Patent Publication Number: US-2007096383-A1

Title: Rubber roller, and paper sheet take-out apparatus including the rubber roller

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2005-319828, filed Nov. 2, 2005, the entire contents of which are incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a rubber roller to contact and rotates with a paper sheet, and a paper sheet take-out device including the rubber roller.  
      2. Description of the Related Art  
      As a conventional paper sheet take-out apparatus, there is a known apparatus, which takes out a stack of paper sheets one by one, and feeds the paper sheets to a processor in a later state.  
      This take-out apparatus has a stacker to house paper sheets stacked upright, a take-out roller pressed to contact a paper sheet at one end of the stacking direction of the paper sheets housed in the stacker, and a separation unit which separates paper sheets doubly taken out by receiving and passing the taken-out paper sheets through a nip (e.g., Jpn. Pat. Appln. KOKAI Publication No. 2003-341860).  
      The take-out roller rotates and contacts a paper sheet at one end of the stacking direction, and takes out the paper sheet by the frictional force generated between the peripheral surface and the paper sheet surface. At this time, if the paper sheet at one end of the stacking direction is inclined when contacting the take-out roller, the take-out roller rotates by contacting the paper sheet at the edge, and insufficient frictional force is applied to the paper sheet. If the rotation of the take-out roller is continued with the edge contacting the paper sheet, the take-out roller will be unevenly worn, the edge of the roller will become round, and the contact area of the take-out roller to an upright paper sheet will become smaller.  
      When the frictional force of the take-out roller to a paper sheet is insufficient, a paper sheet cannot be normally taken out. If the contact pressure of the take-out roller to a paper sheet is increased with time, the possibility of multiply feeding two or more overlapped paper sheets is increased.  
     BRIEF SUMMARY OF THE INVENTION  
      It is an object of the invention to provide a rubber roller to stably generate a sufficient frictional force regardless of the state of a paper sheet to contact, and a paper sheet take-out apparatus including the rubber roller.  
      In order to achieve the above object, a rubber roller according to an embodiment of the invention rotates by contacting a paper sheet, has an outer layer made of rubber material of JIS-A with a hardness over 35 Ha and below 90 Ha, and an inner layer provided inside the outer layer and made of non-foamed rubber material of JIS-A with a hardness over 5 Ha and below 25 Ha.  
      According to the rubber roller of the invention, the hardness of the outer layer is set to over JIS-A 35 Ha and below 90 Ha to ensure a sufficient wear proof, and the inner layer hardness is set soft over JIS-A 5 Ha and below 25 Ha. Therefore, the rubber roller is configured to make contact with a paper sheet stably and sufficiently widely by deforming the inner surface according to the state (e.g., inclination) of a paper sheet to make contact with the outer surface, and a sufficient friction force is applied to the paper sheet surface irrespectively of the state of the paper sheet. This eliminates the necessity of a mechanism to move the rubber roller according to the changes in the state of the paper sheet, simplifies the structure of the apparatus, reduces the manufacturing cost of the apparatus, and reduces the size of the apparatus. Moreover, the periphery of the roller stably contacts a paper sheet, and the edge of the outer layer does not contact a paper sheet and is not unevenly worn, and a decrease in the frictional force with time is prevented.  
      Further, a rubber roller according to an embodiment of the invention has a substantially cylindrical roller body which is made of rubber material, has an outer surface to contact a paper sheet, and a remover which is made soft by partially removing the roller body, to make the outer surface sufficiently contact a paper sheet by deforming the roller body to meet the state of a paper sheet to contact.  
      According to the rubber roller of the invention, since a remover made by removing a part of the roller body is provided, the roller body is made soft in an area of the remover, the roller body is easily deformed to meet the state (e.g., inclination) of the paper sheet contacting the outer surface, and the outer surface of the roller contacts the paper sheet stably and sufficiently widely.  
      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 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 top plane view showing the structure of a paper sheet take-out apparatus according to an embodiment of the invention;  
       FIG. 2  is a front view of the take-out apparatus of  FIG. 1 , viewed from the upstream side of a direction of taking out paper sheets;  
       FIG. 3  is a side view of the take-out apparatus of  FIG. 1 , viewed from one end of a direction of stacking paper sheets;  
       FIG. 4  is a view showing a paper sheet inclined to a take-out roller, and wear of the take-out roller;  
       FIG. 5  is a view showing a paper sheet inclined to a backup plate, and wear of the take-out roller;  
       FIG. 6  is a sectional view showing a take-out roller according to a first embodiment of the invention;  
       FIG. 7  is a partially enlarged sectional view for explaining a barrier layer of the take-out roller of  FIG. 6 ;  
       FIG. 8  is a graph for explaining the characteristics of an outer layer of the take-out roller of  FIG. 6 ;  
       FIG. 9  is a graph for explaining the characteristics of an inner layer of the take-out roller of  FIG. 6 ;  
       FIG. 10  is s sectional view showing a take-out roller according to a second embodiment of the invention;  
       FIG. 11  is a sectional view showing a modification of the take-out roller of  FIG. 10 ;  
       FIG. 12  is a view showing the state that a paper sheet is separated by a rubber roller according to a third embodiment of the invention;  
       FIG. 13  is a view showing the state that a paper sheet is fed out by rotating the rubber roller of  FIG. 12  in the forward direction;  
       FIG. 14  is a view showing a first modification of the rubber roller of  FIG. 12 ; and  
       FIG. 15  is a view showing a second modification of the rubber roller of  FIG. 12 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Embodiments of the invention will be explained in detail hereinafter with reference to the accompanying drawings.  
       FIG. 1  is a top plane view showing the structure of a paper sheet take-out apparatus  1  (hereinafter simply called a take-out apparatus) according to an embodiment of the invention.  FIG. 2 a  front view of the take-out apparatus  1  of  FIG. 1 , viewed from the upstream side of a direction of taking out paper sheets P.  FIG. 3  is a side view of the take-out apparatus  1  viewed from a direction of stacking paper sheets P.  
      As shown in  FIG. 1 , the take-out apparatus  1  has a stacker  2  which houses the paper sheets P such as mail stacked upright, a take-out roller  4  (a rubber roller) which contacts and rotates with the paper sheet P 1  supplied to a take-out position at one end of a stacking direction (the left end in the drawing), and takes out the paper sheet P 1  in the substantially horizontal direction substantially orthogonal to the stacking direction (in the direction of the arrow T in the drawing), a floor belt  6  which is extended movably along the paper sheets P stacking direction in the state contacting the lower end sides of all paper sheets P housed in the stacker  2 , a backup plate  8  which is provided movably in the stacking direction in the state facing closely to the upper end of the paper sheet P 2  at the other end of the stacking direction (at the right end in the drawing) remote from the floor belt  6 , and a separation unit  10  (a separation mechanism) which separates the paper sheets P taken out by the take-out roller  24  one by one, and feed the paper sheet to a processor in a later state.  
      As shown in  FIG. 2 , the take-out roller  4  has a lower roller  4 L to contact the paper sheet P 1  at one end of the stacking direction in the area close to the lower end, and an upper roller  4 U to contact the paper sheet P 1  in the area close to the upper end. The lower roller  4 L and upper roller  4 U are provided rotatably along the predetermined direction about a rotation axis  5  (refer to  FIG. 1 ) extended in a substantially vertical direction, that is, the direction of taking out the paper sheet P 1  (in the direction of the arrow T in  FIG. 1 ).  
      The rotation axis  5  of the rollers  4 L and  4 U is pivotally fixed to the distal ends of arms  11 L and  11 U. The proximal ends of the arms  11 L and  11 U are pivotally fixed to a not-shown casing of the take-out apparatus  1 . Therefore, when the arms  11 L and  11 U are driven by motors  14 L and  14 U (refer to  FIG. 3 ) described later, the rollers  4 L and  4 U contact and separate from the paper sheet P 1  at one end of the stacking direction.  
      At the proximal ends of the arms  11 L and  11 U, sensors  12 L and  12 U are provided to detect the positions of the rollers  4 L and  4 U contacting the paper sheet P 1 , or the positions XL and XU of the rollers  4 L and  4 U along the stacking direction rotationally contacting the paper sheet P 1  at one end of the stacking direction, by detecting the rotational angles of the arm  11 .  
      At the proximal ends of the arms  11 L and  11 U, motors  14 L and  14 U are provided to swing the arms  11 L and  11 U through link mechanisms  13 L and  13 U (refer to  FIG. 3 ) are connected. The arms  11 L/ 11 U, link mechanisms  13 L/ 13 U and motors  14 L/ 14 U move the rollers  4 L and  4 U in the direction of stacking the paper sheet P.  
      As shown in  FIG. 3 , sensors  15 L and  15 U are provided at the middle of the link mechanisms  13 L and  13 U to detect the pressures of FL and FU of the rollers  4 L and  4 U contacting the paper sheet P 1 . The sensor  15 L detects the contact pressure FL of the lower roller  4 L to the paper sheet P 1 , and the sensor  15 U detects the contact pressure FU of the upper roller  4 U to the paper sheet P 1 . Namely, the rollers  4 L and  4 U are brought into contact with the paper sheet P 1  at a desired contact pressure, by driving the motors  14 L and  14 U by monitoring the outputs of the sensors  15 L and  15 U.  
      At the proximal end of the arms  11 L and  11 U, two pulleys  16  and  17  are provided as one unit rotatably and coaxially with the rotational axis of the arm  11 . An endless belt  18  wound on a pulley  4   a  provided on the rotation axis  5  of the rollers  4 L/ 4 U is wound on the pulley  16 . An endless belt  20  wound on a pulley  19   a  provided on the rotation axis of the motor  19  to simultaneously rotate the rollers  4 L and  4 L is provided on the other pulley  17 . Therefore, the lower roller  4 L and upper roller  4 U are rotated in a predetermined direction at a desired speed by driving the motor  19 .  
      The floor belt  6  has two endless belts extended over along the paper sheet P stacking direction in the front and rear sides of the apparatus. A motor  22  for driving the floor belt  6  in the forward and rearward directions along the stacking direction is provided on the rotation axis  6   a  of the roller (not shown) on which the belts are wound.  
      The backup plate  8  is provided slidably with respect to a rail  24  extended in the stacking direction, at a position close to the upper end of the paper sheet stack, in the rear side of the stacker  2  and remote from the floor belt  6 . The backup plate  8  is provided at a position opposite to the upper end of the paper sheet P 2  housed upright in the stacker  2  at the other end of the stacking direction. The backup plate  8  is moved in the stacking direction along the rail  24 , by a motor  26  connected through a not-shown driving mechanism.  
      The floor belt  6  driven by the motor  22  and the backup plate  8  driven by the motor  26  functions as a supply mechanism of the invention, which cooperates and moves the paper sheets stacker in the stacker  2  in the stacking direction, and supplies the paper sheet P 1  at one end of the stacking direction to the take-out position.  
      In the take-out apparatus  1 , as the take-out roller  4  takes out the stacked paper sheet to the conveying path sequentially from the paper sheet P 1  stacked at one end of the stacking direction, the floor belt  6  is driven whenever the paper sheet P is taken out, and the backup plate  8  is moved. In other words, the floor belt  6  and backup plate  8  are driven, so that the paper sheet P 1  at one end of the stacking direction is always supplied to the take-out position.  
      As shown in  FIG. 1 , the separation unit  10  has a feed roller  32  provided at a position rotationally contacting one side (the left side in  FIG. 1 ) of the paper sheet P taken out in the direction of the arrow T by the take-out roller  4 , and a separation roller  34  (rubber roller) provided opposite to the feed roller  32  with a predetermined gap through the paper sheet conveying path. The separation unit  10  has a motor  36  to rotate the feed roller  32  in the paper sheet feeding direction (forward), and a motor  38  to impart a reverse torque to the separation roller  34 .  
      An endless belt  33  is extended over a pulley  36   a  provided on the rotation axis of a motor  36  and a pulley  32   a  provided on the rotation axis of the feed roller  32 . An endless belt  35  is extended over a pulley  38   a  provided on the rotation axis of a motor  38  and a pulley  34   a  provided on the rotation axis of a separation roller  34 . Therefore, the feed roller is rotated forward by the motor  36 , and a reverse separation torque is imparted to the separation roller  34  by the motor  38 .  
      The take-out apparatus  1  has a control unit  40 , which monitors the outputs of the sensors  12 L,  12 U,  15 L and  15 U, and controls the driving of the motors  14 L,  14 U,  19 ,  22 ,  26 ,  36 , and  38 . The control unit  40  controls the motors  14 L and  14 U, and adjusts the contact pressures FL and FU of the upper and lower rollers  4 U and  4 L to optimum values, based on the detection results of the sensors  15 L and  15 U. The control unit  40  controls the motors  22  and  26 , moves the floor belt  6  and/or backup plate  8 , and adjusts the contact pressures FL and FU of the upper roller  4 U and/or lower roller  4 L to optimum values.  
      As the take-out apparatus  1  collectively inputs and processes several kinds of paper sheets P such as mail with different size and thickness, after several numbers of paper sheets P are stacked and set in the stacker  2 , the paper sheet P 1  stacked at one end of the stacking direction is rarely supplied in a state upright to the outer surface of the take-out roller  4 .  
      Therefore, as shown in  FIG. 2 , for example, if the paper sheets P set in the stacker are supplied to the take-out position in the state that the upper end side remote from the floor belt  6  is inclined to the roller  4 , the upper roller  4 U contacts the area close to the upper end of the paper sheet P 1  stacked at one end of the stacking direction, but the lower roller  4 L does not contact the paper sheet P. If the paper sheet P is continuously taken out in this state, the corner of the upper roller  4 U contacting the paper sheet P is partially worn. The inclination angle of the paper sheet P with a different size is not constant, and the corner of the upper roller is rounded as shown in  FIG. 4  when the wear advances.  
      When the wear of the upper roller  4 U advances to the state shown in  FIG. 4 , for example, the upper roller  4 U contacts the paper sheet P substantially at a point, and the frictional force between the upper roller  4 U and the surface of the paper sheet P becomes very small. In this time, the roller  4 L does not contact the paper sheet P, the frictional force of two take-out rollers  4  to the paper sheet P becomes very small.  
      Contrarily, if the paper sheet P set in the stacker  2  is supplied to the take-out position in the state inclined to the backup plate  8 , only the lower roller  4 L contacts the paper sheet P 1 , and the upper roller  4 U does not contact the paper sheet. If the paper sheet P is continuously taken out in this state, the corner of the lower roller  4 L is worn and rounded as shown in  FIG. 5 . Namely, as the lower roller  4 L contacts the paper sheet P at a point and the upper roller  4 U does not contact the paper sheet P, the frictional force of two take-out rollers  4  to the paper sheet P becomes very small.  
      The frictional force decrease caused by the partial wear of the take-out roller  4  gradually advances from the initial state of the roller, and the frictional force is gradually decreased from immediately after the start of using the roller. To prevent the decrease of the frictional force, it is considerable to gradually increase the contact pressure of the take-out roller  4  to the paper sheet P. However, if the contact pressure of the take-out roller  4  is increased, there arises another problem of mis-feeding of several paper sheets P. The partial wear of the take-out roller  4  reduces the life of the roller in a very short time.  
      Therefore, in an embodiment of the invention, even if the paper sheet P is supplied to the take-out position in the inclined state, the take-out roller  4  follows the inclination of the paper sheet P and changes the form, and the outer surface of the take-out roller  4  is brought into contact with the surface of the paper sheet P in a sufficient area, without increasing the contact pressure to the paper sheet P. Hereinafter, an explanation will be given on the take-out roller  4  according to a first embodiment of the invention with reference to  FIG. 6 .  
      As shown in  FIG. 6 , the take-out roller  4  has an outer layer  42  made of relatively hard rubber having a sufficient coefficient of kinetic friction to the surface of the paper sheet P to contact and being sufficiently wearproof, and an inner layer  44  provided inside the outer layer  42  and made of relatively soft rubber deformable by a weak force. Concretely, the take-out roller  4  of this embodiment is formed by bonding the inner layer  44  to the outer surface of a core member  41 , and bonding the outer layer  42  to the outer surface of the inner layer  44  through a barrier layer  46  shown partially enlarged in  FIG. 7 .  
      In particular, the outer layer  42  of the take-out roller  4  is made of natural rubber, EPDM rubber or urethane rubber of JISK 6253 type A (JIS-A) having the coefficient of kinetic friction 1.0-1.5 to the surface of copy paper or envelope to contact, and the hardness of 35-90 Ha.  
       FIG. 8  is a graph showing the relation between the hardness of the rubber of the outer layer  42  and the coefficient of kinetic friction to an envelope. As measuring conditions, the pressing load of the take-out roller  4  is 100 g, and the relative sliding speed of the roller surface to an envelope is 1 m/s. It is seen from the graph that as the rubber roller hardness increases, the coefficient of kinetic friction decreases.  
      If the hardness of the outer layer  42  is lower than 35 Ha, the wear proof of the rubber roller is largely decreased and the life of the roller is reduced. Contrarily, if the hardness of the outer layer  42  is higher than 90 Ha, the coefficient of kinetic friction of the rubber roller is rapidly decreased to be lower than the coefficient of static friction between envelopes (approximately 0.4 Ha), and an envelope cannot be taken out. Namely, by setting the hardness of the outer layer  42  to over 35 Ha and below 90 Ha, the wearproof characteristic sufficient to take out the paper sheet P can be ensured, and the coefficient of kinetic friction necessary to take out an envelope can be ensured.  
      The inner layer  44  is made of rubber material of JIS-A with the hardness of 5-25 Ha, such as butyl rubber or EPDM rubber. By making the inner layer  44  of the take-out roller  4  of relatively soft rubber, the take-out roller  4  can be easily deformed to follow the state of the paper sheet P contacting the outer surface of the outer layer  42  of the take-out roller  4 , and the outer surface of the outer layer  42  contacts the surface of the paper sheet P stably in a relatively wide area.  
       FIG. 9  is a graph showing the relationship between the coefficient of kinetic friction and the hardness of the inner layer  44  of the take-out roller  4  whose outer layer  42  is made of EPDM rubber with the hardness of 60 Ha, by taking the inclination angle of the paper sheet P to the take-out roller  4  as a parameter. It is seen from the graph that when the hardness of the inner layer  44  is set to over 5 Ha and below 25 Ha, a sufficiently large coefficient of kinetic friction can be obtained at each inclination angle.  
      Namely, if the hardness of the inner layer  44  is lower than 5 Ha, the rubber strength becomes insufficient, the rotation force of the axis is not transmitted to the rubber roller, and the roller is broken. Contrarily, if the hardness of the inner layer  44  is higher than 5 Ha, the rubber roller is insufficiently deformed at each inclination angle of an envelope, the coefficient of kinetic friction is not sufficiently increased, and the roller is partially worn. In other words, by setting the hardness of the inner layer  44  to over 5 Ha and below 25 Ha, the outer surface of the outer layer  42  stably contacts the paper sheet P inclined at various angles, and a sufficiently large frictional force can be applied to the paper sheet.  
      The inner layer  44  bonded to the outer surface of the metal bar  41  may be made of other elastic materials such as a sponge and gel, but a stress may be generated in the clearance to the core member  41  by the rotation of roller, and the rubber roller may be broken. Therefore, it is necessary to use a non-foamed rubber for the inner layer  44 .  
      The barrier layer  46  shown partially enlarged in  FIG. 7  is provided to prevent transfer of a plasticizer between the inner layer  44  and outer layer  42 . The barrier layer is made of material whose index of solubility (SP value) of a transfer component is largely different from the SP values of the plasticizer of the inner layer  44  and outer layer  42 . Namely, when different kinds of rubber contact for a relatively long time, it is known that a plasticizer is mainly transferred between the different kinds of rubber. Such a transfer of component occurs easily when the index of solubility of a transfer component is closer to that of a rubber.  
      Concretely, in the take-out roller  4  of this embodiment, a plasticizer such as dioctyl adipate (DOA) and diethyl phthalate (DEP) is transferred from the relatively soft inner layer  44  to the outer layer  42 , and the outer layer  42  may be denatured. The SP value of a plasticizer of the inner layer  44 , such as dioctyl adipate (DOA) and diethyl phthalate (DEP), is a relatively high value, for example, 8.7 or 10. Therefore, the barrier layer  46  is desirably made of resin such as ethylene resin terafluoride (PTFE, SP value 7.3), polyethylene (PE, SP value 7.9) and polypropylene (PP, SP value 7.9).  
      In this embodiment, the barrier layer  46  is made of rubber having an index of solubility lower than at least that of the component transferred from the inner layer  44  to the outer layer  42  and that of the component transferred from the outer layer  42  to the inner layer. This prevents denaturation of the inner layer  44  or outer layer  42  caused by the transfer of plasticizer, and prevents degradation of the characteristics of the take-out roller  4 .  
      As described above, according to this embodiment, by the denaturing the inner layer  44  of the take-out roller  4 , the outer surface of the outer layer  42  stably contacts the surface of the paper sheet P as shown in  FIG. 6 , and a sufficient frictional force can be acted on the paper sheet. This stabilizes the taking out of paper sheet P, and extends the life of the worn take-out roller  4 . Particularly, this eliminates the necessity of increasing the contact pressure of the take-out roller  4  to the paper P in order to compensate the decrease of the frictional force caused by the wearing, and substantially eliminates the problem of feeding two or more paper sheets at a time.  
       FIG. 10  is a sectional view of the take-out roller  50  according to a second embodiment of the invention. The take-out roller  50  has a relatively hard outer layer  52  made of the same rubber as the outer layer  42  of the take-out roller  4  of the first embodiment, and has an inner layer  54  made of rubber at least softer then the outer layer  52 , inside the outer layer. As in the take-out roller  4  of the first embodiment, a barrier layer (not shown) is provided between the outer layer  52  and inner layer  54 , to prevent transfer of components such as a plasticizer. In this embodiment, the hardness of the inner layer  54  is not strictly limited.  
      The take-out roller  50  of this embodiment is characterized by a circular groove  56  (remover) formed in the inner layer. Namely, the circular groove  56  concentric with the rotational axis is formed by partially eliminating both end-faces in the axial direction of the inner layer  54  softer than the outer layer  52 . When the outer surface of the outer layer  52  contacts the paper sheet P is supplied to the take-out position in a state being inclined, the groove  56  functions to positively deform the inner layer  54  at the position of the groove  56 , and to bring the outer surface of the outer layer  52  into contact with the surface of the paper sheet P stably and in a relatively wide area. The depth and width of the groove  56  determine the softness of the inner layer  54 , and can be set to the values to achieve desired softness. The shape of the groove  56  is not limited to circular, and can be optionally changed according to the desired softness of the inner layer  54 .  
      However, in the take-out roller  50  of this embodiment, when the outer surface of the outer layer  52  contacts the surface of the inclined paper sheet P, the deforming stress is concentrated on the position of the groove  56  of the inner layer  54 , and the inner layer  54  may be broken at the position of the groove  56 . Thus, as shown in  FIG. 10 , the cross section of the groove  56  is desirably wide at the bottom, and desirably curved like an arc. By forming the cross section of the bottom of the groove like an arc, the concentrated stress can be dispersed, and the breakage of the inner layer  54  in the groove  56  can be prevented.  
      To increase the fatigue strength of the inner layer  54  where the groove  56  is formed, the inner layer  54  may be made of rubber material with much carbon black added to natural rubber. This can increase the fatigue strength of the inner layer  54  and prevent the breakage of the inner layer, even if the groove  56  is formed in the inner layer. If the outer layer  52  is made of rubber material with carbon black added, a black mark may be formed on the surface of the paper sheet P when touched by the take-out roller  50 . However, it is no problem to add carbon black to the rubber material of the inner layer  54 , which does not come in contact with the paper sheet P.  
       FIG. 11  shows a modification of the take-out roller  50 . This take-out roller  50 ′ has the same structure as the take-out roller  50  of the second embodiment, except that the outer layer and inner layer are made of the same rubber material. When the outer layer and inner layer are made of the same material, the rubber material is selected by giving priority to the hardness of the outer layer and the coefficient of kinetic friction of the outer surface of the roller to the paper sheet P. Therefore, it is necessary to make the depth and width of the groove  56  relatively large to deform the roller following the state of the paper sheet P. Concretely, this embodiment uses rubber material of JIS-A with the hardness of 35-90 Ha.  
       FIG. 11  shows the state that one groove  56  is formed at the end-face of the axial direction of the roller. It is permitted to form a plurality of grooves substantially concentrically at each end-face. In any case, by setting the depth, width, shape and number of the groove  56  to appropriate values, the softness of the roller capable of following the state of the paper sheet P can be achieved. As in this modification, by forming the roller by using one kind of rubber material, the above-mentioned barrier layer becomes unnecessary. When manufacturing the take-out rollers  50  and  50 ′ of this embodiment, especially when forming the groove  56 , molding is possible without any problem. This is advantageous in the reliability and cost efficiency.  
      As described above, in the second embodiment, like the take-out roller  4  of the first embodiment, when the outer surface of the take-out roller  50  contacts the surface the paper sheet P supplied to the take-out position in the inclined state, the inner layer  54  is deformed at the position of the groove  56  and the outer surface of the outer layer  52  contacts the surface of the paper sheet P stably in a sufficiently wide area.  
      Next, an explanation will be given on a rubber roller  60  according to a third embodiment of the invention with reference to  FIG. 12  to  FIG. 15 . The rubber roller  60  of this embodiment can be used as the take-our roller  4  to take out the paper sheet P supplied to the take-out position in the direction of the surface crossing the stacking direction, and can also be used as the separation roller  34  of the separation unit  10  which separates the paper sheets P taken out in the stacked state into each single sheet.  
      As shown in  FIG. 12  and  FIG. 13 , the rubber roller  60  has basically the same structure as the take-out roller  4  of the first embodiment, except the slits  66  (remover) cut through the inner layer  64  in the axial direction. Particularly, an outer layer  62  of the rubber roller  60  is made of the same rubber material as the outer layer  42  of the take-out roller  4  of the first embodiment. However, the hardness of the inner layer  64  may be at least softer than the outer layer  62 , and may not be the same material as the inner layer  44  of the take-out roller  4  of the first embodiment. The same layer (not shown) as the above-mentioned barrier layer  46  is provided between the inner layer  62  and outer layer  64 , when necessary.  
      The slits  66  are formed symmetrically with respect to the rotation axis of the rubber roller  60 , and extended and arranged spirally in the direction crossing the radial direction, so that the adjacent slits  66  are at least partially overlapped in the radial direction of the roller. As a result, a relatively thin cylindrical wall  64   a  contacting the outer layer  62  is formed in the inner layer  64  of the rubber roller  60 , and relatively thin walls  64   b  with substantially the even thickness are formed between the adjacent slits  66 . In other words, the walls  64   b  are extended radially and spirally in the direction crossing the radial direction from the rotation axis of the roller to the wall  64   a.    
      As described above, by forming thin walls  64   a  and  64   b  in the inner layer  64 , the inner layer  64  is easily deformed elastically. In particular, by forming the elongated slits shaped as shown in the drawing, the walls  64   a  and  64   b  extending along substantially the periphery of the rubber roller (in the direction crossing the radial direction) can be formed, and the hardness of the rubber roller  60  along the radial direction can be made soft. Namely, a substantially bending stress, not an compression stress to press the rubber roller  60  in the radial direction, acts on the walls  64   a  and  64   b  shaped as shown in the drawing, and the roller is easily deformed elastically against the load in the radial direction. The quantity and size of the slits  66  are selectable according to a desired hardness of the inner layer  64 , and not limited to those shown in the drawing.  
      When this rubber roller  60  is used as a take-out roller, the inner layer  64  is elastically deformed by a relatively weak force as in the first and second embodiments, and the outer layer  62  of the rubber roller  60  can stably contact the paper sheet P supplied to the take-out position in the inclined state, and a sufficient frictional force is applied to the paper sheet P.  
      When the rubber roller  60  is used as the separation roller  34  of the separation unit  10 , if the paper sheet P is inserted into the nip between the feed roller  32  and separation roller  34 , the inner layer  64  is elastically deformed and absorbs the shock of the insertion. Compared with a case that the rubber roller  60  is pressed to the feed roller  32  by using a pinch, the rubber roller  60  does not jump up in the direction of separating from the feed roller  32 , and the outer surface of the outer layer  62  can stably contact the surface of the paper sheet P passing through the nip.  
      Contrarily, when using a mechanism that presses the separation roller  34  (e.g., a solid rubber roller) of the separation unit  10  to the feed roller  32  by using a spring, if the paper sheet P is inserted into the nip between the feed roller  32  and separation roller  34 , the separation roller  34  jumps up in the direction of separating from the roller  32  and bounces several times. At this time, the separation roller  34  does not momentarily contact the paper sheet P passing through the nip. Namely, when stacked several paper sheets P are inserted into the nip, while the separation roller  34  is bouncing, the separation roller  34  does not impart a reverse separation torque to the second and following paper sheets, and these paper sheets are fed together with the first paper sheet, causing a double-feed.  
      Contrarily, when the rubber roller  60  of this embodiment is used as a separation roller, a mechanism to press the rubber roller  60  to the feed roller by a pinch becomes unnecessary, and even if stacked several paper sheets P are inserted into the nip, the inner layer  64  is deformed and absorbs the shock of the insertion, as described above, the periphery of the outer layer  62  stably contacts the second and following paper sheets P, and a reverse separation torque is stably imparted to the second and following paper sheets P. Namely, by using the rubber roller  60  of this embodiment, the probability of doubly feeding the paper sheet P can be drastically decreased.  
      In particular, by setting in an appropriate direction, the rubber roller  60  of this embodiment can be used as a separation roller, and increases the paper sheet P feeding performance and the paper sheet P separation performance. Concretely, the roller  60  is provided in the take-out apparatus  1  at the position to rotate in the direction of the arrow e (the position shown in  FIGS. 12 and 13 ) when the paper sheet P is fed in the direction indicated by the arrow in  FIG. 13  (in the left-hand direction).  
      Namely, by providing the rubber roller  60  in this position, when the roller rotates in the direction of the arrow e and the paper sheet P runs in the direction of the arrow, a frictional force f of the paper sheet P acts on the outer surface of the outer layer  62 , as shown in  FIG. 13 . At this time, a resultant force h of the frictional force f and a reaction force g of the paper sheet P to the pressing force of the rubber roller  60  acts on the inner layer  64  of the rubber roller  60 , as shown in the drawing. Namely, in this state, the resultant force h acts as a bending stress on the walls  64   a  and  64   b  of the inner layer  64 , and the inner layer  64  is largely deformed by a relatively small force. Therefore, the shock of the insertion of the paper sheet P is absorbed, and the surface of the outer layer  62  contacts the paper sheet P stably in a sufficiently wide area.  
      Further, as shown in  FIG. 12 , when separating a second paper sheet P 2  taken out together with a first paper sheet P 1 , the rubber roller  60  rotates as a separation roller in the direction of the arrow a (in the reverse direction) to impart a separation torque. In this time, the rubber roller  60  applies a frictional force b to the second paper sheet P 2 , and the resultant force d of the friction force and the reaction force c to the pressing force of the rubber roller  60  acts on the inner layer  64  as shown in the drawing. Namely, in this state, the resultant force d acts on the wall  64   b  of the inner layer  64  along the direction of the length, a compression stress acts on the wall  64   b , and the degree of the deformation of the inner layer  64  is decreased. In other words, when imparting a separation torque to the paper sheet P by using the rubber roller  60  incorporated in the position mentioned above, the deformation amount of the rubber roller  60  is small, and a sufficiently large separation torque can be imparted to the paper sheet P.  
      As described hereinbefore, according to the embodiment, particularly when the rubber roller  60  is used as a separation roller, the shock of the insertion of the paper sheet P can be effectively absorbed, the rubber roller  60  can stably contact the paper sheet P, the probability of doubly feeding a paper sheet can be decreased, a sufficiently large separation torque can be imparted to the paper sheet P supplied in the stacked state, and the separation function can be increased. These effects can be realized by providing the rubber roller  60  in an appropriate direction. In other words, if the rubber roller  60  is reversely attached, large effects cannot be expected.  
      Further, by adopting the rubber roller of this embodiment as a separation roller, a pinch-press mechanism by a spring becomes unnecessary, the rubber roller  60  can be fixedly placed to the feed roller  32 , the apparatus structure is simplified, the apparatus is made compact, and the manufacturing cost of the apparatus is decreased.  
       FIG. 14  shows a first modification of the rubber roller  60  according to the third embodiment. A rubber roller  70  according to the first modification has the same structure as the rubber roller  60  of the third embodiment, except that the inner layer and outer layer are made of the same rubber material as one unit.  
      The rubber roller  70  provides the same functions and effects as those of the rubber roller  60 . In the rubber roller  70 , it is necessary to set the coefficient of kinetic friction of the outer surface to contact the paper sheet P to an appropriate value, if a rubber material with a relatively large coefficient of kinetic friction is selected, the roller becomes difficult to deform compared with the rubber roller  60 . Therefore, it is necessary to adjust the thickness of the wall by adjusting the size of the slit  72  in order to obtain a desired deformation rate.  
       FIG. 15  shows a rubber roller  80  according to a second modification. The rubber roller  80  according to the second modification has basically the same structure as the rubber roller  60 , and has many auxiliary holes  88  to even the deformation of the inner layer, in addition to slits  86 . The shape, quantity, position and size of the slit provided in the inner layer can be optionally changed as long as they can apply a desired deformation ratio to the rubber roller.  
      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, the take-out rollers  4 ,  50  and  50 ′ of the first and second embodiment may be adopted as the separation roller  34  of the separation unit  10 . Namely, the rubber roller of the invention has the characteristic structure deformable according to the state of the paper sheet P. Therefore, the rubber roller can effectively absorb the shock of the insertion of a paper sheet, even if it is used as a separation roller.  
      In the embodiments described hereinbefore, the rubber roller is composed of two layers, outer and inner layers, but the number of layers is not limited to two. A rubber roller having three or more layers including an outer layer is allowed. In this case, a barrier layer may be provided among the layers if necessary.