Patent Publication Number: US-7717416-B2

Title: Paper sheet separation and transfer apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of co-pending U.S. application Ser. No. 10/932,351, filed Sep. 2, 2004, and for which priority is claimed under 35 U.S.C. §121. This application is based upon and claims the benefit of priority under 35 U.S.C. §119 from the prior Japanese Patent Application No. 2003-311594, filed Sep. 3, 2003, the entire contents of both applications are incorporated herein by reference in their entireties. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a paper sheet separation and transfer apparatus which separates a plurality of stacked paper sheets such as postal matters, bills and plain-paper copies, one by one, and takes each sheet out onto a transfer path. 
   2. Description of the Related Art 
   As a conventional paper sheet separation and transfer apparatus, a separation and transfer apparatus having a separation unit to prevent overlapped paper sheet feeding has been known. (For example, refer to Jpn. Pat. Appln. KOKAI Publication No. 2003-81463.) This separation and transfer apparatus has a take-out roller which rotates and contacts a paper sheet at one end of a stack, and takes it out onto a transfer path, and a transfer path which transfers the taken-out paper sheet. On the transfer path of the downstream side of the take-out roller, a separation unit and a transfer unit are arranged close to each other along the paper sheet take-out direction. 
   The separation unit has a feed roller which contacts the paper sheet taken out onto the transfer path on the same side as the take-out roller and rotates forward, and a separation roller which is located opposite to the feed roller through the transfer path and separates second and subsequent paper sheets taken out together with the first sheet by giving them a reverse force (a tangential force). 
   The transfer unit has a drive roller which accepts the transfer direction end of a paper sheet passed through a nip between the feed roller and separation roller, and rotates forward, thereby pulling out the paper sheet from the nip of the separation unit and feeding it, and a pinch roller which is arranged opposite to the drive roller through the transfer path. 
   In the separation and transfer apparatus with the above structure, when stacked paper sheets are taken out onto the transfer path, the take-out roller is rotated first, and a paper sheet at one end of a stack is taken out onto the transfer path. In this case, by the friction between paper sheets, second and subsequent paper sheets may be taken out together with the first paper sheet. The taken-out second and subsequent paper sheets are separated by the separation unit, and transferred to a processing unit in a later stage through the transfer path. 
   The separation unit feeds forward the preceding first paper sheet by the feed roller, and rotates the separation roller in the reverse direction contacting the second and subsequent sheets overlapped with the first sheet, and separates these second and subsequent paper sheets by pushing them in the reverse direction. 
   However, in the above conventional unit, if the take-out roller takes out two paper sheets with different size and thickness, overlapped paper sheets may not by completely separated by one separation unit. 
   BRIEF SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a paper sheet separation and transfer apparatus which can separate and transfer stacked paper sheets with certainty. 
   In order to achieve the above object, according to an embodiment of the present invention, there is provided a paper sheet separation and transfer apparatus comprising a take-out roller which rotates and contacts a paper sheet at one end of a stack of a plurality of paper sheets, and takes out the paper sheet onto a transfer path; a first separation unit having a first feed roller which contacts the paper sheet taken out onto the transfer path and rotates forward, and a first separation roller which is pressed to the first feed roller through the transfer path, and separates second and following paper sheets taken out together with the first paper sheet by giving a reverse separating force; a second separation unit having a second feed roller which contacts the paper sheet passed through the first separation unit and rotates forward, and a second separation roller which is pressed to the second feed roller through the transfer path, and separates second and following paper sheets taken out together with the first paper sheet by giving a reverse separating force; a first detector which detects that a preceding paper sheet reaches the second separation unit; and a control unit which decelerates the peripheral speed of the first feed roller, when the first detector detects that a preceding paper sheet reaches the second separation unit. 
   According to another embodiment of the invention, there is provided a paper sheet separation and transfer apparatus comprising a take-out roller which rotates and contacts a paper sheet at one end of a stack of a plurality of paper sheets, and takes out the paper sheet onto a transfer path; a first separation unit having a first feed roller which contacts the paper sheet taken out onto the transfer path and rotates forward, and a first separation roller which is pressed to the first feed roller through the transfer path, and separates second and following paper sheets taken out together with the first paper sheet by giving a reverse separating force; a second separation unit having a second feed roller which contacts the paper sheet passed through the first separation unit and rotates forward, and a second separation roller which is pressed to the second feed roller through the transfer path, and separates second and following paper sheets taken out together with the first paper sheet by giving a reverse separating force; a state detection unit which detects the state that a plurality of paper sheets exist between the second feed roller and second separation roller; and a control unit which decelerates the peripheral speed of the first feed roller, when the state detection unit detects the state. 
   According to still another embodiment of the invention, there is provided a paper sheet separation and transfer apparatus comprising a take-out roller which rotates and contacts a paper sheet at one end of a stack of a plurality of paper sheets, and takes out the paper sheet onto a transfer path; a first separation unit having a first feed roller which contacts the paper sheet taken out onto the transfer path and rotates forward, and a first separation roller which is pressed to the first feed roller through the transfer path, and separates second and following paper sheets taken out together with the first paper sheet by giving a reverse separating force; a state detection unit which detects the state that a plurality of paper sheets exist between the first feed roller and first separation roller; and a control unit which decelerates the peripheral speed of the take-out roller, when the state detection unit detects the state. 
   Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
       FIG. 1  is a schematic illustration showing a separation and transfer apparatus according to a first embodiment of the present invention; 
       FIG. 2  is a block diagram of a control system which controls operation of the separation and transfer apparatus of  FIG. 1 ; 
       FIG. 3  is a flowchart for explaining a first operation example of the separation and transfer apparatus of  FIG. 1 ; 
       FIG. 4  is a flowchart for explaining a second operation example of the separation and transfer apparatus of  FIG. 1 ; 
       FIG. 5  is a schematic illustration showing a separation and transfer apparatus according to a second embodiment of the present invention; 
       FIG. 6  a flowchart for explaining a third operation example of the separation and transfer apparatus of  FIG. 5 ; 
       FIG. 7  is a graph showing changes with time of the rotation speed of a separation roller in the state that the separation roller is co-rotated; 
       FIG. 8  is a graph showing changes with time of the rotation speed of a separation roller during the separating operation; and 
       FIG. 9  is a flowchart for explaining a fourth operation example of the separation and transfer apparatus of  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Hereinafter, detailed explanation will be given on embodiments of the present invention with reference to the accompanying drawings. 
     FIG. 1  shows a schematic construction of a paper sheet separation and transfer apparatus  1  (hereinafter, simply referred to as a separation and transfer apparatus  1 ) according to the present invention. 
   The separation and transfer apparatus  1  has a housing  2  which contains a plurality of stacked paper sheets P. A take-out roller  3  is provided at the position contacting a paper sheet P 1  at one end of the stack of paper sheets P contained in the housing  2 . Each roller shown in  FIG. 1  has two rollers separated from each other in the axial direction. 
   The take-out roller  3  is fixed to the rotary shaft through a one-way clutch  4 , and the rotary shaft is fixed to the front end of a press arm  5 . The rotary shaft of a press motor  6  is fixed to the base end of the press arm  5 . Thus, the press arm  5  is swung by driving the press motor  6 , and the take-out roller  3  is pressed to the paper sheet P 1  at one end of the stack. The press arm  5  and press motor  6  function as a press mechanism of the present invention. 
   In this embodiment, a torque control motor is adopted for the press motor  6 , and the pressing force of the take-out roller  3  to the paper sheet P 1  can be changed optionally. The take-out roller  3  is freely rotatable in the arrow direction (the forward direction) in the drawing by the action of one-way clutch  4 . Therefore, when transferring the paper sheet P in the arrow T direction (forward) in the drawing, the take-out roller  3  rotates together with the paper sheet P, and does not generate a reverse force disturbing the transfer of the paper sheet P, that is, a force along the tangential direction of the take-out roller (hereinafter, simply referred to as a tangential force). 
   A take-out motor  9  is connected to the rotary shaft of the take-out roller  3  through a plurality of pulleys  7  and timing belts  8 . Namely, by driving the take-out motor  9 , the take-out roller  3  is rotated in the arrow direction in the drawing. In this embodiment, a position control motor is adopted for the take-out motor  9 , and the rotation speed, direction and amount (angle) of the take-out roller  9  can be controlled optionally. 
   On the opposite side of the housing  2  against the take-out roller  3 , a backup plate  10  is provided to move a plurality of paper sheets P in the stack by pressing a paper sheet P at the other end of the stack, and to supply a paper sheet P 1  at one end of the stack to a predetermined take-out position. The backup plate  10  is urged in the stacking direction by an actuator described later. 
   A guide member  11  is provided at the position adjacent to the housing  2 , or the position opposite to the front end of the take-out direction of a plurality of paper sheets P. The guide member  11  is bent toward the nip of a first separation unit described later, and functions to guide the front end of each paper P in the transfer direction to the nip. 
   When the take-out roller  3  pressed by the press motor  6  to the paper sheet P at one end of the stack is rotated forward by the take-out motor  9 , the paper sheet P 1  supplied by the backup plate  10  to the predetermined take-out position is taken out onto a transfer path  12 . In this time, by the friction between the paper sheets P, second and subsequent sheets may be taken out together with the first paper sheet P 1 . 
   On the transfer path  12  of the downstream side of the take-out roller  3 , a first separation unit  13 , a second separation unit  14  and a pull-out unit  15  are sequentially arranged close to each other along the transfer direction T. 
   The first separation unit  13  has a first feed roller  16  which contacts the paper sheet P taken out onto the transfer path  12  and rotates forward along the transfer direction T, and a first separation roller  17  which is arranged opposite to the first feed roller  16  through the transfer path  12 . The first separation roller  17  is pressed by a predetermined pressure to the first feed roller  16  in the state that no paper sheet P exists on the transfer path  12 . 
   The first feed roller  16  is arranged on the same side as the take-out roller  3  against the transfer path  12 , that is, the upper side of the transfer path  12  in the drawing. The first feed roller  16  is attached to the rotary shaft through a one-way clutch  18 . Therefore, when the paper sheet P is transferred in the arrow T direction along the transfer path  12 , the first feed roller  16  rotates freely forward together with the paper sheet P, and does not generate a force (a tangential force) in the direction of disturbing the transfer of the paper sheet P. 
   A first feed motor  21  is connected to the rotary shaft of the first feed roller  16  through a plurality of pulleys  19  and timing belts  20 . Namely, by driving the first feed motor  21 , the first feed roller  16  is rotated. In this embodiment, a position control motor is adopted for the first feed motor  21 , and the rotation speed, direction and amount (angle) of the first feed roller  16  can be controlled optionally. 
   To the rotary shaft of the first separation roller  17 , a first separation motor  24  is connected through a plurality of pulleys  22  and timing belts  23 . The first separation motor  24  gives the first separation roller  17  a force in the direction to rotate the first separation roller  17  in the arrow direction in the drawing (the reverse direction). In this embodiment, a torque control motor is adopted for the first separation motor  24 , and a reverse separating force given by the first separation motor  24  to the first separation roller  17 , that is, a separating force given by the first separation roller  17  to the paper sheet P in the tangential direction (hereinafter, sometimes referred to as a separation tangential force) can be changed optionally. 
   However, a separation force given by the first separation motor  24  to the first separation roller  17  is set to the degree that the first separation roller  17  rotates forward together with the first feed roller  16 , in the state that there is no paper sheet P to transfer on the transfer path  12 , or the state that one paper sheet P is transferred. In other words, even if the first separation motor  24  tries to rotate the first separation roller  17  in the reverse direction, when no paper sheet P exists in the nip  13   a  in the space to the first feed roller  16 , or when one paper sheet P exists, the first separation roller  17  is rotated forward. 
   When a plurality of paper sheets P is fed overlapped to the first separation unit  13 , the preceding first paper sheet P 1  is fed in the arrow T direction by the first feed roller  16  around which the first paper sheet P 1  is rotated forward, the first separation roller  17  gives a separating force (a separating tangential force) reverse to the direction T to the second and subsequent paper sheets P taken out together with the first paper sheet P 1  in being overlapped therewith, and the second and subsequent paper sheets P are separated from the first paper sheet P 1 . Of course, if the second and subsequent paper sheets P are not taken out together when the first paper sheet P 1  is taken out, the first separation roller  17  rotates together with the first paper sheet P 1 , and the first paper sheet P 1  passes through the first separation unit  13 . 
   The second separation unit  14  provided on the downstream side of the first separation unit  13  along the paper sheet transfer direction T has the same structure as the first separation unit  13 . Thus, the same reference numerals are given to the components having the similar functions, and detailed explanation will be omitted. However, to simplify the explanation, different reference numerals are given to specific components. Namely, the second separation unit  14  has a second feed roller  25  driven and rotated by a second feed motor  27 , and a second separation roller  26  given a separation force by a second separation motor  28 . A position control motor is adopted for the second feed roller  27 , and a torque control motor is adopted for the second separation motor  28 . The second separation unit  14  functions to separate a plurality of paper sheets which are fed overlapped without being separated by the first separation unit  13 . 
   The pull-out unit  15  provided on the downstream side of the second separation unit  14  along the transfer direction T has a pull-out roller  29  and a pinch roller  30 . The pull-out roller  29  is provided on the same side as the take-out roller  3  against the transfer path  12  (the upper side in the drawing). The pinch roller  30  is pressed by a predetermined pressure to the pull-out roller  29  through the transfer path  12 . 
   A pull-out motor  33  is connected to the rotary shaft of the pull-out roller  29  through a plurality of pulleys  31  and timing belts  32 . Namely, by driving the pull-out motor  33 , the pull-out roller  29  is rotated in the arrow direction in the drawing. In this embodiment, a position control motor is adopted for the pull-out motor  33 , and the rotation speed and amount (angle) of the pull-out roller  29  can be controlled optionally. 
   When the front end in the transfer direction of the paper sheet P passed through the second separation unit  14  is fed to the nip between the pull-out roller  29  and pinch roller  30 , the paper sheet P is pulled out from the second separation unit  14  by the pull-out unit  15 . The paper sheet P pulled out by the pull-out unit  15  is transferred to a not-shown processing unit in the later stage and processed there. 
   On the transfer path  12 , a first sensor  34  (a first detector) and a second sensor  35  (a second detector) are provided. Each sensor  34  and  35  has a light emitting part and a light receiving part, detects the passage of the paper sheet P by the fact that the paper sheet P interrupts the light from the light emitting part to the light receiving part. 
   The first sensor  34  is provided at the position where the light crosses the transfer path  12  between the nip  13   a  located between the first feed roller  16  and first separation roller  17  (hereinafter, called the nip  13   a  of the first separation unit  13 ) and a nip  14   a  located between the second feed roller  25  and second separation roller  26  (hereinafter, called the nip  14   a  of the second separation unit  14 ). The second sensor  35  is provided at the position where the light crosses the transfer path  12  between the nip  14   a  of the second separation unit  14  and a nip  15   a  located between the pull-out roller  29  and pinch roller  30  (hereinafter, called the nip  15   a  of the pull-out unit  15 ). 
     FIG. 2  shows a block diagram of a control system which controls the operation of the separation and transfer apparatus  1  with the above structure. 
   The separation and transfer apparatus  1  has a control unit  40  which controls the apparatus. The control unit  40  is connected with a mechanism controller  41 , a motor controller  42  and a drive amplifier  43 . The mechanism controller  41  is connected with an actuator  44  of the aforementioned backup plate  10 . 
   The motor controller  42  is connected with the press motor  6  which presses the take-out roller  3  to the paper sheet P 1 , the take-out motor  9  which rotates the take-out roller  3 , a first feed motor  21  which rotates the first feed roller  16 , a first separation motor  24  which gives the first separation roller  17  a reverse separation force, the second feed motor  27  which rotates the second feed roller  25 , the second separation motor  28  which gives the second separation roller  26  a reverse separation force, and a pull-out motor  33  which rotates the pull-out roller  29 . 
   The drive amplifier  43  is connected with the aforementioned first sensor  34  and second sensor  35 . Thus, the output signals from the sensors  34  and  35  are sent to the control unit  40 . 
   Next, a first operation example of the separation and transfer apparatus  1  with the above-mentioned structure will be explained with reference to the flowchart of  FIG. 3 . 
   First, the control unit  40  controls the motor controller  42 , drives the press motor  6 , first feed motor  21 , first separation motor  24 , second feed motor  27 , second separation motor  28  and pull-out motor  33 , presses the take-out roller  3  to the paper sheet P 1  at one end of the stack by a predetermined pressure, rotates forward the first feed roller  16 , second feed roller  25  and pull-out roller  29  at a predetermined speed, and gives a predetermined separation torque to the first separation roller  17  and second separation roller  26  (Step  1 ). In this state, as the paper sheet P is not transferred through the transfer path  12 , the first separation roller  17  rotates together with the first feed roller  16 , and the second separation roller  26  rotates together with the second feed roller  25 . 
   In this state, the control unit  40  controls the motor controller  42 , drives the take-out motor  9  and rotates the take-out roller  3  forward at a predetermined speed, and takes out the paper sheet P 1  at one end of the stack contacted and rotated by the take-out roller  3  onto the transfer path  12  (Step  2 ). In this case, the second and subsequent paper sheets may be taken out overlapped together with the first paper sheet P 1  onto the transfer path  12 . 
   In steps  1  and  2 , the motor controller  42  controls the rotation speeds of the motors  9 ,  21 ,  27  and  33 , so that the peripheral speeds of the take-out roller  3 , first feed roller  16 , second feed roller  25  and pull-out roller  29  become V 1 , V 2 , V 3  and V 4 , respectively. Here, the motor controller  42  controls the rotation speeds of the rollers  3 ,  16 ,  25  and  29 , so that the peripheral speeds V 1 , V 2 , V 3  and V 4  of the rollers satisfy the following expression:
 
V1≦V2≦V3≦V4
 
   As explained above, by making the peripheral speeds of the rollers  3 ,  16 ,  25  and  29  different, a transfer gap can be taken between the paper sheets P taken out continuously onto the transfer path  12 . Further, by making the speeds of the rollers different to satisfy the above expression, a buckle in the paper sheet P on the way of transfer can be prevented. However, if the peripheral speed difference is too large, the transfer gap will become unnecessarily large. Therefore, it is necessary to adjust the speed difference to an appropriate value. 
   When a certain time passes after detecting that the front end in the transfer direction of the paper sheet P 1  taken out onto the transfer path  12  in step  2  has reached the first sensor  34  by passing through the nip  13   a  of the first separation unit  13  (Step  3 ; YES), the control unit  40  decelerates the take-out motor  9  and first feed motor  21 , and decelerates the peripheral speeds of the take-out roller  3  and first feed roller  16  (Step  4 ). After the deceleration, the peripheral speeds V 1 ′ and V 2 ′ of the take-out roller  3  and feed roller  16  satisfy the following expression:
 
V1′≦V2′&lt;V2
 
   The above certain time is the time from the arrival of the front end in the transfer direction of the paper sheet P 1  at the first sensor  34  to the arrival at the nip  14   a  of the second separation unit  14 , that is, the time determined by the peripheral speed of the first feed roller  16  and the distance from the position where the first sensor  34  crosses the transfer path  12  to the nip  14   a  of the second separation unit  14 . In other words, in step  4 , the control unit  40  decelerates the take-out motor  9  and first feed motor  21  at the timing that the front end of the paper sheet P 1  in the transfer direction reaches the nip  14   a  of the second separation unit  14 . The term “decelerate” mentioned here and the term “decelerate” described in the Claims indicate the control to decelerate the roller rotating forward, and include all states from stop of the roller after deceleration to start of rotation in the reverse direction. 
   Thereafter, the control unit  40  detects that the rear end of the paper sheet P 1  in the transfer direction passes through the first sensor  34  (Step  5 ; YES), and accelerates the take-out motor  9  and first feed motor  21  to return the peripheral speeds of the take-out roller  3  and first feed roller  16  to V 1  and V 2 , respectively (Step  6 ). Then, the control unit  40  repeats the control of steps  2  to  6  until all paper sheets P contained in the housing  2  are taken out (Step  7 : NO). 
   Further, the control unit  40  monitors the time that the paper sheet P passes through the first sensor  34 , while executing the control in the above steps  2  to  6 , and when the passing time becomes longer than a certain predetermined value continuously over a predetermined numbers of time, the control unit  40  judges that there is a possibility that the overlapped feed of the paper sheet P occurs frequently exceeding the separating capacity in the first separation unit  13 , and controls the press motor  6  to decrease the pressing force of the take-out roller  3  to the paper sheet P. 
   As describe above, in the first operation example, the peripheral speeds of the take-out roller  3  and first feed roller  16  are “decelerated” at the time when the front end in the transfer direction of the paper sheet P 1  taken out onto the transfer path  12  reaches the nip  14   a  of the second separation unit  14 , and if there is second and subsequent paper sheets taken out together with the paper sheet P 1 , it is possible to prevent a defect of causing a wrinkle in the paper sheet P on and after the second sheet during the separating operation in the second separation unit  14 . 
   Conversely, when the “decelerate” control explained in the first operation example is not adopted, for example, in the state that the first paper sheet P 1  and second paper sheet P 2  are being separated in the second separation unit  14  and that the rear end of the paper sheet P 1  in the transfer direction passes through the nip  13   a  of the first separation unit  13 , the front end of the second paper sheet P 2  is returned to the reverse direction by the second separation roller  26  of the second separation unit  14 , and the rear end of the second paper sheet P 2  is fed forward by the first feed roller  16  of the first separation unit  13 , and the second paper sheet P 2  buckles and causes a wrinkle between two nips  13   a  and  14   a.    
   Namely, in this case, if the above mentioned “decelerate” control of the present invention is adopted, the peripheral speed of the first feed roller  16  which feeds forward the rear end of the second paper sheet P 2  can be delayed at least, decreasing the possibility of buckling the second paper sheet P 2  between the nips  13   a  and  14   a . As described above, the term “decelerate” mentioned here includes “stop” and “reverse”, and for example, when the paper sheet P is a relatively flimsy bill, it is possible to prevent substantially a defect of causing a wrinkle in the second paper sheet P 2  by “stopping” the take-out roller  3  and “reversing” the first feed roller  16  to meet the peripheral speed of the second separation roller  26 . 
   Namely, it is necessary to select appropriate degree of “deceleration” of the take-out roller  3  and first feed roller  16  according to the physical characteristics of the paper sheet P, such as flexibility, material, thickness and hardness. For example, when separating and transferring relatively thick and hard paper sheets P such as postal matter, the above-mentioned buckling can be prevented simply by “decelerating” slightly the take-out roller  3  and first feed roller  16 . The buckling problem may also be solved by decreasing the pressing force of the take-out roller  3  by the press motor  6  instead of “decelerating” the take-out roller  3 . 
   In the above-mentioned first operation example, explanation has been given of the case that two rollers  3  and  16  are “decelerated” by monitoring only the output of the first sensor  34 . However, the separation and transfer apparatus  1  of this embodiment has two separation units  13  and  14 , and it is unknown which separation unit separates the second and subsequent paper sheets P taken out together with the first paper sheet P 1 . Thus, the processing time of the paper sheet P may become unnecessarily long under certain conditions. 
     FIG. 4  is a flowchart showing a second operation example, in which the outputs of the first and second sensors  34  and  35  are monitored, the output signals of two sensors  34  and  35  are ored, and two rollers  3  and  16  are “decelerated”. This second operation example is the same as the aforementioned first operation example except that the processing of step  5  is different. 
   Namely, in the processing of step  5 ′ different from the first operation example, the control unit  40  monitors the output of the first sensor  34  and detects that the rear end of the first paper sheet P 1  in the transfer direction passes, and monitors the output of the second sensor  35  and detects that the rear end of the first paper sheet P 1  in the transfer direction passes. When one of the first and second sensors  34  and  35  detects the passage of the rear end of the first paper sheet P 1  in the transfer direction (Step  5 ′; YES), the control unit  40  return the peripheral speeds of the rollers  3  and  16 . 
   By the above operation of the control unit  40 , for example, when the second paper sheet P 2  is taken out together with the first paper sheet P 1  and these two overlapped sheets are not separated by the first separation unit  13  but separated by the second separation unit  14 , the control unit  40  “decelerates” continuously two rollers  3  and  16  until the rear end of the second paper sheet P 2  in the transfer direction passes through the first sensor  34  in the first operation example, but in the second operation example, the peripheral speeds of the rollers  3  and  16  can be returned to the original speed at the time when the second sensor  35  detects the passage of the rear end of the first paper sheet P 1  in the transfer direction. Namely, in this case, the time of “decelerating” the two rollers  3  and  16  can be reduced by adopting the second operation example. 
   As described above, by adopting the second operation example, the same effect as that obtained when adopting the first operation example can be obtained, and the processing time can be reduced. 
     FIG. 5  shows a schematic construction of a separation and transfer apparatus  50  according to a second embodiment of the present invention. In the separation and transfer apparatus  50 , the first and second separation motors  24  and  28  contain encoders  51  and  52  (state detection unit), respectively. In other words, the separation and transfer apparatus  50  has the same structure as the aforementioned separation and transfer apparatus  1  except that the encoders  51  and  52  are used instead of the first and second sensors  34  and  35 . Thus, the same reference numerals are given to the components having the same functions as in the separation and transfer apparatus  1 , and detailed explanation of these components will be omitted. 
   The encoder  51  contained in the first separation motor  24  detects the rotation speed of the first separation roller  17 , and the encoder  52  contained in the second separation motor  28  detects the rotation speed of the second separation roller  26 . The output ends of two encoders  51  and  52  are connected to the control unit  40 . In other words, in this embodiment, the control unit  40  always monitors the rotation speeds of the first and second separation rollers  17  and  26  through the encoders  51  and  52 . 
     FIG. 6  shows a flowchart for explaining a third operation example of the separation and transfer apparatus  50  with the above structure. This third operation example is basically the same as the first operation example except that the state of the paper sheet P is detected by the encoder  52 . 
   Namely, after rotating the take-out roller  3  and taking out the first paper sheet. P 1  (Steps  1  and  2 ), the control unit  40  monitors the output of the encoder  52  contained in the second separation motor  28  (Step  3 ), regards the drop of the rotation speed of the second separation roller  26  as a trigger (Step  3 ; YES), “decelerates” the take-out motor  9  and first feed motor  21 , and “decelerates” the peripheral speeds of the take-out roller  3  and first feed roller  16  (Step  4 ). The term “decelerate” mentioned here includes “stop” and “reverse” as in the first embodiment. 
   When no paper sheet P exists in the nip  14   a  and when one paper sheet P exists in the nip  14   a , the second separation roller  26  rotates together with the second feed roller  25  at the same speed.  FIG. 7  shows changes with time of the rotation speed of the second separation roller  26  in the state rotated together with the second feed roller  25 . On the other hand, when a plurality of overlapped paper sheets P passes through the nip  14   a  of the second separation unit  14 , that is, when a plurality of paper sheets P is separated by the second separation unit  14 , the rotation speed of the second separation roller  26  is changed with time as shown in  FIG. 8 . Namely, by monitoring the changes in the rotation speed of the second separation roller  26  through the encoder  52 , it is possible to detect the state of the paper sheet P passing through the nip  14   a  of the second separation unit  14 . 
   After “decelerating” two rollers  3  and  16  in step  4 , the control unit  40  regards the return of the rotation speed of the second separation roller  26  to the original speed (the arrow A in  FIG. 8 ) as a trigger (Step  5 ; YES), judges that the first and second paper sheets P 1  and P 2  are separated, and accelerates the take-out motor  9  and first feed motor  21  so as to return the peripheral speeds of the take-out roller  3  and first feed roller  16  to V 1  and V 2 , respectively (Step  6 ). 
   The control unit  40  repeats the controls of steps  2  to  6  until all paper sheets P contained in the housing  2  are taken out (Step  7 ; NO). 
   When the rotation speed of the second separation roller  26  is lowered (Step  3 ; YES), the control unit  40  controls the first separation motor  24  to reduce the separation force given to the first separation roller  17 . Namely, when the rotation speed of the second separation roller  26  is lowered as described above, the separation of the paper sheet P 2  in the second separation unit  14  can be judged, and the separating operation in the first separation unit  13  becomes basically unnecessary. 
   Further, when the rotation speed of the second separation roller  26  is lowered (Step  3 ; YES), the control unit  40  controls the press motor  6  to decrease the pressing force of the take-out roller  3  on the paper sheet P 2 . By this operation, the forward force (tangential force) given to the separated paper sheet P 2  can be decreased further, and the paper sheet P 2  can be easily returned in the reverse direction. 
   The control unit  40  regards the return of the rotation speed of the second separation roller  26  to the original speed as a trigger (Step  5 ; YES), judges that the separating operation is finished, returns the separation force given to the first separation roller  17  to the original value, and returns the pressing force of the take-out roller  3  to the paper sheet P to the original value. 
   By operating the separation and transfer unit  50  according to the third operation example as explained above, the same effect as the first operation example can be obtained, and the state of the paper sheet P in the second separation unit  14  can be grasped more exactly, enabling more reliable separation and transfer. 
   In the above third operation example, explanation has been given on a method of preventing a wrinkle caused by the buckling of the paper sheet P 2  between the nips  13   a  and  14   a  of the first and second separation units  13  and  14 , by monitoring the state of the paper sheet P in the second separation unit  14 . The paper sheep P may buckle between the position where the take-out roller  3  contacts and rotates with the paper sheet P, and the nip  13   a  of the first separation unit  13 . 
     FIG. 9  is a flowchart showing a fourth operation example for preventing a buckle of the paper sheet P between the take-out roller  3  and nip  13   a . According to the drawing, after the first paper sheet P 1  is taken out onto the transfer path  12  (Steps  1 ,  2 ), the control unit  40  regards the drop of the rotation speed of the first separation roller  17  of the first separation unit  13  as a trigger (Step  3 ; YES), and controls the take-out motor  9  to “decelerate” the take-out roller  3  (Step  4 ). The term “deceleration” includes “stop” and “reverse”. 
   The control unit  40  regards the return of the rotation speed of the first separation roller  17  to the original speed as a trigger after the end of the separating operation in the first separation unit  13  (Step  5 ; YES), and controls the take-out motor  9  to return the peripheral speed of the take-out roller  3  to the original speed (Step  6 ). The control unit  40  repeats the control of steps  2  to  6  until all paper sheets P contained in the housing  2  are taken out (Step  7 ; NO). 
   When the rotation speed of the second separation roller  26  is lowered (Step  3 ; YES), the control unit  40  controls the first separation motor  24  to reduce the separation force given to the first separation roller  17 . Namely, when the rotation speed of the second separation roller  26  is lowered as described above, the separation of the paper sheet P 2  in the second separation unit  14  can be judged, and the separating operation in the first separation unit  13  becomes basically unnecessary. 
   In addition, when the rotation speed of the first separation roller  17  is lowered, the control unit  40  controls the first separation motor  24  and reduces the separating force given to the first separation roller  17 . Namely, when the rotation speed of the first separation roller  17  is lowered, the rotation speed of the take-out roller  3  is decelerated, the pressing force of the take-out roller  3  is reduced, and the paper sheet can be easily separated. Therefore, the paper sheet is prevented from being moved back excessively, by reducing the separating force of the first separation roller  17 . 
   When the rotation speed of the first separation roller  17  is lowered (Step  3 ; YES), the control unit  40  controls the press motor  6  so as to lower the pressing force of the take-out roller  3  on the paper sheet P, and makes it easy to return the paper sheet P 2  in the reverse direction. Further, when the rotation speed of the first separation roller  17  is returned to the original speed (Step  5 ; YES), the control unit  40  controls the press motor  6  so as to return the pressing force of the take-out roller  3  to the original value. 
   As explained above, in the fourth operation example, since the take-out roller  3  is “decelerated” and the pressing force of the take-out roller  3  is lowered at the time when the separating operation is started in the first separation unit  13 , the second paper sheet P 2  taken out together with the first paper sheet P 1  can be easily returned, and the buckling of the paper sheet P 2  between the nip of the take-out roller  3  and nip  13   a  of the first separation unit  13  can be prevented. 
   Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 
   For example, in the above embodiment, explanation has been given of the case that the overlapped state of paper sheet P is detected by using the sensors  34  and  35  or encoders  51  and  52 . The invention is not to be limited to this. The overlapped state of paper sheet P may be detected by detecting the thickness of paper sheet P. Further, the second embodiment uses the encoders  51  and  52  of the type incorporated in the separation motors  24  and  28 , but an external encoder may be used. Or, it is permitted to use a tachogenerator for detecting the rotation speed. 
   Further, the stacking direction of the paper sheet P is shown vertical in  FIG. 1  and  FIG. 5 , but the horizontal direction is permitted, and the stacking is not to be limited to the gravity direction. Further, in the above embodiment, the paper sheets P are taken out one by one onto the transfer path  12  by contacting and rotating the take-out roller  3  with the stacked paper sheets P, but a take-out belt can be used instead of the take-out roller  3 . It is also permitted to use a pair of pull-out belts instead of the pull-out roller  29  and pinch roller  30 .