Abstract:
A plate feeding method includes a suction-holding step for causing suction pads to suck and hold an upper surface adjacent an end edge, remote from nip rollers, of each plate, a moving step, while swinging the suction pads about a moving unit, for moving the moving unit toward the nip rollers, thereby inverting a portion adjacent the end edge of each plate P, and subsequently moving the end edge of the plate inverted to a position to be pinched by the nip rollers, a pinching step for causing the nip rollers to pinch the end edge of the plate having been inverted, a releasing step for canceling suction-holding of the plate by the suction pads, a pressing step for pressing the plate with a support roller, and a transporting step for rotating the nip rollers to transport the plate P.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a plate feeding apparatus for transporting stacked printing plates in order from an uppermost plate, and in an inverted state, to a plate takeout unit such as nip rollers. 
         [0003]    2. Description of the Related Art 
         [0004]    Japanese Unexamined Patent Publication No. 2000-247489, for example, discloses a plate feeding apparatus for transporting printing plates, in an inverted state, to a plate takeout unit. According to this apparatus, a suction point at a leading end of each plate sucked and held by suction pads is moved to coincide with a cycloid formed when a circle having a radius equal to the turning radius of the suction point rolls over the plate surface. Subsequently, the leading end of the plate is pinched by the plate takeout unit. 
         [0005]    Such a plate feeding apparatus that transports printing plates, in an inverted state, to the plate takeout unit has an advantage of transporting the plates reliably without occupying a large floor space even when transporting relatively large plates. 
         [0006]    In such a plate feeding apparatus, plates are usually stacked with end edges aligned by a stopper. Then, with the plate feeding apparatus that transports the plates, in an inverted state, to the plate takeout unit, when a distance from a plate storage unit to the plate takeout unit is small for the size of the plates, the rear end of a plate will thrust itself in between the end edges of the plates stacked and the stopper, making it impossible to transport the plate properly. 
         [0007]    In order to solve this problem, it is conceivable to secure a sufficiently large distance from the plate storage unit to the plate takeout unit in accordance with the size of the plates. However, the increasingly large printing plates used nowadays will result in the entire apparatus occupying a large space. 
       SUMMARY OF THE INVENTION 
       [0008]    The object of this invention, therefore, is to provide a plate feeding apparatus and a plate feeding method which can transport plates reliably without enlarging the apparatus. 
         [0009]    The above object is fulfilled, according to this invention, by a plate feeding apparatus for transporting plates loaded therein, in order from an uppermost plate, while inverting the plates, toward a plate takeout unit that holds and takes out the plate, the apparatus comprising a storage unit for storing a plurality of plates with end edges aligned by a stopper; a moving unit movable along surfaces of the plates stored in the storage unit; a suction unit disposed at a distal end of an arm swingable about the moving unit for sucking and holding an upper surface adjacent an end edge, remote from the plate takeout unit, of each of the plates stored in the storage unit; a moving mechanism for moving the moving unit along the surfaces of the plates stored in the storage unit, from a position remote from the plate takeout unit toward the plate takeout unit, and for swinging the arm about the moving unit, thereby moving the suction unit to invert a portion adjacent the end edge of each plate sucked and held by the suction unit, and subsequently to reach a position for each plate to be held by the plate takeout unit; a pressing member for pressing an inner peripheral surface of a curved portion of each plate which has been curved while being inverted, to locate the curved portion further remote from the plate takeout unit than a vertical line extending from the stopper; and a pressing member moving device for moving the pressing member away from the plate takeout unit. 
         [0010]    Such plate feeding apparatus can transport plates reliably without enlarging the apparatus. 
         [0011]    In a preferred embodiment, the plate feeding apparatus includes a pressing member moving device. Thus, the pressing member can, in a selected position along the surfaces of the plates stored, press a portion of an inner peripheral surface of each plate curved as it is turned back. It is therefore possible to perform properly even when the position of the pressing member pressing plates is changed to handle plates of different sizes. 
         [0012]    In a further aspect of the invention, a plate feeding method is provided for transporting plates stored in a storage unit with end edges of the plates aligned by a stopper, in order from an uppermost plate, while inverting the plates, to nip rollers, the method comprising a suction-holding step for causing a suction unit to suck and hold an upper surface adjacent an end edge, remote from the nip rollers, of each of the plates stored in the storage unit; a moving step, while swinging the suction unit about a moving unit, for moving the moving unit along the surfaces of the plates stored in the storage unit, from a position remote from the nip rollers toward the nip rollers, thereby inverting a portion adjacent the end edge of each plate sucked and held by the suction unit, and subsequently moving the end edge of each plate to a position to be pinched by the nip rollers; a pinching step for causing the nip rollers to pinch the end edge of each plate having been inverted; a releasing step for canceling suction-holding of each plate by the suction unit; and a pressing step for pressing each plate with a pressing member from adjacent the nip rollers to a position further remote from the nip rollers than the stopper. 
         [0013]    Other features and advantages of the invention will be apparent from the following detailed description of the embodiments of the invention. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    For the purpose of illustrating the invention, there are shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangement and instrumentalities shown. 
           [0015]      FIG. 1  is a perspective view of an image recording system having a plate feeding apparatus according to this invention; 
           [0016]      FIG. 2  is a schematic side view of the image recording system having the plate feeding apparatus according to this invention; 
           [0017]      FIG. 3  is a schematic plan view of the image recording system having the plate feeding apparatus according to this invention; 
           [0018]      FIG. 4  is a perspective view of a cassette tray swing mechanism; 
           [0019]      FIG. 5  is a schematic side view of an auto-loader unit; 
           [0020]      FIG. 6  is a schematic side view of the auto-loader unit; 
           [0021]      FIG. 7  is a schematic side view of a moving device and adjacent elements; 
           [0022]      FIG. 8  is a perspective view showing a principal portion of the moving device and adjacent elements; 
           [0023]      FIG. 9  is a schematic view showing the auto-loader unit in an operation to transport a printing plate; 
           [0024]      FIG. 10  is a schematic view showing the auto-loader unit in the operation to transport the printing plate; 
           [0025]      FIG. 11  is a schematic view showing the auto-loader unit in the operation to transport the printing plate; 
           [0026]      FIG. 12  is a schematic view showing the auto-loader unit in the operation to transport the printing plate; 
           [0027]      FIG. 13  is a schematic view showing the auto-loader unit in the operation to transport the printing plate; 
           [0028]      FIG. 14A  is a schematic view showing the auto-loader unit in the operation to transport the printing plate; and 
           [0029]      FIG. 14B  is a schematic view showing the auto-loader unit in the operation to transport the printing plate. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    An embodiment of this invention will be described hereinafter with reference to the drawings.  FIG. 1  is a perspective view of an image recording system having a plate feeding apparatus according to this invention.  FIG. 2  is a schematic side view and  FIG. 3  a schematic plan view of the system. 
         [0031]    This image recording system includes a plate feed unit  2  for use in depositing plates P in each cassette  9  acting as a storage unit, a multi-cassette unit  3  having a plurality of cassettes  9  stacked one over the other, an auto-loader unit  4  for fetching and transporting plates P from a cassette  9  moved to a plate feed position, a plate loading and unloading tray unit  5  having a plate loading tray  131  and a plate unloading tray  132 , a conveyor  8 , an image recorder  6  for recording images on the plates P, and a transport mechanism  7  for transporting the plates P having images recorded thereon in the image recorder  6  to an auto developing device  10  disposed at a downstream stage. 
         [0032]    The above conveyor  8  is provided to transport the plates P from the auto-loader unit  4  to the plate loading and unloading tray unit  5 . In order to facilitate maintenance of the entire apparatus, the conveyor  8  is constructed pivotable upward about one end thereof as shown in two-dot chain lines in  FIG. 2 . 
         [0033]    In this image recording system, the multi-cassette unit  3  accommodates a plurality of cassettes  9  stacked one over the other. When transporting plates P in a cassette  9  to the image recorder  6 , a slide mechanism moves the cassette  9  from the multi-cassette unit  3  to the auto-loader unit  4 . Then, a lift mechanism moves this cassette  9  vertically to the plate feed position shown in  FIG. 2 . 
         [0034]    When storing new plates P in a cassette  9 , the cassette  9  is moved from the multi-cassette unit  3  to the auto-loader unit  4 . Then, this cassette  9  is moved vertically to a cassette fetch position level in which it is aligned horizontally with a cassette holder  11  in a horizontal position shown in solid lines in  FIG. 2 . Subsequently, motors  18  and  19  shown in  FIG. 3  are operated to move the cassette from the auto-loader unit  4  along guide members, not shown, into the cassette holder  11  in the cassette feed unit  2 . 
         [0035]    As shown in  FIG. 4 , this cassette holder  11  is disposed in the plate feed unit  2  to be pivotable about a shaft  12 . The shaft  12  has a spur gear  13  formed peripherally of and coaxially with the shaft  12 . On the other hand, the plate feed unit  2  has a motor  15  with a worm gear  14 . The worm gear  14  is meshed with a worm wheel  17  coaxial with a spur gear  16  meshed with the spur gear  13 . Consequently, the cassette holder  11  is constructed pivotable by the motor  15  between the horizontal position shown in solid lines in  FIG. 2  and a tilted position shown in phantom lines in  FIG. 2 . 
         [0036]    When moving a cassette  9  between the auto-loader unit  4  and cassette holder  11 , the cassette holder  11  is set to the horizontal position. The cassette holder  11  may be horizontal also when storing relatively small plates P in a cassette  9  having moved into the cassette holder  11 . However, when storing relatively large plates P in the cassette  9 , the cassette holder  11  is set to the tilted position. Then the relatively large plates P can be stored in the cassette  9  easily without bending such plates P. 
         [0037]    The auto-loader unit  4  which fetches and transports plates P from inside the above cassette  9  constitutes the plate feeding apparatus according to this invention. The construction of this auto-loader unit  4  will be described hereinafter. 
         [0038]      FIGS. 5 and 6  are schematic side views of the auto-loader unit  4 .  FIG. 5  schematically shows a state before a plate transporting operation, and  FIG. 6  a state after the plate transporting operation. 
         [0039]    This auto-loader unit  4  includes a moving device  200  driven by an endless synchronous belt  61  rotatable by a motor  60 , to run along a guide rail  62 . The moving device  200  is engaged with the synchronous belt  61  through a mobile member  63 . The moving device  200  has an arm  66  swingable relative thereto. The arm  66  has a plurality of suction pads  67  attached to a distal end thereof for sucking and holding a plate P. The arm  66  has a support roller  69  disposed at the distal end thereof for supporting the lower surface of a forward end region of the plate P when transporting the plate P. Further, the arm  66  is connected to an arm  202  having a support roller  71  disposed at a distal end thereof for supporting the lower surface of a central region of the plate P. The arm  66  is driven by a motor  205  described hereinafter, to swing with the arm  202  about the moving device  200 . 
         [0040]    In this auto-loader unit  4 , as the moving device  200  is driven by the motor  60  to move rightward from the position shown in  FIG. 5 , the arm  66  swings about the moving device  200 . Thus, when the moving device  200  is driven by the motor  60  to move rightward, with the suction pads  67  sucking and holding a plate P, the plate P held by the suction pads  67  is first turned back to become inverted as shown in  FIG. 6 . Subsequently, the resulting forward end of the plate P is pinched between a pair of nip rollers  72  and  73  for feeding the plate P toward the conveyor  8 . 
         [0041]    It should be noted that the auto-loader unit  4  has a guard paper discharge mechanism for discharging slip sheet S inserted between the plates P. 
         [0042]      FIG. 7  is a schematic side view of the moving device  200  and adjacent elements.  FIG. 8  is a perspective view showing a principal portion thereof. The mobile member  63  is omitted from  FIG. 7 . 
         [0043]    The arm  66  noted above is connected to a shaft  213  ( FIG. 8 ) included in the moving device  200 , to be swingable about this shaft  213 . The shaft  213  is connected to a shaft  208  through spur gears  212 ,  211 ,  210  and  209 . The shaft  208  is connected to a drive shaft of the motor  205  through spur gears  207  and  206 . Thus, the arm  66  is driven by the motor  205  to swing about the shaft  213 . 
         [0044]    Part of this arm  66  acts as a rack  216 . The rack  216  is meshed with a spur gear  215  mounted on a shaft  214  rotatable by a motor not shown. The arm  66  has a length determined by a rotational position of the spur gear  215 . Thus, the length of the arm  66  is adjustable according to the number of plates P stored in the cassette  9 . 
         [0045]    In this auto-loader unit  4 , as described above, the moving device  200  is driven by the motor  60  to move along the surfaces of the plates P stored in the cassette  9 . In time of this movement, the suction pads  67  arranged at the distal end of the arm  66  are swung about the shaft  213  included in the moving device  200 . 
         [0046]    Next, an operation of the auto-loader unit  4  to transport a plate P will be described.  FIGS. 9 through 14B  are schematic views showing an operation of the auto-loader unit  4  to feed a relatively small plate P. The mobile member  63  is omitted also from  FIGS. 9 through 14B . The plates P stored in the cassette  9  are omitted from  FIGS. 9 through 13 . 
         [0047]    When starting transportation of a plate P, as shown in  FIGS. 5 and 9 , the moving device  200  is moved by the motor  60  to move the suction pads  67  adjacent the end of the plate P remote from the nip rollers  72  and  73 , and cause the suction pads  67  to suck and hold the upper surface of the plate P. At this time, the plates P stored in the cassette  9  are in a state of having end edges adjacent the nip rollers  72  and  73  made even and positioned by a stopper  201 . 
         [0048]    In this state, the moving device  200  is driven by the motor  60  to move toward the nip rollers  72  and  73 . At the same time, the arm  66  is driven by the motor  205  to swing clockwise about the shaft  213 . Consequently, the plate P begins to be turned back as shown in  FIG. 10 . 
         [0049]    The movement of the moving device  200  and the swing of the arm  66  are continued, causing the end edge of the plate P to be pinched between the nip rollers  72  and  73  as shown in  FIG. 11 . Subsequently, the suction holding of the plate P by the suction pads  67  is canceled. 
         [0050]    Next, the moving device  200  is driven by the motor  60  to move away from the nip rollers  72  and  73 . As a result, the support roller  71  disposed at the distal end of the arm  202  contacts a central region of the plate P. In this state, the moving device  200  is moved further away from the nip rollers  72  and  73 . Consequently, as shown in  FIG. 12 , the support roller  71  presses the central region of the plate P to a position on the side of the stopper  201  remote from the nip rollers  72  and  73 . 
         [0051]    That is, the moving device  200  is moved leftward, with the angle of the arm  202  maintained, from the position shown in  FIG. 11  (with the suction pads  67  lying near the nip rollers  72  and  73 ) to the position shown in  FIG. 12 . As a result, the support roller  71  pressing a central region on an inner peripheral surface of a curved portion of the plate P reaches a position on the left side of a vertical line L extending from the stopper  201  (that is, a position on the side of the stopper  201  remote from the nip rollers  72  and  73 ). 
         [0052]    Then, the nip rollers  72  and  73  are rotated to transport the plate P. At this time, as shown in  FIG. 12 , the plate P is guided by the support rollers  69  and  71 . 
         [0053]    The following is the reason for causing the support roller  71  to press the central region of the plate P to the position on the side of the stopper  201  remote from the nip rollers  72  and  73 . 
         [0054]    As the nip rollers  72  and  73  feed the plate P onward, the curved portion of the plate P between the nip rollers  72  and  73  and the stopper  201  gradually becomes short, and its shape gradually changes from curve to straight. However, the above change in shape can be stopped halfway when the plate P, with the central region thereof pressed, is fed by the nip rollers  72  and  73 . It is therefore possible, as shown in  FIGS. 12 and 14A , to raise the uppermost plate P at a predetermined angle α 1  to the rest of the plates P stored. 
         [0055]    On the other hand, when the plate P, without being pressed, is transported by the nip rollers  72  and  73 , as shown in  FIGS. 13 and 14B , the end of the plate P adjacent the stopper  201  will take a vertical position. There occurs a phenomenon, as shown in  FIG. 14B , of the end of the plate P adjacent the stopper  201  thrusting itself in between the end edges of the stacked plates P and the stopper  201 . Such a phenomenon causes a problem that the plate P cannot be transported properly. Such a phenomenon tends to occur where the distance from the stack of plates P to the nip rollers  72  and  73  is small for the size of plates P. 
         [0056]    Therefore, this auto-loader unit  4  is constructed such that, when a plate P is transported by the nip rollers  72  and  73 , the support roller  71  presses the central region of the plate P to a position on the side of the stopper  201  remote from the nip rollers  72  and  73 . 
         [0057]    In the embodiment described above, both of the arm  202  with the support roller  71  acting as the pressing member and the arm  66  with the suction pads  67  are provided for the common moving device  200 . It is therefore impossible for the pressing member to make horizontal movement independently of operation of the suction pads  67 . The pressing member needs to start pressing the plate P after the suction pads  67  release the plate P. 
         [0058]    However, where the pressing member and suction pads  67  can be moved horizontally and separately from each other, it is not necessary to start moving the pressing member horizontally after the nip rollers  72  and  73  pinch the forward end of the plate P. That is, it is possible to start moving the pressing member horizontally while the plate P is being turned back, before the forward end of the plate P is pinched by the nip rollers  72  and  73 . 
         [0059]    This invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention. 
         [0060]    This application claims priority benefit under 35 U.S.C. Section 119 of Japanese Patent Application No. 2006-155591 filed in the Japanese Patent Office on Jun. 5, 2006, the entire disclosure of which is incorporated herein by reference.