  95 , thereby rotating the agitator blades  77 . Furthermore, when the lower side container  72 - 2  becomes full of toner and an overload is exerted on the agitator blades  77 , an overload is also exerted on the output gear  92  and the coupling flange  96  such that the cam  96   d  of the coupling flange  96  and the cam  95   d  of the coupling gear  95  slip resisting the biasing force of the coil spring  97 , and the connection between the tubular shaft  95   a  of the coupling gear  95  and the shaft  96   a  of the coupling flange  96  disjoins, and the agitator blades  77  stop. 
         [0169]    And in the present embodiment, the switch  98  is provided that turns on/off in response to the engaging and moving apart of the cam  96   d  of the coupling flange  96  and the cam  95   d  of the coupling gear  95 , and based on the on-off state of the switch  98  it is determined whether or not the toner recovery container  72  is full of toner. That is, the switch  98  is provided that turns on/off in response to the engaging and moving apart of the cam  96   d  of the coupling flange  96  and the cam  95   d  of the coupling gear  95 , the on time t 1  in which the switch  98  is on and the off time t 2  in which the switch  98  is off are obtained, and if the on time t 1  is within the first prescribed time range ta to taa (ta≦t 1 ≦taa) and the off time t 2  is within the second prescribed time range tb to tbb (tb≦t 2 ≦tbb), then it is determined that there is a state in which the toner recovery container  72  has become full of toner. Alternatively, if the on/period T is within the prescribed time range Tc to Tcc (Tc≦T≦Tcc) and if the on/off periods within the prescribed time range Tc to Tcc have repeated continuously for three times or more, then it determines that there is a state in which the toner recovery container  72  has become full of toner. Thus, it can be accurately determined that the toner recovery container  72  is in a full state. 
         [0170]    Furthermore, at a time when the input gear  93  of the rotational drive unit UN is rotating, when the switch  98  changes from on to off and the off state after this change continues for no less than the malfunction determination time Tt, then it is determined that a malfunction has occurred in the developer recovery device  71 . 
         [0171]    Furthermore, the coupling flange  96  and the output gear  92  rotate together, and the coil spring  97  squeezed between the coupling flange  96  and the output gear  92  also rotates together, and therefore there is no twisting of the coil spring  97  and the biasing force of the coil spring  97  with respect to the coupling flange  96  is stabilized. For this reason, the overload on the output gear  92  and the agitator blades  77  is stabilized when the cam  96   d  of the coupling flange  96  and the cam  95   d  of the coupling gear  95  slip such that the connection between the cams  95   a  and  96   a  disjoins, and based on the on-off state of the switch  98 , the determination of the full state of the lower side container  72 - 2  becomes accurate such that the replacements of the toner recovery container  72  can be carried out with appropriate timings. 
         [0172]    Furthermore, no extra load is exerted on either the coupling flange  96  or the output gear  92  such that the durability of the device can be improved without causing wear to coupling flange  96  and the output gear  92 . 
         [0173]    The foregoing described preferable embodiments of the present invention with reference to the accompanying drawings, but the present invention is not limited to these examples. It is evident that a person skilled in the art would be capable of conceiving various modifications and alterations within the scope described by the claims, and naturally all of these are to be interpreted as belonging to the technical scope of the present invention. 
         [0174]    For example, the relationship between the left-right displacement direction of the movable piece  98   a  of the switch  98  and the on-off state of the switch  98  may be reversed. 
         [0175]    That is, the present invention can be embodied and practiced in other different forms without departing from the spirit, purport or essential characteristics thereof. Therefore, the above-described embodiments are considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description. All variations and modifications falling within the equivalency range of the appended claims are intended to be embraced therein.