Abstract:
Disclosed is a sheet amount indicator for use in a sheet-feeding tray. The sheet-feeding tray includes a sheet stacking part having a base plate where sheets are stacked, and the base plate is configured to rise up for feeding of a topmost sheet stacked. The sheet amount indicator includes a viewing part disposed on an outer surface of the sheet stacking part, an indicator member configured to move as seen through the viewing part, a cooperative mechanism configured to move in accordance with a vertical movement of the base plate, and an amplifying mechanism disposed outside the sheet stacking part and connected to the cooperative mechanism so as to amplify the movement of the cooperative mechanism to transmit the amplified movement to the indicator member.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The disclosure discussed herein generally relates to a sheet amount indicator applicable to a sheet-feeding tray of an image forming apparatus, and an image forming apparatus having such a sheet amount indicator. 
         [0003]    2. Description of the Related Art 
         [0004]    In image forming apparatuses such as copiers, printers, and the like, sheets of paper are generally stored in a stacked fashion in a sheet-feeding tray serving as a paper container. The sheets of paper stored in the sheet-feeding tray are cut in predetermined dimensions and thus have a predetermined size. As illustrated in  FIG. 12 , such a sheet-feeding tray ( 101 ) may be disposed at a lower part of an image forming apparatus  100 . The sheet-feeding tray  101  includes a base plate  102  movable in a vertical direction (i.e., an up-down direction), such that sheets of paper (hereinafter simply called “sheets”)  103  are set in a stacked fashion on the base plate  102 . The base plate  102  is upwardly pressed by a spring  104  toward an upper side so as to allow a top sheet  103  to reach a not-illustrated pickup roller. The sheets are sequentially fed from the top sheet  103  into an image forming part of a main body of the image forming apparatus  100 , thereby forming a desired image on each of the sheets. When the amount of sheets on the sheet-feeding tray is reduced and a small amount of sheets stacked on the sheet-feeding tray, a user may need to physically draw out the sheet-feeding tray from the main body of the image forming apparatus  100  in order to add or supply new sheets to the sheet-feeding tray in a stacked fashion. 
         [0005]    The sheet-feeding tray generally includes a sheet amount indicator configured to indicate presence or absence of sheets, and an amount of sheets. It is possible for a user to check the amount of sheets by directly observing the sheets stacked on the tray while drawing out the sheet-feeding tray; however, in that case, the user may need to draw out the sheet-feeding tray every time the user desires to check the amount of sheets. Hence, printing tasks may be interrupted every time the user wishes to check the amount of sheets, which may degrade printing efficiencies. Moreover, when the image forming apparatus has suddenly stopped due to running out of sheets while performing a large amount of printing, it may be difficult to supply new sheets to the sheet-feeding tray promptly. Accordingly, the user generally supplies sheets to the sheet-feeding tray in advance while monitoring the sheet amount indicator from time to time in order to supply sheets to the sheet-feeding tray and restart the printing tasks promptly. 
         [0006]    There are two types of the sheet amount indicator; a sensor type indicator and a mechanical type indicator. The sensor type sheet amount indicator is configured to detect an amount of sheets by a sensor and indicate the detected amount, whereas the mechanical type sheet amount indicator is configured to mechanically detect the amount of sheets and indicate the detected amount. Since the sensor type sheet amount indicator is expensive, the mechanical type sheet amount indicator is widely used. An example of the mechanical type sheet amount indicator is disclosed in Japanese Laid-open Patent Publication No. 2008-184246 (hereinafter referred to as “Patent Document 1”). In this example, the mechanical type sheet amount indicator  110  may be disposed on a lateral side of the sheet-feeding tray  101  as illustrated in  FIG. 13 . 
         [0007]    The mechanical type sheet amount indicator  110  illustrated in  FIG. 13  includes a first arm  112 , one end of the first arm  112  being supported by a shaft  111  coaxial with a shaft  102   a  of a base plate  102 , the other end of the first arm  112  being connected to a front end of the base plate  102 ; and a second arm  114  rotatable around a shaft  113  disposed on a lateral plate  101   a  of the sheet-feeding tray  101 . One end of the second arm  114  includes an elongated slot  114   a  into which a pin  112   a  of the first arm  112  is inserted. The other end of the second arm  114  extends toward a front side of the sheet-feeding tray  101  in a paper-feeding direction. A projected indicator  114   b  formed on the other end of the second arm  114  is disposed inside a viewing part  120   a  formed in a front cover  120  of the sheet-feeding tray  101  as illustrated in  FIG. 14 . 
         [0008]    When the sheets are loaded in full on the sheet-feeding tray  101 , and the base plate  102  is forced to a lowermost position due to the weight of the loaded sheets as illustrated in  FIG. 14 , a tip of the first arm  112  is located at a lowermost position, and the indicator  114   b  of the second arm  114  is located at an uppermost position. When the loaded sheets run out, the tip  112   b  of the first arm  112  moves up to an uppermost position while the indicator  114   b  moves down to a lowermost position. 
         [0009]    Further, a sheet amount indicator disclosed in Japanese Patent Application Laid-Open Publication No. 6-271141 (hereinafter referred to as “Patent Document 2”) includes a base plate, and a projection part formed on a front end of the base plate. The projection part formed on the front end of the base plate is configured to be engaged with a projection part of a rotatable display member arranged on a front cover of the sheet-feeding tray. In this configuration, the amount of sheets may be indicated when the display member is rotated according to movement of the base plate in a vertical (up-down) direction. 
       RELATED ART DOCUMENT 
     Patent Document 
       [0000]    
       
         Patent Document 1: Japanese Laid-open Patent Publication No. 2008-184246 
         Patent Document 2: Japanese Patent Application Laid-Open Publication No. 6-271141 
       
     
         [0012]    In the mechanical type sheet amount indicator disclosed in Patent Document 1, the first lever and the second lever (i.e., the first and second arms) are disposed on the lateral side of the sheet-feeding tray. Hence, the image forming apparatus may be increased in size according to an increase in the size of the sheet-feeding tray due to a space required for disposing the first and the second levers. Further, flexibility in disposing paper-feeding operating drivers, such as a motor or gears, may be restricted due to the first and the second levers disposed on the lateral side of the sheet-feeding tray. This may further increase the size of the image forming apparatus. 
         [0013]    The mechanical type sheet amount indicator disclosed in Patent Document 2 is not disposed on the lateral side but on the front side. However, a rotational amount of the sheet amount indicator is small between when the sheets are loaded in full (in a full load condition) and when the amount of sheets is small (in a low load condition). 
       SUMMARY OF THE INVENTION 
       [0014]    Accordingly, it is an object of the invention to provide a sheet amount indicator, and an image forming apparatus having the sheet amount indicator capable of reducing in size a main body of the image forming apparatus, and improving the viewability of the sheet amount indicator by effectively disposing the sheet amount indicator inside the image forming apparatus, which may substantially eliminate one or more problems caused by the limitations and disadvantages of the related art. 
         [0015]    According to one embodiment, there is provided a sheet amount indicator for use in a sheet-feeding tray. In the sheet amount indicator, the sheet-feeding tray includes a sheet stacking part having a base plate where sheets are stacked, and the base plate is configured to rise up for feeding of a topmost sheet stacked. The sheet amount indicator includes a viewing part disposed on an outer surface of the sheet stacking part; an indicator member configured to move as seen through the viewing part; a cooperative mechanism configured to move in accordance with a vertical movement of the base plate; and an amplifying mechanism disposed outside the sheet stacking part and connected to the cooperative mechanism so as to amplify the movement of the cooperative mechanism to transmit the amplified movement to the indicator member. 
         [0016]    Additional objects and advantages of the embodiments will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. 
         [0017]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Other objects and further features of embodiments will be apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: 
           [0019]      FIG. 1  is a perspective diagram illustrating an image forming apparatus having a sheet amount indicator according to an embodiment; 
           [0020]      FIG. 2  is an exploded perspective diagram illustrating a sheet-feeding tray; 
           [0021]      FIG. 3  is a perspective diagram illustrating a sheet stacking part; 
           [0022]      FIG. 4  is an enlarged diagram illustrating a main part of a first arm of the sheet stacking part; 
           [0023]      FIG. 5  is a perspective diagram illustrating abase plate and a plate member of the sheet stacking part; 
           [0024]      FIG. 6  is a perspective diagram illustrating a first arm member; 
           [0025]      FIG. 7A  is an exploded perspective diagram illustrating a main part of the sheet-feeding tray; 
           [0026]      FIG. 7B  is a perspective view illustrating the plate member viewing from a rear side; 
           [0027]      FIG. 8A  is a schematic front diagram illustrating the sheet amount indicator when sheets are loaded in full (a full load condition); 
           [0028]      FIG. 8B  is a schematic front diagram illustrating the sheet amount indicator when the amount of sheets is small (a low load condition); 
           [0029]      FIG. 9A  is a schematic front diagram illustrating a sheet amount indicator according to a second embodiment when sheets are in a full load condition; 
           [0030]      FIG. 9B  is a schematic front diagram illustrating the sheet amount indicator according to the second embodiment when sheets are in a low load condition; 
           [0031]      FIG. 10  is a schematic front diagram illustrating a sheet amount indicator according to a third embodiment when sheets are in a full load condition; 
           [0032]      FIG. 11A  is a perspective diagram illustrating an additional sheet-feeding tray having the sheet amount indicator according to the embodiments; 
           [0033]      FIG. 11B  is a perspective diagram illustrating the additional sheet-feeding tray illustrated in  FIG. 11A  from which a driver part is removed; 
           [0034]      FIG. 12  is a schematic side diagram illustrating the sheet-feeding tray disposed at a lower part of a main body of a related-art image forming apparatus; 
           [0035]      FIG. 13  is a perspective diagram illustrating a related-art sheet-feeding tray; and 
           [0036]      FIG. 14  is a side diagram illustrating the related-art sheet amount indicator. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    Preferred embodiments are illustrated below, with reference to the accompanying drawings. 
         [0038]    Note that in the following description, a “sheet-feeding tray” is removably attached to a main body of the image forming apparatus; however, a user is not required to remove the sheet-feeding tray in order to supply or add new sheets. Further, a “paper-feeding cassette” is removably attached to the main body of the image forming apparatus. Note that in the following description, a “paper-feeding cassette” is removably attached to a main body of the apparatus, and a user is required to remove the paper-feeding cassette in order to supply or add new sheets. 
         [0039]    The sheet amount indicator according to embodiments described below may be applicable either to the paper-feeding cassette or the sheet-feeding tray; however, the sheet amount indicator applied to the sheet-feeding tray is illustrated as an example in the description of the embodiments. 
         [0040]      FIG. 1  is a perspective diagram illustrating an image forming apparatus  1  having a sheet amount indicator  10  according to an embodiment. The image forming apparatus  1  includes a main body  1   a,  and a sheet-feeding tray  2  disposed at a lower part of the main body  1   a.  The sheet-feeding tray  2  may be drawn forward (toward a front side of the sheet-feeding tray) in a horizontal direction. A paper-receiving tray  3  is disposed at an upper part of the main body  1   a.    
         [0041]    In the image forming apparatus  1  having the above configuration, a user draws forward the sheet-feeding tray  2  toward the front side of the sheet-feeding tray  2  in a horizontal direction, places sheets of paper in a stacked fashion in the sheet stacking part inside the sheet-feeding tray  2 , and returns the sheet-feeding tray  2  back to the original position so as to initiating a printing task. Each of the sheets inside the sheet-feeding tray  2  is designed to pass through a sheet transferring path of the main body  1   a  of the image forming apparatus  1 , to be transferred to an image forming part where an image is formed on the transferred sheet, and then to be discharged onto the paper-receiving tray  3  after having the image formed on the sheet. A front cover  4  for an internal check is disposed at a front side of the main body  1   a  and at an upper part of the sheet-feeding tray  2 . The front cover  4  may be disposed in this fashion so as to open the cover  4  to handle sheet jamming when the sheet jamming has occurred in the sheet transferring path. 
         [0042]    As illustrated in  FIG. 2 , the sheet-feeding tray  2  has a box-shape. In the sheet-feeding tray  2 , the base plate  2   a  configured to be movable in a vertical (up-down) direction is disposed at a front side of a bottom face of the sheet-feeding tray  2 , and sheets of paper are stored in a stacked fashion on the base plate  2   a.  A locating stopper  2   b  configured to be slidable in a depth (front-rear) direction is disposed at a rear side of the sheet-feeding tray  2 . The locating stopper  2   b  is configured to regulate positional shifts of the sheets stored on the sheet-feeding tray  2  in the depth (front-rear) direction. The locating stopper  2   b  slides along a guide groove  2   c  in the depth (front-rear) direction, and is locked when the sheets on the sheet-feeding tray  2  are aligned by bringing the sheets in contact with the locating stopper  2   b.    
         [0043]    The base plate  2   a  is swingably supported in a vertical (an up-down) direction around a shaft  2   d  that is disposed in a middle of a front-rear direction of the sheet-feeding tray  2 . As illustrated in  FIG. 5 , respective holes  7  through which the shaft  2   d  is passed are formed in left and right sides of the base plate  2   a.  A not-illustrated spring is disposed on a bottom face of the base plate  2   a,  such that the base plate  2   a  is constantly urged by the spring in an upper direction. A paper-feeding mechanism such as a pickup roller or the like is disposed at an upper-front part of the sheet-feeding tray  2 , such that the sheets are sequentially transferred from a top one of the sheets, pass through the sheet transferring path, and reach an image forming part disposed at an upper part of the main body  1   a  inside the image forming apparatus  1 . 
         [0044]    A first arm  11  is disposed at a front-left corner near an outer edge of the sheet-feeding tray  2  as illustrated in  FIGS. 2 to 5 . The first arm  11  has a configuration illustrated in  FIG. 6 . That is, the first arm  11  is configured to serve as an cooperative mechanism that communicates a vertical movement of the base plate  2   a  with later-described second arm  12  and third arm  13 , and to further serve as part of an amplifying mechanism, together with the second arm  12  and the third arm  13 , of the sheet amount indicator  10  according to the embodiment. Note that the vertical movement of the base plate  2   a  may be directly communicated with the second arm  12  by forming a projection on a front end of the base plate  2   a,  and connecting the projection to the second arm  12 . In such a configuration, the projection may serve as the cooperative mechanism. 
         [0045]    As illustrated in  FIG. 3 , the first arm  11  is disposed at a sheet storage outside part located at a front side of the sheet stacking part. That is, the first arm  11  is, as illustrated in  FIGS. 4 and 5 , disposed at a front side of a corner of the base plate  2   a,  and hence, the sheet stacking part has no special restriction by having the first arm  11 . 
         [0046]    The first arm  11  has a middle part that is rotatable in a vertical (an up-down) direction around a fulcrum  15  disposed on the sheet-feeding tray  2  as illustrated in  FIG. 6 . A rear side part  11   a  of the first arm  11  located behind the fulcrum  15  is elongated to be several times as long as a front side part  11   b  of the first arm  11 . The rear side part  11   a  of the first arm  11  includes two angles at respective positions to form a recess in an upper side direction. A rear end  11   c  of the rear side part  11   a  is constantly in forced contact with a right corner of a front end of the bottom face of the base plate  2   a  as illustrated in  FIG. 5 . 
         [0047]    In order to allow the rear end  11   c  of the first arm  11  to be constantly in contact with the base plate  2   a  as described above, a torsion spring or the like is disposed at the fulcrum  15  of the first arm, or a weight is attached to the front side part  11   b  of the first arm  11 , such that the front side part  11   b  of the first arm  11  is heavier than the rear side part  11   a  of the first arm  11 . Further, a pressing part configured to lower the later-described second arm  12  or the third arm  13  in a lower direction is disposed such that the rear end  11   c  of the first arm  11  is constantly in contact with the base plate  2   a.    
         [0048]    Note that the contacting position of the rear end  11   c  may not be limited to the right corner of the front end of the bottom face of the base plate  2   a.  The rear end  11   c  may be in contact with a left corner of the front end of the bottom face of the base plate  2   a,  or may be in contact with any part of the base plate  2   a  insofar as the sheet-feeding tray  2  will not be specially restricted. 
         [0049]    A front edge of the base plate  2   a  approaches the rear side part  11   a  of the first arm  11  as the base plate  2   a  approaches a lowermost position. However, as described above, since the rear side part  11   a  of the first arm  11  is bent to form a recess in an upper side direction, the front edge of the base plate  2   a  will not interfere with the rear side part  11   a  of the first arm  11 . The front side part  11   b  of the first arm  11  extends forward (toward a front side of the first arm) in a relatively short length, and a short cylindrical boss part  11   d  is formed on the front end of the front side part  11   b.    
         [0050]    A front cover  18  having a hand grip  18   a  is configured to be attached to the front face of a main body of the sheet-feeding tray  2  with not-illustrated plural screws, as illustrated in  FIG. 2 . A viewing part  19  formed of an elongated slot elongated in a vertical (an up-down) direction is formed on the left hand side of the front cover  18 . In this embodiment, the viewing part  19  is formed of the elongated slot elongated in the vertical (up-down) direction; however, in view of a design of the front cover  18 , the viewing part  19  may be formed of an elongated slot elongated in a horizontal (left-right) direction or an arc slot. 
         [0051]    A plate member  20  formed of a combination of the second arm  12  and the third arm  13  orthogonal to a longitudinal direction of the first arm  11  is disposed between the front cover  18  and the front end of the main body of the sheet-feeding tray  12 . The plate member  20  is configured to be attached to the front end of the main body of the sheet-feeding tray  2  with three screws inserted through screw holes  20   d  to  20   f  as illustrated with broken lines in  FIG. 7A . The front cover  18  is attached to the main body of the sheet-feeding tray  2  after the plate member  20  has been fixed to the main body of the sheet-feeding tray  2 . 
         [0052]    The second arm  12  and the third arm  13  are disposed on a front face and a rear face of the plate member  20 , respectively, such that the second arm  12  and the third arm  13  are disposed back-to-back via the plate member  20  as illustrated in  FIGS. 7A and 7B . The rear face of the plate member  20  on which the second arm  12  is disposed is directed toward the main body side of the sheet-feeding tray  2 . One end of the second arm  12  is rotatably supported by a fulcrum  20   a  of the plate member  20  as illustrated in  FIG. 7B . A guide groove  12   a  for receiving the boss part  11   d  of the first arm  11  is formed in an area near the fulcrum  20   a  of the second arm  12  as illustrated in  FIGS. 8A and 8B . 
         [0053]    A boss part  13   a  serving as an indicator member inside the viewing part  19  is formed on one end of the third arm  13 . The boss part  13   a  is slidable in a vertical (up-down) direction along the viewing part  19  with movement of the third arm  13 . Further, a boss part  13   b  is formed on the other end of the third arm  13 , and the boss part  13   b  is slidably disposed in a guide groove  20   b  diagonally formed in the plate member  20 . A rotatable supporting part  13   c  disposed in a middle part of the third arm  13  is rotatably connected to an end of the second arm  12 . 
         [0054]    Accordingly, in this embodiment, the second arm  12  and the third arm  13  are disposed along the front cover  18  in a direction orthogonal to the first arm  11  inside the front cover  18  of the sheet-feeding tray  2 . The cover  18  has a sufficient internal space in a horizontal (left-right) direction, such that the second arm  12  and the third arm  13  are arranged in a relatively desired layout together with the viewing part  19  without limitations. 
         [0055]    Accordingly, the moving amount of the boss part  13   a  serving as the indicator member determined by the second arm  12  and the third arm  13 , and the size, shape, and position of the viewing part  19  may be designed in a relatively desired manner without limitations. This may improve the design properties of the front face of the sheet-feeding tray  2 . Further, the sheet stacking part is configured in a compact size by disposing the first to third arms  11  to  13  outside the sheet stacking part as illustrated in  FIG. 3 , which may reduce the size of the main body of the image forming apparatus. 
         [0056]    The sheet amount indicator  10  according to the first embodiment is configured, as described above, such that the base plate  2   a  and the rear end  11   c  of the first arm  11  in contact with the base plate  2   a  are both located at their lowermost positions. On the other hand, the boss part  11   d  of the front end of the first arm  11  is located at its uppermost position, and the second arm  12  and the third arm  13  are located at rising positions as illustrated in  FIG. 8A . Accordingly, the boss part  13   a  of the third arm  13  serving as an indicator member is located at its uppermost position inside the viewing part  19 , indicating that the sheets are loaded in full in the sheet-feeding tray  2 . 
         [0057]    The sheets are reduced in number as printing is performed on more of the sheets. As the number of sheets is reduced, the base plate  2   a  is raised by the spring force, and the rear end  11   c  of the first arm  11  being in contact with the bottom face of the base plate  2   a  is raised as illustrated by dash-dot lines in  FIG. 6 . Accordingly, the boss part  11   d  of the first arm  11  is moved down to a lower side, and the second arm  12  and the third arm  13  are moved down to a lower side as illustrated in  FIG. 8B . Accordingly, the boss part  13   a  of the third arm  13  serving as an indicator member is moved down to a lower side inside the viewing part  19 , indicating that the amount of sheets stacked on the sheet-feeding tray  2  is small (in the low load condition). 
         [0058]    Since the sheet amount indicator  10  includes the amplifying mechanism formed of the first arm  11 , the second arm  12 , and third arm  13 , the moving amount of the base plate  2   a  determined in accordance with the reduction in the amount of sheets may be reflected as a moving amount of the boss part  13   a  serving as the indicator member inside the viewing part  19  by increasing the moving amount of the base plate  2   a  by the first, second, and third arms. Accordingly, viewability of the viewing part  19  may be improved. 
         [0059]    Further, since the second arm  12  and the third arm  13  are disposed along the front cover  18  inside the front cover  18  of the sheet-feeding tray  2 , it is possible to arrange the second arm  12  and the third arm  13  in a desired layout together with the viewing part  19 . In addition, the moving amount of the boss part  13   a  of the third arm  13  serving as an indicator member may be set at a desired magnification by appropriately changing the respective lengths or positions of the second arm  12  and the third arm  13 . Accordingly, the size, the shape, and the position of the sheet amount indicator may be changed according to the desired magnification, which may improve the design properties of the front cover  18  of the sheet stacking part. 
         [0060]    Next, a second embodiment is described with reference to  FIGS. 9A and 9B . 
         [0061]    A sheet amount indicator  10   a  according to the second embodiment excludes the third arm  13  that is provided in the sheet amount indicator  10  according to the first embodiment. In the sheet amount indicator  10   a  according to the second embodiment, a boss part  23  serving as an indicator member disposed at an end of the second arm  12  is configured to indicate an amount of sheets. The boss part  23  is slidably inserted in the viewing part  19  and as well as being slidably inserted in an elongated slot  12   b  formed in the front end of the second arm  12 . 
         [0062]    Since the sheet amount indicator  10   a  according to the second embodiment excludes a widening function of the third arm  13 , the moving amount of the boss part  23  serving as an indicator member is reduced. Accordingly, a length of a viewing part  29  is reduced in a vertical (up-down) direction in an amount provided by the excluded third arm  13 . However, in the sheet-feeding tray  2  of the image forming apparatus having a relatively small capacity to store the sheets, it may be possible to improve the viewability of the amount of sheets via the viewing part  29  having a short length in a vertical (up-down) direction. 
         [0063]    Next, a third embodiment is described with reference to  FIG. 10 . 
         [0064]    A sheet amount indicator  10   b  according to the third embodiment includes a first arm  31  and a second arm  32 . The configuration of the first arm  31  is the same as the configuration of the first arm  11  in the sheet amount indicator  10  according to first embodiment. The second arm  32  has a shape having a curved part in a middle part of the second arm  32 . The curved part of the second arm  32  is rotatably supported by a fulcrum  20   c  provided in the plate member  20 . One end  32   a  of the second arm  32  serving as an indicator member extends inside of the viewing part  32 . The other end  32   b  of the second arm  32  includes an elongated slot  32   c  into which a boss part  31   d  of the front end of the first arm  31  is slidably inserted. 
         [0065]    In the sheet amount indicator  10   b  according to the third embodiment, a boss part  31   d  of a frond end of the first arm  31  is moved up to the uppermost position when the sheets are loaded in full (in the full load condition), and an end  32   a  of the second arm  32  serving as an indicator member is moved to the right end of the viewing part  39 , which indicates that the sheets in the sheet-feeding tray  2  are in the full load condition. Note that the deflection width of the end  32   a  of the second arm  32  is changeable by changing the length of the second arm  32 . Accordingly, the viewability of an amount of sheets viewable from the viewing part  39  may be improved by changing the length of the second arm  32 , or the design properties of the viewing part  39  may be improved based on a desired storage capacity of the paper storage part or desired design properties of the viewing part  39 . 
         [0066]    When the amount of sheets becomes small, the boss part  31   d  of the front end of the first arm  31  is moved down to a lower side as illustrated in dash-dot lines in  FIG. 10 , and the end  32   a  of the second arm  32  serving as an indicator member is moved to the left end inside the viewing part  39 , indicating that the amount of sheets in the sheet-feeding tray  2  is small (in the low load condition). 
         [0067]    The sheet amount indicator according to the embodiments may be applied to an additional tray other than the sheet-feeding tray  2 .  FIGS. 11A and 11B  illustrate an example in which the sheet amount indicator  10  is applied to an additional tray  42 . The additional tray  42  also includes abase plate  42   a,  a stopper  42   b,  a guide groove  42   c,  and a front cover  18  having a hand grip  18   a,  and the viewing part  19  is formed on the left end of the front cover  18 , similar to the example illustrated in  FIG. 2 . Paper-feeding drivers  40  are disposed on a left side and a right side of the additional tray  42 . However, the position of the sheet amount indicator  10  does not overlap the positions of the paper-feeding drivers  40 . Accordingly, the additional tray  42  will not be increased in size by having the additional tray, and no interference may be imposed on flexibility in designing arrangement or layout of the paper-feeding drivers  40 .  FIG. 11B  illustrates the additional tray  42  from which the paper-feeding drivers  40  are removed. 
         [0068]    The embodiments of the present invention are described above; however, the invention is not limited to the above embodiments. Various changes and modification may be made to the above embodiments. For example, in the above embodiments, the viewing part  19 ,  29 , or  39  is disposed on the front cover  18 . However, the viewing part  19 ,  29 , or  39  may be disposed on a lateral face of the main body  1   a  other than the front cover  18 . In addition, in the above embodiments, the viewing part  19 ,  29 , or  39  is applied to the sheet-feeding tray  2 . However, the viewing part  19 ,  29 , or  39  may be applied to a paper-feeding cassette, or the like. Moreover, the amplifying mechanism may be formed of three or more arms. 
         [0069]    According to the above embodiments, since the amplifying mechanism configured to increase a moving width of the base plate of the paper storage part in the vertical (up-down) direction to transmit the increased moving width is disposed outside the paper storage part, the paper storage part does not have any special limitation. Accordingly, the flexibility in designing may be improved without increasing the size of the paper storage part. Further, the amplifying mechanism may be flexibly configured such that the moving amount of the indicator member may be increased. Accordingly, the viewability of the amount of sheets may be improved. 
         [0070]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority or inferiority of the invention. Although the embodiment of the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention. 
         [0071]    This patent application is based on Japanese Priority Patent Application No. 2011-279667 filed on Dec. 21, 2011, the entire contents of which are hereby incorporated herein by reference.