Patent Publication Number: US-7222846-B2

Title: Sheet take-out apparatus and method of taking out sheets

Description:
FIELD OF THE INVENTION 
   This invention generally relates to a sheet take-out apparatus and a method of taking out sheets, and, more particularly, to a sheet take-out apparatus and a method that successively takes out one sheet at a time from a bundle of stacked sheets. 
   This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2003-168123, filed on Jun. 12, 2003, the entire contents of which are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   In general, a sheet-handling device that carries out predetermined treatments is required to securely take out one sheet at a time from a bundle of stacked sheets. In compliance with the requirement a prior art sheet-handling device proposed up to now is provided with a take-out apparatus to prevent taking-out two sheets or more, i.e., a multi-sheet take-out prevention apparatus disclosed in Japanese Unexamined Patent Applications Tokkaihei 8-151135, Tokkaihei 9-110207, Tokkaihei 10-101239, Tokkaihei 10-250881. 
   Briefly, the sheet take-out apparatus disclosed in the Japanese Unexamined Patent Applications is provided with an air spout unit to spout air to a bundle of sheets, a take-out unit to suck a forward edge portion of a sheet and take it out from the bundle of sheets, and a depression unit disposed in the vicinity of the take-out unit to depress another forward edge portion of the sheets against the take-out unit. The sheet take-out apparatus particularly in Japanese Unexamined Patent Application Tokkaihei 10-101239 detects accompanied sheets or sheet conditions and feeds such detected information back to a controller in a take-out unit to achieve the optimum sheet take-out condition by controlling the following: depressing force of a voice coil motor, displacement of a movable sheet-feeding member of a sheet-feeding member, sucking force of a chamber block, or an actuator to adjust a position of an air nozzle. 
   As set forth above, the sheet take-out apparatus disclosed in the Japanese Unexamined Patent Applications proves to be difficult in taking out only one sheet at a time from the bundle of sheets primarily because the depression unit depresses the forward edge portion of the sheets against the take-out unit so that sheets at the take-out position are not always easily separate from each other. In addition, however, since sheets may be crushed immediately under a sheet take-out rotor in the take-out apparatus disclosed in Japanese Unexamined Patent Application Tokkaihei 10-101239, air is not supplied there. This leads to large friction among the sheets so that multi-sheet take-out troubles arise easily. In the case that changes in friction coefficients depend on sheet surface conditions, the sheet take-out apparatus is readily subject to their influence and its robustness becomes low. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention is for solving the problem set forth above and provides a sheet take-out apparatus and a method that, regardless of sheet surface conditions, is capable of securely preventing the taking out of a plurality of sheets at a time. 
   One aspect of the present invention is directed to a sheet take-out apparatus provided with a sheet-feeding member on which a bundle of sheets is placed, an air spout unit that spouts out air toward a side of the sheets depressed by said depression member, a sheet take-out unit to take out a sheet from the bundle of sheets toward which the air spout unit spouts the air, and a depression member that depresses the sheets against the sheet-feeding member on a rear edge side located behind a central potion of the sheets with respect to a taking-out direction of the take-out unit. 
   Another aspect of the present invention is directed to a method of taking out a sheet including placing a bundle of sheets on a sheet-feeding member, spouting out air toward a side of the depressed sheets, taking out a sheet from the sheets toward which the air is spouted, and depressing the sheets against the sheet-feeding member on a rear edge side located behind a central potion of the sheets with respect to a taking-out direction of the take-out unit. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the present invention and many of its attendant advantages will be readily obtained as the same becomes better understood by reference to the following detailed descriptions when considered in connection with the accompanying drawings, wherein: 
       FIG. 1  is a schematic structure diagram of a sheet-handling system to which an embodiment of the present invention is applied; 
       FIG. 2  is a schematic side view of an embodiment of a sheet take-out apparatus according to the present invention; 
       FIG. 3  is a schematic perspective view of the sheet take-out apparatus shown in  FIG. 2 ; 
       FIG. 4  is a schematic perspective view of a sheet-feeding member and a guide plate shown in  FIG. 2 ; 
       FIG. 5  is a schematic cross-sectional view of a reverse-rotation rotor shown in  FIG. 2 ; 
       FIGS. 6–8  show schematic take-out operations of the sheet take-out apparatus shown in  FIG. 2 ; 
       FIG. 9  is a schematic side view of a sheet take-out apparatus according to another embodiment of the present invention; and 
       FIG. 10  is a schematic perspective view of the sheet take-out apparatus shown in  FIG. 9 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiments of the present invention will be explained below with reference to the attached drawings. It should be noted that the present invention is not limited to the embodiments but covers their equivalents. Throughout the attached drawings, similar or same reference numerals show similar, equivalent or same components. The drawings, however, are shown schematically for the purpose of explanation so that their components are not necessarily the same in shape or dimension as actual ones. In other words, concrete shapes or dimensions of the components should be considered as described in these specifications, not in view of the ones shown in the drawings. Further, some components shown in the drawings may be different in dimension or ratio from each other. 
   A sheet take-out apparatus and a method of taking out sheets of the first embodiment of the present invention will be explained below with reference to the attached drawings. 
   First, with reference to  FIG. 1  an explanation will be provided for sheet-handling system  1  to which the present invention is applied. Sheet-handling system  1  successively takes out sheets from a bundle of stacked sheets and conveys them for further treatments, such as examination and classification of the sheets into usable and discard ones. By way of example, the sheet-handling rate of sheet-handling system  1  is tens of sheets per second while the conveying speed is several meters per second. The rate and speed are always constant. 
   As shown in  FIG. 1 , sheet-handling system  1  is provided with sheet take-out apparatus  2 , conveyor  3 , processing unit  4 , separator  5 , and the first and second stackers  6  and  7 . Sheet take-out apparatus  2  successively takes out one sheet P at a time at a predetermined rate. Conveyor  3  coveys sheet P taken out by sheet take-out apparatus  2  in a predetermined direction. Processing unit  4  carries out a predetermined treatment for sheet P. In response to treatment information supplied from processing unit  4  separator  5  sends sheet P to either the first or second stacker  6  or  7  where sheet P is collected. 
   As will be set forth later in detail, sheet take-out apparatus  2  takes out one sheet P at a time from the upper portion of a bundle of “n” stacked sheets (n: an arbitrary integer). Sheet take-out apparatus  2  delivers the sheet P to conveyor  3 , which conveys the same held by its conveying belts at a constant speed. 
   Processing unit  4  is disposed to face conveying path  9  in front of sheet take-out apparatus  2 . Processing unit  4  examines the surface of sheet P taken out by sheet take-out apparatus  2  to check how much it is torn or how dirty it is. Consequently, processing unit  4  determines in light of results of such checking whether sheet P is still usable or must be discarded. 
   Separator  5  has the first gate  14 A that sends sheets in conveying direction A or B in response to processing information supplied from processing unit  4  and the second gate  14 B that sends sheets in conveying direction C or D in accordance with a predetermined number of conveyed sheets. 
   More particularly, the first gate  14 A guides the sheets selected to be discarded in response to the processing information to the second stacker  7  through the first conveying branch  10 . The first gate  14 A also guides those determined to be still usable in response to the processing information to the first stacker  6  through the second conveying branch  11 . 
   The second gate  14 B, on the other hand, conveys the predetermined number of the sheets to the first stacker unit  6   a  of the first stacker  6  through the third conveying branch  12 . The second gate  14 B also conveys the predetermined number of the sheets to the second stacker unit  6   b  of the first stacker  6  through the fourth conveying branch  13 . 
   The first stacker  6  has the first and second stacker units  6   a  and  6   b  provided with the first and second stacker wheels  16 A and  16 B, respectively. Stacker wheels  16 A and  16 B each consist of discs provided with curved grooves equally disposed around the center and stepping motors. Stacker wheels  16 A and  16 B are driven by the stepping motors, receive high-speed conveying sheets P and put them into the first and second stacker units  6   a  and  6   b  where bundles of sheets P are stacked again, respectively. 
   Passing number of sheets P conveyed to the first stacker  6  is counted by optical sensor  18  provided opposite to the second conveying branch  11 . Whenever the number of sheets P is counted to a predetermined one, e.g., 100, the second gate  14 B is turned to alternatively stack 100 sheets at the first stacker unit  6   a  or the second stacker unit  6   b.    
   The second stacker  7  receives conveying sheets P to stack a bundle of sheets P again. The sheets stacked are then cut out by a shredder for discarding. 
   The structure of sheet take-out apparatus  2  will be described with reference to  FIGS. 2–4 . 
   Sheet take-out apparatus  2  primarily consists of sheet feeder  20 , depression unit  27 , air spout unit  26  and take-out unit  30 . 
   Sheet feeder  20  is provided with sheet-feeding member  22 , movable sheet-feeding member  21  and upper surface position detection lever  23 . A bundle of sheets are stacked on sheet-feeding member  22 . Movable sheet-feeding member  21  is used to move sheet-feeding member  22  in a direction (e.g., an up and down direction) in parallel with the stacking direction of sheets P. Upper surface position detection lever  23  is a position sensor that detects the upper surface position (i.e., the top surface position) of the bundle of sheets stacked on sheet-feeding member  22 . Upper surface position detection lever  23  converts the upper surface position into an electric signal and sends it to a controller not shown in the drawings. The controller controls movable sheet-feeding member  21  in response to the electric signal to move sheet-feeding member  22  so that it sets the top surface of sheets P to a fixed position in the vicinity of take-out unit  30 . 
   Sheet feeder  20  is provided with front edge guide plate  24  fixed at the front portion of sheet-feeding member  22  on the front edge side along the longitudinal or taking-out direction of the stacked sheets. Front edge guide plate  24  performs to line up the front edge of sheets P and to adjust the posture of sheet P by guiding its lower side when take-out unit  30  delivers sheet P to conveyor  3 . 
   Sheet feeder  20  is also equipped with rear edge guide plate  28  provided at the rear portion of sheet-feeding member  22 , i.e., the rear edge side along the longitudinal or taking-out direction of the stacked sheets. Rear edge guide plate  28 , which is movable along the longitudinal or taking-out direction of sheets P placed on sheet-feeding member  22  to adjust its own position depending on lengths of sheets P, controls a position of sheets P on the rear edge side. 
   Sheet feeder  20  further includes both-side guide plates  29  provided at both sides of sheet-feeding member  22  to guide the width of a bundle of sheets. Sheet-feeding member  22  consists of rod members  22 A that are in parallel with each other and arranged to be on the same plane. Both-side guide plates  29  each are provided with slits  29 S in which rod members  22 A are movably held, respectively. The width of slit  29 S is approximately the same as the diameter of rod member  22 A while slit  29 S is long in direction Y and rounded at both ends. 
   When rod members  22 A of sheet-feeding member  22  are moved by movable sheet-feeding member  21 , rod members  22 A move along slits  29 S in direction Y, i.e., in the sheet-stacking direction. Both-side guide plates  29  are movable in accordance with the width of a bundle of sheets in direction X while rod members  22 A are kept engaged with slits  29 S. 
   Depression unit  27  depresses a bundle of sheets against sheet-feeding member  22 . Thus, depression unit  27  is provided with air nozzle  27 A that spouts out air toward sheet-feeding member  22 . Air nozzle  27 A is fixed to face sheet-feeding member  22  so that it spouts out air to depresses the top one of stacked sheets P placed on the sheet-feeding member  22 . 
   Air nozzle  27 A is preferably disposed at a rear position from the center of a bundle of sheets stacked on sheet-feeding member  22 . In the case that the stacked sheets are 120 mm through 170 mm long and 60 mm through 90 mm wide, the position toward which air nozzle  27 A is directed is far by about 60 mm through about 85 mm or farther from the front edge of stacked sheets P and an air depression pressure against the sheet is set to 10 kPa through 15 kPa. 
   Air spout unit  26  also spouts out air to the front end side in the taking-out direction of the stacked sheets depressed by depression unit  27 . Air spout unit  26  is provided with at least one of the first and second air nozzles  26 A and  26 B set in the vicinity of take-out unit  30 . 
   In this embodiment, the first and second air nozzles  26 A and  26 B are disposed on both sides of the sheets stacked on sheet-feeding member  22 , respectively. The first and second air nozzles  26 A and  26 B are fixed at both-side guide plates  29  and spout air at a pressure of 10 kPa through 15 kPa. 
   Thus, edge portions of the first and second air nozzles  26 A and  26 B are set to be movable as both-side guide plates  29  move to line up both edges of the sheets. With this structure, therefore, a gap defined between the side edge of the sheets and the edge portion of the first and second air nozzles  26 A and  26 B is so little that air does not escape somewhere else so much but is spouted securely to the sides of the sheets. 
   Here, the vicinity of take-out unit  30  with respect to positions of the first and second air nozzles  26 A and  26 B is defined to be a location that is closer to the front edge side of the sheets stacked on sheet-feeding member  22  than their center PC and that is in the vicinity where the top one of the sheets P contacts with take-out unit  30 . 
   The first and second air nozzles  26 A and  26 B spout air from a compressor to separate the sheets from each other and to make some of them float. The air may be supplied to the first and second air nozzles  26 A and  26 B by one common compressor or separate ones. 
   As described above, since depression unit  27  depresses the rear edge side of the sheet stacked on sheet-feeding member  22  and air spout unit  26  spouts air to both sides of the sheets, the air remains at the front edge portion to keep the sheets P separate from each other. 
   Take-out unit  30  takes out a sheet from the front edge portion of the sheets in the longitudinal or taking-out direction while air spout unit  26  spouts air to the sheets. Take-out unit  30  is provided with take-out rotor  31  and reverse rotation rotor  32 . Take-out rotor  31  rotates in the forward direction to take out a sheet on the top surface of the sheets as shown with an arrow in  FIG. 2 . Reverse rotation rotor  32  rotates in the direction to return excessive sheets taken out by take-out rotor  31  to sheet-feeding member  22  as also shown with an arrow in  FIG. 2 . Reverse rotation rotor  32  is provided underneath take-out rotor  31  and closer to sheet-feeding member  22  than to take-out rotor  31 . 
   Take-out rotor  31  and reverse rotation rotor  32  are driven independently by rotation drive devices, respectively. A angular velocity ratio of take-out rotor  31  to reverse rotation rotor is set to approximately 10:7, for instance. In this embodiment, take-out rotor  31  with a diameter of 80 mm rotates at a speed of 1,200 r.p.m. (rotations per minute) while reverse rotation rotor  32  with a diameter of 40 mm rotates at a speed of 800 r.p.m. 
   Take-out rotor  31  and reverse rotation rotor  32  are provided with suction holes  31   a  and  32   a  made at their sheet-contacting surfaces to suck sheet P, respectively. Further, take-out rotor  31  is set to be substantially the same in suction pressure, e.g., 35 kPa through 40 kPa, as reverse rotation rotor  32 . 
   Since take-out rotor  31  is also substantially the same in structure as reverse rotation rotor  32 , the structure of reverse rotation rotor  32  will be described below. As shown in  FIG. 5 , reverse rotation rotor  32  has cylinder-like rotor  32 X and stator  32   b  in the inside of cylinder-like rotor  32 X. Stator  32   b  is provided with cut-out portion  32   c  opposite to take-out rotor  31  to define a chamber. 
   With this structure, when cylinder-like rotor  32 X rotates, only suction holes  32   a  facing cut-out portion  32   c  suck air so that sheet P sucked by suction holes  32   a  is conveyed back to sheet-feeding member  22  in the predetermined direction. 
   A friction coefficient of the surface of take-out rotor  31  is set to be larger than that of reverse rotation rotor  32 . The surface of take-out rotor  31  is made of a rather high friction coefficient material such as rubber while that of reverse rotation rotor  32  is a metallic material such as stainless steel. 
   In take-out unit  30 , take-out rotor  31  rotates to take out the top one of sheets P placed on sheet-feeding member  22 . Thus, the sheet P in contact with the surface of take-out rotor  31  is taken out by the high friction. 
   Reverse rotation rotor  32 , on the other hand, rotates in the direction to avoid sending out sheet P. Reverse rotation rotor  32  sucks, and returns to sheet feeder  20 , sheets P that are not sucked by take-out rotor  31 . Thus, this prevents take-out rotor  31  from delivering excessive sheets to conveyor  3 . Take-out rotor  31  can take out sheets P at a speed of 275 m/sec, for instance. 
   A method of taking out sheets will be explained below with reference to sheet take-out apparatus  2  set forth above. 
   First, upper surface position detection lever  23  detects the upper surface of a bundle of sheets placed on sheet-feeding member  22 . In response to detection results provided by upper surface position detection lever  23 , movable sheet-feeding member  21  is controlled to lift up sheet-feeding member  22  until the upper surface of the sheets reaches a proper position as shown in  FIG. 6 . 
   When the upper surface of the sheets reach to the proper position, air nozzle  27 A of depression unit  27  spouts air toward the sheets to depress the upper surface of the sheets in the direction against sheet-feeding member  22 . At the same time, the first and second air nozzles  26 A and  26 B of air spout unit  26  spout air toward both sides of the sheets. The air causes sheets P to separate from each other and to float. 
   As shown in  FIG. 7 , several sheets P positioned at the upper part of the bundle of sheets float on the front edge side close to take-out unit  30  due to the air from the first and second air nozzles  26 A and  26 B while the air from air nozzle  27 A prevents the rear edge portion of the sheets from floating. Since the sheets are depressed at the rear edge portion, the air spouted to the front edge side stays there to make the sheets P separate effectively. 
   As shown in  FIG. 8 , when the sheets P are separated at the front edge of the sheets, the rotation drive devices rotate take-out rotor  31  and reverse rotation rotor  32  in the predetermined directions. Suction holes  31   a  of take-out rotor  31  sucks and takes out the separated sheet P while suction holes  32   a  of reverse rotation rotor  32  also sucks excessive sheets that are not sucked by suction holes  31   a  and returns them back to sheet feeder  20 . This prevents take-out rotor  31  from taking out a plurality of sheets at a time. 
   Air spout unit  26  in the embodiment described above with reference to  FIG. 2  is provided with a pair of air nozzles  26 A and  26 B at both sides of stacked sheets but it may be provided with either air nozzle  26 A or  26 B. 
   As shown in  FIGS. 9 and 10 , however, in addition to the first and second air nozzles  26 A and  26 B, the third air nozzle  26 C may be further provided at a place that is lower (closer to sheet-feeding member  22 ) than those of the first and second air nozzles  26 A and  26 B and that is on the rear edge side in the longitudinal or taking-out direction of the sheets. Air may be supplied to the third air nozzle  26 C from the same compressor for the first and second air nozzles  26 A and  26 B or from a compressor different from it. 
   Air spout unit  26  provided with the three air nozzles can handle even the lower part of the sheets P and keep them separate from each other at the front edge portion of sheets P. Thus, take-out unit  30  is capable of avoiding taking out excessive sheets effectively. 
   As described above, in the sheet take-out apparatus and method of taking out sheets according to the embodiments, while a bundle of the sheets placed on the sheet-feeding member are depressed against the sheet-feeding member, air is spouted to the sides of a bundle of sheets in the longitudinal or taking-out direction. Thus, the air can be kept at the necessary portion of the sheets. 
   In other words, air is spouted from the upper position over the sheets to the rear edge portion of the sheets so that the rear edge of the sheets is depressed. Further, in this condition, air spouted to the front edge side of the sheets stay at the front edge side and keeps some sheets separate from each other at the front edge. Thus, irrespective of surface conditions of the sheets, the take-out of excessive sheets can be securely avoided. 
   The present invention provides a sheet take-out apparatus and a method of taking out sheets which are capable of taking out one necessary sheet at a time regardless of surface conditions of the sheets. 
   Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been changed in the details of construction and the combination and arrangement of components may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.