Patent Publication Number: US-2011074095-A1

Title: Sheet conveying apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application continuation of U.S. patent application Ser. No. 12/207,400, filed Sep. 9, 2008, which is based upon and claims the benefit of priority from prior Applications No. 60/972,236, filed Sep. 13, 2007, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a sheet conveying apparatus that has a sheet cassette in which sheet bundles to be fed can be horizontally stacked side by side. 
     BACKGROUND 
     Conventionally, there is a tandem large capacity feeder (hereinafter referred to as tandem LCF) as one of large capacity paper feeding apparatuses in which sheet bundles to be fed can be horizontally stacked side by side. The tandem LCF has the structure including, in the inside of one paper feeding apparatus, two trays that store two sheet bundles. 
     In the tandem LCF, paper feeding mechanisms that respectively discharge sheets to trays on which sheet bundles are stacked in the inside of a paper feeding apparatus are provided. In the tandem LCF having such plural paper feeding mechanisms, there are problems of an increase in size of the paper feeding apparatus, a decrease in a stacking amount of sheet bundles stored in the paper feeding apparatus, and manufacturing cost. 
     Another tandem LCF in the past has the structure in which a paper feeding mechanism is provided for only one of trays on which a sheet bundle is stacked. As shown in  FIGS. 27 to 30 , in such a tandem LCF, when a sheet bundle stacked on a first tray  901  for which the paper feeding mechanism is exhausted, a sheet bundle P stacked on a second tray  902  is transferred to the first tray  901 . 
     However, when the sheet bundle P stacked on the second tray  902  is transferred to the first tray  901  provided in the paper feeding mechanism, as shown in  FIG. 28 , the second tray  902  is moved to a position above the first tray  901 . The second tray  902  on which the sheet bundle P is stacked is once lowered after the second tray  902  reaches the first tray  901  as shown in  FIG. 29 . As shown in  FIG. 30 , the second tray  902  returns to an original predetermined position after the sheet bundle P is transferred to the first tray  901 . 
     Therefore, a configuration of the tandem LCF is complicated. In order to realize such a configuration, the tandem LCF requires spaces in both a height direction and a horizontal direction. Since a large number of sheets are stacked on the second tray  902 , the second tray is required not to hang down because of the weight of the sheet bundle P. Therefore, rollers are arranged on a lower surface of the second tray  902 . The second tray  902  moves to the first tray  901  side along a rail. The second tray  902  lowers the sheet bundle P in order to transfer the sheet bundle P to the first tray  901 . In lowering the sheet bundle P, since the rollers are obstacles, it is necessary to permit the rollers to escape. Therefore, such a tandem LCF has problems in terms of cost and spaces. 
     In order to prevent the second tray  902  to hang down, even when the second tray  902  and a holding section are firmly fixed, the problems in cost and spaces are inevitable. 
     Therefore, the present invention provides a sheet conveying apparatus that can smoothly transfer a sheet bundle in the tandem LCF. 
     SUMMARY 
     According to one aspect of the present invention, there is provided a sheet conveying apparatus including a first storing unit in which a sheet bundle is stacked, a second storing unit that is provided near the first storing unit and in which the sheet bundle is stacked, a transfer tray that is provided in the second storing unit and transfers the sheet bundle from the second storing unit to the first storing unit, and a stopper that regulates, when the transfer tray transfers the stacked sheet bundle from the second storing unit to the first storing unit and moves from the first storing unit to the second storing unit, movement of the sheet bundle on the transfer tray. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing an external appearance of an image forming apparatus according to an embodiment; 
         FIG. 2  is a perspective view showing the structure of a tandem LCF according to the embodiment; 
         FIG. 3  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 4  is a perspective view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 5  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 6  is a perspective view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 7  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 8  is a perspective view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 9  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 10  is a perspective view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 11  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 12  is a perspective view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 13  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 14  is a perspective view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 15  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 16  is a perspective view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 17  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 18  is a perspective view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 19  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 20  is a perspective view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 21  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 22  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 23  is a side view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 24  is a side view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 25  is a top view showing the structure of the tandem LCF according to the embodiment; 
         FIG. 26  is a block diagram showing a control system of the image forming apparatus according to the embodiment; 
         FIG. 27  is a diagram showing the structure of a tandem LCF in the past; 
         FIG. 28  is a diagram showing the structure of the tandem LCF in the past; 
         FIG. 29  is a diagram showing the structure of the tandem LCF in the past; and 
         FIG. 30  is a diagram showing the structure of the tandem LCF in the past. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment is explained below. 
       FIG. 1  is a perspective view showing an external appearance of an image forming apparatus  1  according to an embodiment. The image forming apparatus  1  includes an image forming unit  10  for outputting image information as an output image called, for example, a hard copy or a printout, a sheet feeding unit  20  that can feed a sheet (an output medium) of an arbitrary size used for image output to the image forming unit  10 , and a scanner that captures, as image data, image information, which is an object of image formation, from an object that keeps the image information (hereinafter referred to as original). An automatic document feeder  30  that discharges, when the original is sheet-like, after scanning of the image information in the scanner is finished, the original for which the scanning is finished from a scanning position to a discharge position and guides the next original to the scanning position is provided above the image forming unit  10 . An instruction input unit for instructing the start of image formation in the image forming unit  10  and the start for scanning of image information of an original by the scanner  50 , i.e., a control panel  40 , is provided in the image forming apparatus  1 . 
     A paper discharge tray  60  that discharges a sheet on which an image is printed by the image forming unit  10  is provided on a side of the image forming apparatus  1 . A first opening and closing member  70  and a second opening and closing member  80  are provided on a side on the opposite side of the side on which the paper discharge tray  60  is provided. 
     The first opening and closing member  70  is a sheet conveying unit provided to be connected to the image forming unit  10 . The second opening and closing member  80  is a sheet manual feed unit provided to come into contact with the first opening and closing member  70 . A block diagram showing a control system of the image forming apparatus  1  according to this embodiment is shown in  FIG. 26 . A control device  2  includes a CPU  3 , a ROM  4 , and a RAM  5 . The CPU  3  controls respective sensors and respective motors on the basis of control information recorded in the ROM  4  in advance. The RAM  5  temporarily records necessary information. 
       FIG. 2  is a perspective view showing the structure of a tandem LCF  20  applied as the sheet feeding unit  20  shown in  FIG. 1  according to this embodiment. An arrow A indicates a direction in which the tandem LCF  20  is inserted in and drawn out from the image forming apparatus  1 .  FIG. 3  is a top view showing the structure of the tandem LCF  20 .  FIGS. 2 and 3  show a state in which the tandem LCF  20  in which the sheet bundle P is not stacked is drawn out from the image forming apparatus  1 . 
     The tandem LCF  20  includes a first storing unit  100  and a second storing unit  200  provided near the first storing unit  100  as one body. The sheet bundle P fed to the image forming unit  10  is stacked in the first storing unit  100 . The first storing unit  100  is a paper feeding side in which a paper feeding roller  300  is provided as a paper feeding member that feeds sheets one by one from the top of the sheet bundle P. The CPU  3  drives, on the basis of an input for print processing by a user, the paper feeding roller  300  using a paper feeding roller driving motor  310  and feeds paper to the image forming unit  10 . The first storing unit  100  includes a paper feeding side tray  101 . The CPU  3  drives a paper feeding side tray driving motor  311  according to a decrease in the number of sheets P stacked on the paper feeding side tray  101  and moves the paper feeding side tray  101  upward to a position in contact with the paper feeding roller  300  in order to press the sheet bundle P against the paper feeding roller  300 . 
     The sheet bundle P transferred to the first storing unit  100  when all the sheets of the sheet bundle P stacked in the first storing unit  100  are fed by the paper feeding roller  300  are stacked in the second storing unit  200 . The second storing unit  200  is a waiting side including a transfer tray  201  that transfers the sheet bundle P to the first storing unit  100  when all the sheets of the sheet bundle P stacked in the first storing unit  100  are fed by the paper feeding roller  300 . The user can draw out the first storing unit  100  and the second storing unit  200  from the image forming apparatus  1  independently from each other and supply the sheet bundle P therein. 
     In the tandem LCF  20 , a guide member  301  is provided on a side between the first storing unit  100  and the second storing unit  200 , i.e., between the paper feeding side and the waiting side. The guide member  301  is a member for correctly setting the sheet bundle P in the second storing unit  200  using a first stopper  302  and a second stopper  303 . 
     Further, in the tandem LCF  20 , the first stopper  302  and the second stopper  303  are provided on the side between the first storing unit  100  and the second storing unit  200 , i.e., between the paper feeding side and the waiting side. The first stopper  302  and the second stopper  303  play a role for correctly setting the sheet bundle P in the first storing unit  100 . The user can correctly set the sheet bundle P in predetermined positions of the first storing unit  100  and the second storing unit  200 . 
     The first stopper  302  and the second stopper  303  move from two places opposed to each other to the center in a direction orthogonal to a transfer direction of the sheet bundle P to divide the first storing unit  100  and the second storing unit  200 . After the transfer tray  201  transfers the sheet bundle P to the paper feeding side tray  101 , the first stopper  302  and the second stopper  303  regulate movement of the sheet bundle P not to return to the second storing unit  200  in a state in which the sheet bundle P is stacked on the transfer tray  201 . 
       FIG. 4  is a perspective view showing the structure of the tandem LCF  20  in which the sheet bundles P are stacked in the first storing unit  100  and the second storing unit  200 , respectively.  FIG. 5  is a top view showing the structure of the tandem LCF  20  shown in  FIG. 4 . The tandem LCF  20  is drawn out from the image forming apparatus  1 . The user can stack the sheet bundles P on the first storing unit  100  and the second storing unit  200 , respectively. The sheet bundle P is stacked on the paper feeding tray  101  in the first storing unit  100 . The sheet bundle P is stacked on the paper feeding tray  201  in the second storing unit  200 . 
       FIG. 6  is a perspective view showing the structure of the tandem LCF  20  inserted in the image forming apparatus  1  from the state shown in  FIGS. 4 and 5  in which the sheet bundles P are stacked in the first storing unit  100  and the second storing unit  200 .  FIG. 7  is a top view showing the structure of the tandem LCF  20  shown in  FIG. 6 . 
     When the tandem LCF  20  is inserted into the image forming unit  1 , the CPU  3  detects the insertion of the tandem LCF  20  into the image forming apparatus  1  using an open and close sensor  304  provided in a predetermined position of the image forming apparatus  1 . The CPU  3  drives a guide member driving motor  305  to move, to prevent the guide member  301  from impeding the transfer of the sheet bundle P, the guide member  301  to a position where the guide member  301  is opposed to no portion of the sheet bundle P in a direction from the first storing unit  100  to the second storing unit  200 . 
       FIG. 8  is a perspective view showing the structure of the tandem LCF  20  in a state in which all the sheets of the sheet bundle P stacked in the first storing unit  100  are fed by the paper feeding roller  300  from the state shown in  FIGS. 6 and 7  and the sheet bundle P is stacked only in the second storing unit  200 .  FIG. 9  is a top view showing the structure of the tandem LCF  20  in the state shown in  FIG. 8 . 
       FIG. 10  is a perspective view showing the structure of the tandem LCF  20  in a state in which the first stopper  302  and the second stopper  303  move in the state shown in  FIGS. 8 and 9 .  FIG. 11  is a top view showing the structure of the tandem LCF  20  shown in  FIG. 10 . 
     When it is determined by a sheet detection sensor  306 , which is arranged in a predetermined position of the first storing unit  100 , that all the sheets P stacked in the first storing unit  100  are fed, the CPU  3  drives a stopper driving motor  307  to move the first stopper  302  and the second stopper  303  to a position where the first stopper  302  and the second stopper  303  are opposed to no portion of the sheet bundle P. 
       FIG. 12  is a perspective view showing the structure of the tandem LCF  20  in a state in which the transfer tray  201  starts to transfer the sheet bundle P stacked in the second storing unit  200  to the first storing unit  100  from the state shown in  FIGS. 10 and 11 .  FIG. 13  is a top view showing the structure of the tandem LCF  20  shown in  FIG. 12 . 
     When it is determined that the movement of the first stopper  302  and the second stopper  303  is completed, the CPU  3  drives a transfer tray driving motor  308  to start transfer of the sheet bundle P by the transfer tray  201 . 
     The transfer tray  201  includes a trailing end guide member  202  in a direction from the second storing unit  200  to the first storing unit  100 . The trailing end guide member  202  comes into contact with a side of a trailing end of the sheet bundle P in a transfer direction of the transfer tray  201 . When the transfer tray  201  moves from the second storing unit  200  to the first storing unit  100 , the sheet bundle P is moved from the second storing unit  200  to the first storing unit  100  by the transfer tray  201  with a shape thereof kept by the trailing end guide member  202 . 
       FIG. 14  is a perspective view showing the structure of the tandem LCF  20  in a state in which the transfer tray  201  completes the transfer of the sheet bundle P to the first storing unit  100  from the state show in  FIGS. 12 and 13 .  FIG. 15  is a top view showing the structure of the tandem LCF  20  shown in  FIG. 14 . 
     The transfer of the sheet bundle P is finished when the transfer tray  201  transfers the sheet bundle P to the predetermined position of the first storing unit  100 . 
       FIG. 16  is a perspective view showing the structure of the tandem LCF  20  in a state in which the first stopper  302  and the second stopper  303  move in the state shown in  FIGS. 14 and 15 .  FIG. 17  is a top view showing the structure of the tandem LCF  20  shown in  FIG. 16 . 
     When it is determined that the transfer tray  201  completes the transfer of the sheet bundle P to the first storing unit  100 , the CPU  3  drives the stopper driving motor  307  to move the first stopper  302  and the second stopper  303  to positions where parts of the first stopper  302  and the second stopper  303  are opposed to the sheets P. The first stopper  302  and the second stopper  303  are inserted between the trailing end guide member  202  and the trailing end of the sheet bundle P. 
       FIG. 18  is a perspective view showing the structure of the tandem LCF  20  in a state in which the transfer tray  201  returns from the first storing unit  100  to the second storing unit  200  in the state shown in  FIGS. 16 and 17 .  FIG. 19  is a top view showing the structure of the tandem LCF  20  shown in  FIG. 18 . 
     When it is determined that the movement of the first stopper  302  and the second stopper  303  is completed, the CPU  3  drives the transfer tray driving motor  308  to move the transfer tray  201  from the first storing unit  100  to the second storing unit  200 . 
       FIG. 20  is a perspective view showing the structure of the tandem LCF  20  in a state in which the transfer tray  102  completely moves from the first storing unit  100  to the second storing unit  200  in the state shown in  FIGS. 18 and 19 .  FIG. 21  is a top view showing the structure of the tandem LCF  20  shown in  FIG. 20 . 
     When the transfer tray  201  moves from the first storing unit  100  to the second storing unit  200 , the first stopper  302  and the second stopper  303  holds the sheet bundle P from both ends thereof to prevent all the sheets of the sheet bundle P from moving following the transfer tray  201 . 
     In other words, the first stopper  302  and the second stopper  303  set upper ends thereof at the height equal to or larger than the maximum height of the sheet bundle P that can be stacked on the transfer tray  201  and set lower ends thereof in a position just in contact with a sheet at the bottom of the sheet bundle P stacked on the transfer tray  201 . Therefore, the sheet bundle P is completely prevented from moving from the first storing unit  100  to the second storing unit  200  by the first stopper  302  and the second stopper  303 . The lower ends of the first stopper  302  and the second stopper  303  may be lower than the position of the bottom of the sheet bundle P. 
     When the transfer tray  201  moves from the first storing unit  100  to the second storing unit  200 , in order to regulate the movement of the sheet bundle P, the height of the upper ends of the first stopper  302  and the second stopper  303  may be lower than the maximum height of the sheet bundle P that can be stacked. This makes use of the principle that, since the transfer tray  201  at the bottom of the sheet bundle P is drawn out, if a lower side of the sheet bundle P does not move, an upper side of the sheet bundle P does not move either. 
     Dimensions of the transfer tray  201  and the paper feeding side tray  101  configuring the tandem LCF  20  are explained with reference to  FIG. 22 .  FIG. 22  is a top view showing the structure of the tandem LCF  20 . The transfer tray  201  is located in the predetermined position of the second storing unit  200 . A distance L 1  is a distance in the transfer direction of the transfer tray  201  between the trailing end guide member  202  of the transfer tray  201  and the guide member  301  opposed to the trailing end guide member  202 . A distance L 2  is a distance in the transfer direction of the transfer tray  201  from the first stopper  302  and the second stopper  303  to a surface in contact with a side of the sheet bundle P in the first storing unit  100 . The tandem LCF  20  is designed to satisfy a relation L 1 &lt;L 2 . 
     The tandem LCF  20  not including the guide member  301  is explained. When the user stacks the sheet bundle P in the first storing unit  100  and the second storing unit  200 , the user can freely stack the sheet bundle P on the transfer tray  201 . When the sheets P are viewed from a side as shown in  FIG. 23 , the sheets P are stacked in a zigzag along the transfer direction. When the transfer tray  201  transfers the sheets P stacked in such a state, a trailing end of the sheet bundle P along the transfer direction comes into contact with an end face of the first storing unit  100 . Frictional force is generated in boundaries of the sheets of the sheet bundle P. A load is imposed on the driving along the transfer direction of the transfer tray  21 . Therefore, the transfer tray  201  may not be able to completely transfer the sheet bundle P to the predetermined position of the first storing unit  100 . 
     As shown in  FIGS. 16 and 17 , when parts of the first stopper  302  and the second stopper  303  move to the positions opposed to the sheet bundle P, respectively, the first stopper  302  and the second stopper  303  is obstructed by the sheet bundle P and cannot move to positions opposed to the side of the sheet bundle P. Therefore, when the transfer tray  201  moves from the first storing unit  100  to the predetermined position of the second storing unit  200 , the first stopper  302  and the second stopper  303  do not act on the sheet bundle P. In other words, the entire the sheet bundle P or a part of the sheet bundle P returns to the second storing unit  200  following the movement of the transfer tray  201  from the first storing unit  100  to the second storing unit  200 . 
     In this embodiment, as shown in  FIG. 22 , the tandem LCF  20  is designed such that the distance L 1  and the distance L 2  satisfy the relation L 1 &lt;L 2 . Therefore, when the user stacks the sheet bundle P in the second storing unit  200 , an amount of fluctuation in a zigzag in the moving direction of the sheet bundle P is equal to or smaller than the distance L 1 . Therefore, even when the transfer tray  201  transfers the sheet bundle P to the first storing unit  100 , since the distance L 2  is larger than the distance L 1 , the transfer tray  201  can surely transfer the sheet bundle P to the predetermined position of the first storing unit  100 . Therefore, the first stopper  302  and the second stopper  303  can be inserted in the positions opposed to the side of the sheet bundle P without being obstructed by the sheet bundle P. Consequently, the first stopper  302  and the second stopper  303  can hold the sheet bundle P from both the ends thereof to prevent the sheet bundle P from returning to the second storing unit  200  following the movement of the transfer tray  201 . 
     In this embodiment, as shown in  FIG. 25 , rollers  203  that prevent the transfer tray  201  from hanging down are arranged below the transfer tray  201 , i.e., between the transfer tray  201  and the first storing unit  100 . The transfer tray  201  is guided to the first storing unit  100  by the rollers  203  on grooves provided in the first storing unit  100  and the second storing unit  200 . The sheet bundle P stacked on the transfer tray  201  is surely transferred to the first storing unit  100  by the first stopper  302  and the second stopper  303 . The sheet bundle P does not fall from the transfer tray  201  to the paper feeding side tray  101  at a time. Therefore, in the tandem LCF  20 , it is unnecessary to provide a complicated mechanism for permitting the rollers  203  to escape from the transfer tray  201  and firmly build the transfer tray  201  and a holding section for the transfer tray  201 . The tandem LCF  20  according to this embodiment is inexpensive and space-saving compared with the tandem LCF in the past and does not cause a sheet transfer failure.