Abstract:
A driving force transmission mechanism includes a body that includes a transmission member, which transmits a driving force and includes a rotatable first surface and two first projections, and an installation unit that includes a receiving member including a second surface, which faces the first surface and which is rotatable by receiving the force when the installation unit is installed, and two second projections, which receive the force from the first projections by contacting the first projections when the first surface rotates, and that is removably installed in the body in a direction, in which the second surface moves parallel to the first surface, to couple the transmission member and the receiving member. The body includes a contact member that contacts, to rotate the receiving member, one of the second projections when the installation unit is installed while a line segment connecting the second projections is intersecting an installation direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2015-060287 filed Mar. 24, 2015. 
     
    
     BACKGROUND 
       [0002]    Technical Field 
         [0003]    The present invention relates to a driving force transmission mechanism and an image forming apparatus. 
       SUMMARY 
       [0004]    According to an aspect of the invention, there is provided a driving force transmission mechanism including a body including a transmission member that transmits a driving force and includes a first surface, which rotates, and two first projections that project from the first surface at positions, each of which is spaced apart from a center of rotation of the first surface and an installation unit that includes a receiving member including a second surface, which faces the first surface and which rotates as a result of receiving the driving force in a state where the installation unit is installed in the body, and two second projections, which project from the second surface at positions each of which is spaced apart from a center of rotation of the second surface and which receive the driving force from the first projections by being in contact with the first projections in accordance with rotation of the first surface, and that is configured to be removably installed in the body in a direction in which the second surface moves parallel to the first surface in such a manner that the transmission member and the receiving member are coupled to each other. The body further includes a contact member that is brought into contact with one of the second projections when the installation unit is installed in the body in a state where a line segment connecting the second projections intersects an installation direction in which the installation unit is installed in the body and that causes the receiving member to rotate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein: 
           [0006]      FIG. 1  is a schematic diagram illustrating a printer, which is an exemplary embodiment of an image forming apparatus of the present invention; 
           [0007]      FIG. 2  is a diagram illustrating a transmission member mounted on a printer body; 
           [0008]      FIG. 3  is a diagram illustrating a receiving member mounted on a toner cartridge; 
           [0009]      FIGS. 4A to 4C  are schematic diagrams illustrating a state in which the receiving member comes closer to the transmission member as a result of an operation of installing the toner cartridge; 
           [0010]      FIGS. 5A and 5B  are schematic diagrams respectively illustrating the receiving member and the transmission member; 
           [0011]      FIG. 6  is a diagram illustrating a problem that may occur in the case where the distance between two first projections and the distance between two second projections are approximately equal to each other; 
           [0012]      FIG. 7A and 7B  are schematic diagrams illustrating how to address the disadvantage illustrated in  FIG. 6 ; and 
           [0013]      FIG. 8  is a diagram illustrating the case of addressing the disadvantage illustrated in  FIG. 6  in the manner illustrated in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    An exemplary embodiment of the present invention will be described below. 
         [0015]      FIG. 1  is a schematic diagram illustrating a printer, which is an exemplary embodiment of an image forming apparatus of the present invention. A device, which is an exemplary embodiment of a driving force transmission device of the present invention, is incorporated within the printer. 
         [0016]    A printer  1  illustrated in  FIG. 1  is a printer that employs an electrophotographic system and prints an image on one of sheets P, and a side surface of the printer  1  on the right side in  FIG. 1  is a front surface of the printer  1 . In the printer  1 , a process cartridge  2  is installed in a printer body  11  so as to be removable from the printer body  11  on the side on which the front surface of the printer  1  is present. In addition, a toner cartridge  3  is installed diagonally above a front surface of the process cartridge  2  so as to be removable from the printer body  11  on the side on which the front surface of the printer  1  is present. 
         [0017]    Here, the printer body  11  corresponds to an example of a body, and the toner cartridge  3  corresponds to an example of an installation unit. 
         [0018]    The toner cartridge  3  contains a replenishing toner, and this toner in the toner cartridge  3  is stirred as a result of rotation of a stirring member  31 , so that the toner is prevented from coagulating. A driving force is transmitted to the stirring member  31  from a motor  111 , which is provided in the printer body  11 , via a driving force transmission mechanism (not illustrated). The toner in the toner cartridge  3  is supplied to a developing unit  21 , which is included in the process cartridge  2 . 
         [0019]    In addition to the developing unit  21 , the process cartridge  2  includes a photoconductor  22 , a charger  23 , and a cleaner  24 . A waste-toner containing chamber  25  that contains waste toner, which is scraped off from the photoconductor  22  by the cleaner  24 , is disposed between the developing unit  21  and the photoconductor  22  and the toner cartridge  3 . 
         [0020]    The printer body  11  further includes an exposure unit  112  that radiates exposure light  112   a  onto the photoconductor  22  and a transfer unit  113  that is disposed at a position facing the photoconductor  22 . 
         [0021]    The photoconductor  22  is subjected to various operations described below while rotating in the direction of arrow A. 
         [0022]    The charger  23  charges a surface of the photoconductor  22  to a predetermined potential. 
         [0023]    The exposure unit  112  radiates the exposure light  112   a,  which corresponds to an image signal, onto the charged surface of the photoconductor  22  so as to form an electrostatic latent image on the surface of the photoconductor  22 . 
         [0024]    The developing unit  21  contains a developer containing a carrier and a toner and moves circularly in a direction perpendicular to  FIG. 1  as a result of rotation of two augers  211  and  212 . The developer in the developing unit  21  is delivered to a developing position facing the photoconductor  22  by a developing roller  213  that rotates in the direction of arrow B. An electrostatic latent image on the photoconductor  22  is developed with the toner, which is contained in the developer, and a toner image is formed on the photoconductor  22 . The toner image formed on the photoconductor  22  is transferred onto one of the sheets P, which is transported in a manner described later, by operation of the transfer unit  113 . The toner image on the sheet P is heated and pressurized by a fixing unit  114  provided in the printer body  11  and fixed onto the sheet P. 
         [0025]    A sheet cartridge  115  is mounted in a lower portion of the printer body  11  in such a manner as to be capable of being drawn out toward the right side in  FIG. 1 , and the sheets P, on each of which an image is to be printed, are accommodated in the sheet cartridge  115  in such a manner as to be stacked on top of one another. When a printing operation is performed, one of the sheets P accommodated in the sheet cartridge  115 , the sheet P being at the top of the sheets P, is taken out by a take-out roller  116 . Even in the case where some of the sheets P are taken out while superposed with each other, separation rollers  117  separate the sheets P one by one with certainty, and only one of the sheets P is transported along a transport path d 1  and reaches registration rollers  118 . The registration rollers  118  correct the position of the sheet P, which has been transported, and send out the sheet P to a further downstream side by adjusting the timing of subsequent transportation of the sheet P. The registration rollers  118  send out the sheet P in accordance with the timing at which the toner image on the photoconductor  22  is transferred, and the toner image on the photoconductor  22  is transferred onto the sheet P. The sheet P, to which the toner image has been transferred, is further transported along a transport path d 2  in such a manner as to pass through the fixing unit  114 , the toner image is fixed onto the sheet P. The sheet P is ejected by sheet ejection rollers  119  into a sheet-ejection tray  120  that is provided in an upper portion of the printer body  11 . 
         [0026]    In the case of printing an image on the two surfaces of the sheet P, a portion of the sheet P, which has an image printed on one surface thereof in a similar manner to the above, is sent out by the sheet ejection rollers  119 . After that, the sheet ejection rollers  119  rotate in a reverse direction, and the sheet P is transported along a transport path d 3  and reaches the registration rollers  118  again. Subsequently, the above-described printing operation is repeated, and the sheet P having images printed on the two surfaces thereof is ejected into the sheet-ejection tray  120  by the sheet ejection rollers  119 . 
         [0027]    A cover  121 , which is a portion of a cover of the printer body  11 , is capable of being freely opened and closed in the direction of arrow C to arrow D, that is, toward the front surface of the printer  1 , with a hinge portion  121   a  acting as a center. When a user opens the cover  121  and draws out the toner cartridge  3  by holding a handle  39 , which is included on the toner cartridge  3 , in their hand, the toner cartridge  3  is removed from the printer body  11 . When the user removes the process cartridge  2  from the printer body  11 , after the toner cartridge  3  has been removed from the printer body  11 , the user tilts a rotating lever  29 , which is included on the process cartridge  2 , in such a manner that the rotating lever  29  rotates in the direction of arrow E. The rotating lever  29  is rotatably mounted with a hinge portion  29 . However, during the period when the toner cartridge  3  is installed in the printer body  11 , the rotating lever  29  is maintained at a first position, which is illustrated in  FIG. 1 , due to the presence of the toner cartridge  3 . 
         [0028]    When the process cartridge  2  is installed at a normal position, which is illustrated in  FIG. 1 , and the rotating lever  29  is located at the first position illustrated in  FIG. 1 , regardless of the existence of the toner cartridge  3 , part of a lower end portion of the process cartridge  2  is hooked on the printer body  11 , and accordingly, it is difficult to draw out the process cartridge  2 . 
         [0029]    In the case of removing the process cartridge  2  from the printer body  11 , a user removes the toner cartridge  3  first. After that, the user tilts the rotating lever  29  in the direction of arrow E so as to bring the rotating lever  29  to a second position. Then, the process cartridge  2  is slightly raised by an eccentric cam (not illustrated) that is integrally formed with the rotating lever  29 . As a result, the part of the lower end portion of the process cartridge  2 , which has been hooked on the printer body  11 , is released. Finally, the user draws out the process cartridge  2  by using as a handle the rotating lever  29 , which has been tilted so as to be located at the second position as is, and the process cartridge  2  may be removed from the printer body  11 . In the case of installing the process cartridge  2 , the user performs an operation that is the reverse of the operation for removing the process cartridge  2  from the printer body  11 . In other words, the user presses the process cartridge  2  into the printer body  11  by using the rotating lever  29  of the process cartridge  2  as a handle and brings the rotating lever  29  to the first position illustrated in  FIG. 1  by rotating the rotating lever  29  in the direction of arrow F. Then, the part of the lower end portion of the process cartridge  2  is hooked on the printer body  11  and prevented from being released from the printer body  11 . After that, the user installs the toner cartridge  3  into the printer body  11  by holding the handle  39  of the toner cartridge  3  in their hand and closes the cover  121  of the printer body  11  in the direction of arrow D. 
         [0030]    The printer body  11  includes a transmission member that transmits a driving force, which causes the stirring member  31  to rotate, from the motor  111  to the toner cartridge  3 . The toner cartridge  3  includes a receiving member that receives the driving force from the transmission member. 
         [0031]    The structures of the transmission member and the receiving member and a structure associated therewith will be described below. 
         [0032]      FIG. 2  is a diagram illustrating a transmission member mounted on the printer body  11 . 
         [0033]      FIG. 3  is a diagram illustrating a receiving member mounted on the toner cartridge  3 . 
         [0034]    Although the toner cartridge  3  in the printer  1  according to the present exemplary embodiment is configured to be installed in a diagonal direction from a top side to a bottom side as illustrated in  FIG. 1 , for ease of understanding,  FIG. 2  and  FIG. 3  illustrate the toner cartridge  3  as if the toner cartridge  3  is installed in the horizontal direction. 
         [0035]    A transmission member  40  illustrated in  FIG. 2  has a circular-shaped first surface  41 . The first surface  41  receives a driving force from the motor  111  (see  FIG. 1 ) and rotates about a center of rotation  40   a,  which is the center of the first surface  41 . The transmission member  40  includes two first projections  42  projecting from the first surface  41  at positions, each of which is spaced apart from the center of rotation  40   a  of the first surface  41  in opposite directions. These two first projections  42  rotate around the center of rotation  40   a  as a result of rotation of the first surface  41 . In the printer body  11 , a projection  43 , which has a portion on its bottom surface side formed in an arc shape, is disposed at a position closer than the transmission member  40  to the proximal side in an installation direction indicated by arrow G. Operation of the projection  43  will be described later. The projection  43  corresponds to an example of a contact member. 
         [0036]    A receiving member  50 , which is mounted on the toner cartridge  3  and illustrated in  FIG. 3 , has a circular-shaped second surface  51 . When the toner cartridge  3  is installed in the printer body  11 , the second surface  51  is located at a position facing the first surface  41  (see  FIG. 2 ) of the transmission member  40  mounted on the printer body  11 . The second surface  51  receives a driving force from the transmission member  40  of the printer body  11  and rotates about a center of rotation  50   a,  which is the center of the circular shape. 
         [0037]    The receiving member  50  of the toner cartridge  3  includes two second projections  52  projecting from the second surface  51  at positions, each of which is spaced apart from the center of rotation  50   a  of the second surface  51  in substantially opposite directions. Each of the two second projections  52  is brought into contact with a corresponding one of the two first projections  42 , which are included in the transmission member  40  of the printer body  11 . When the transmission member  40  rotates, the two second projections  52  receive a driving force from the corresponding two first projections  42  and rotate upon the rotations of the first projections  42  so that the second surface  51  rotates. This rotation is transmitted to the stirring member  31 , which is disposed in the toner cartridge  3  (see  FIG. 1 ), and consequently, the stirring member  31  rotates. 
         [0038]    Coupling of the receiving member  50  to the transmission member  40  in the case of installing the toner cartridge  3  will now be described. 
         [0039]      FIGS. 4A to 4C  are schematic diagrams illustrating a state in which the receiving member  50  comes closer to the transmission member  40  as a result of an operation of installing the toner cartridge  3 . 
         [0040]    Here, the transmission member  40  of the printer body  11  is stopped at a position where a line segment connecting the two first projections  42  is perpendicular to an insertion direction indicated by arrow G. The receiving member  50  of the toner cartridge  3  is also located at a position where a line segment connecting the two second projections  52  is perpendicular to the insertion direction indicated by arrow G. In the case where both the transmission member  40  and the receiving member  50  are located at the above-mentioned positions, when the toner cartridge  3  is installed in the direction of arrow G without taking any measures, the two second projections  52  abuts against the corresponding two first projections  42  at approximately the same time, and the installation of the toner cartridge  3  is obstructed. As a result, it is difficult to couple the receiving member  50  to the transmission member  40 . Accordingly, in the present exemplary embodiment, in the printer body  11 , the projection  43  is disposed at the position closer than the transmission member  40  to the proximal side in the installation direction (indicated by arrow G) (also see  FIG. 2 ). 
         [0041]    In the case of installing the toner cartridge  3 , as illustrated in  FIG. 4A , the receiving member  50  comes closer to the transmission member  40  in the direction of arrow G. Then, as illustrated in  FIG. 4B , one of the two second projections  52  of the receiving member  50  abuts against the projection  43  of the printer body  11 , and the receiving member  50  rotates in the direction indicated by arrow H. Consequently, as illustrated in  FIG. 4C , the toner cartridge  3  is inserted in such a manner that the second surface  51  reaches the normal position facing the first surface  41  while the second projections  52  avoid making contact with the first projections  42 . 
         [0042]      FIGS. 5A and 5B  are schematic diagrams respectively illustrating the receiving member  50  and the transmission member  40 . 
         [0043]    The shapes of the first projections  42  and the second projections  52  will now be described. 
         [0044]    The transmission member  40  illustrated in  FIG. 5B  will be described first. Surfaces of the two first projections  42  of the transmission member  40  facing the center of rotation  40   a  each have an arc shape. In addition, each of the two first projections  42  has a first pointed portion  42   a,  which is tapered in a direction away from the center of rotation  40   a.    
         [0045]    The two second projections  52  of the receiving member  50  illustrated in  FIG. 5A  are disposed at positions that are slightly offset with respect to the center of rotation  50   a  in order to make a line segment connecting two contact points of the two second projections  52  and the two first projections  42  of the transmission member  40  pass through the center of rotation  50   a.    
         [0046]    Portions of the second projections  52  that come into contact with the corresponding first projections  42  are each formed of a plane that is vertically oriented. On the other hand, each of the first projections  42  is brought into linear contact with the corresponding second projections  52  on a vertical boundary line between the portion of the first projection  42  having an arc shape and the first pointed portion  42   a.  If each of the first projections  42  is formed in a plane so as to be brought into surface contact with the corresponding second projection  52 , contact positions will be displaced to a large extent in a radial direction with small tolerance. In the present exemplary embodiment, in order to suppress this from occurring, the first projections  42  are each formed in such a shape so as to come into linear contact with the corresponding second projection  52 . 
         [0047]    Similar to the first projections  42 , each of the second projections  52  has a first pointed portion  52   a,  which is tapered in a direction away from the center of rotation  50   a.  In addition, each of the second projections  52  has a second pointed portion  52   b,  which is tapered in a direction toward the center of rotation  50   a.    
         [0048]    Here, the transmission member  40  and the receiving member  50  are located at positions where one of the second projections  52  that is positioned further toward the proximal side in the installation direction (direction of arrow G) and one of the first projections  42  that is positioned further toward the distal side in the installation direction (direction of arrow G) are arranged side by side in the installation direction (direction of arrow G). The one of the second projections  52  will hereinafter be referred to as a proximal second projection  52 , and the one of the first projections  42  will hereinafter be referred to as a distal first projection  42 . 
         [0049]    While the transmission member  40  and the receiving member  50  are located at these positions, when the toner cartridge  3  is installed, and the receiving member  50  comes closer to the transmission member  40 , the first pointed portion  52   a  of the proximal second projection  52  abuts against the first pointed portion  42   a  of the distal first projection  42 . Here, since the distal first projection  42  and the proximal second projection  52  have the first pointed portion  42   a,  which is tapered, and the first pointed portion  52   a,  which is tapered, respectively, when the first pointed portion  52   a  comes into contact with the first pointed portion  42   a,  the receiving member  50  rotates in one of two directions. Consequently, when the toner cartridge  3  is inserted further in the installation direction (direction of arrow G), the receiving member  50  and the transmission member  40  are coupled to each other. 
         [0050]    When the receiving member  50  rotates slightly as a result of the proximal second projection  52  coming into contact with the distal first projection  42 , and the toner cartridge  3  is inserted more deeply, or when the transmission member  40  is located at a position where the transmission member  40  reaches after rotating slightly from the position illustrated in  FIG. 5B , and the toner cartridge  3  is inserted more deeply without contact between the proximal second projection  52  and the distal first projection  42 , a situation may be assumed in which the other one of the second projections  52  that is positioned further toward the distal side in the installation direction (direction of arrow G) comes into contact with the distal first projection  42 . The other one of the second projections  52  will hereinafter be referred to as a distal second projection  52 . 
         [0051]    In this case, the second pointed portion  52   b  of the distal second projection  52  facing the center of rotation  50   a  comes into contact with the first pointed portion  42   a  of the distal first projection  42 . Accordingly, also in this case, contact is made between portions each of which is tapered, and when the toner cartridge  3  is inserted further deeply as is, the receiving member  50  and the transmission member  40  are coupled to each other. 
         [0052]    A relationship between the distance between the two first projections  42 , which are included in the transmission member  40 , and the distance between the two second projections  52 , which are included in the receiving member  50 , will now be described. 
         [0053]      FIG. 6  illustrates a comparative example and is a diagram illustrating a problem that may occur in the case where the distance between the two first projections  42  and the distance between the two second projections  52  are approximately equal to each other. 
         [0054]    In order to transmit a driving force from the transmission member  40  to the receiving member  50  by correctly coupling the transmission member  40  and the receiving member  50  to each other, it is necessary that the two second projections  52  of the receiving member  50  move to positions opposite to each other with respect to the corresponding two first projections  42  of the transmission member  40  (on the same side in a rotation direction of the receiving member  50 ). 
         [0055]    Here, as illustrated in  FIG. 6 , the two first projections  42  and the two second projections  52  are positioned so as to be inclined to the installation direction (direction of arrow G). 
         [0056]    In this case, the proximal second projection  52  (the second projection  52  in the lower right of  FIG. 6 ) abuts against a surface of the other one of the first projections  42  that is positioned further toward the proximal side in the installation direction (the first projection  42  in the lower right of  FIG. 6 ), the surface being located on the downstream side in a rotation direction of the transmission member  40  (direction indicated by arrow I). The other one of the first projections  42  will hereinafter be referred to as a proximal first projection  42 . Then, the receiving member  50  tries to rotate in a direction indicated by arrow H. However, the distal second projection  52  (the second projection  52  in the upper left of  FIG. 6 ) abuts against the distal first projections  42  (the first projection  42  in the upper left of  FIG. 6 ) this time, and it is difficult to correctly couple the transmission member  40  and the receiving member  50  to each other. 
         [0057]      FIG. 7  is a schematic diagram illustrating how to address the disadvantage illustrated in  FIG. 6 . 
         [0058]    Here, a distance between a first end of one of the two first projections  42 , the first end being further away from the center of rotation  40   a  than a second end of the first projection  42 , and a first end of the other one of the first projections  42 , the first end being closer to the center of rotation  40   a  than a second end of the first projection  42 , is a first distance a. A distance between a first end of one of the two second projections  52 , the first end being further away from the center of rotation  50   a  than a second end of the second projection  52 , and a first end of the other one of the second projections  52 , the first end being closer to the center of rotation  50   a  than a second end of the second projection  52 , is a second distance b. When the first distance a and the second distance b are compared, a relationship of a&gt;b is satisfied. However, since this is an outline of how to address the disadvantage illustrated in  FIG. 6 , there is a case where desirable results are not obtained even if the relationship of a&gt;b is barely satisfied. Therefore, it is necessary that the difference between the first distance a and the second distance b be slightly larger in order to satisfy a relationship of a&gt;b+c (c&gt; 0 ). 
         [0059]      FIG. 8  is a diagram illustrating the case of addressing the disadvantage illustrated in  FIG. 6  in the manner illustrated in  FIG. 7 . 
         [0060]    In  FIG. 8 , regarding the transmission member  40  and the receiving member  50 , the two first projections  42  and the two second projections  52  are positioned so as to be oriented as illustrated in  FIG. 8 . 
         [0061]    Assume that the toner cartridge  3  is installed in the installation direction (direction of arrow G), and the distal second projection  52  (the second projection  52  on the left side in  FIG. 8 ) comes into contact with the distal first projections  42  (on the left side in  FIG. 8 ) at a contact point X. Then, the receiving member  50  rotates in a direction indicated by arrow J. Here, a circle R 2  having a diameter equal to a distance b′ between the contact point X and a first end of the proximal second projection  52  (on the right side in  FIG. 8 ), the first end being closer to the center of rotation  50   a  than a second end of the proximal second projection  52 , is smaller than a circle R 1  having a diameter equal to a distance a′ between the contact point X and a first end of the proximal first projections  42  (on the right side in  FIG. 8 ), the first end being closer to the center of rotation  40   a  than a second end of the proximal first projection  42 . In other words, a relationship of a′&gt;b′ is satisfied. 
         [0062]    Note that, although in the present exemplary embodiment, the printer  1  has been described as an example of the driving force transmission device of the present invention, the present invention is not limited to the printer  1  and image forming apparatuses other than the printer  1  and may be widely applied to apparatuses each of which includes a body, which transmits a driving force, and an installation unit, which receives the driving force by being installed in the body. 
         [0063]    The foregoing description of the exemplary embodiment of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.