Patent Publication Number: US-2006017213-A1

Title: Paper feeding device

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a paper feeding device with a pickup roller that feeds a sheet of paper in a printer or a copying machine.  
      2. Description of the Background Art  
      In a printer or a copying machine, a pickup roller is used to feed a sheet of paper. In a commonly used pickup roller, the surface thereof is formed of an elastic and anti-slip material such as rubber. The pickup roller is rotated to feed a sheet of paper. The surface of the pickup roller formed of rubber and the like gradually wears by the repeated operation of paper feeding. Therefore, the pickup roller needs to be replaced regularly.  
      The pickup roller is rotary driven by a rotational axis. If the rotational axis is provided so as to penetrate the pickup roller, the rotational axis itself needs to be detached when the pickup roller is to be replaced. An end of the rotational axis is provided with means for transmitting driving force of a gear or a pulley to drive the rotational axis. Accordingly, it is not easy to detach the rotational axis that retains the pickup roller.  
      Thus, a structure that allows the pickup roller to be replaced without detaching the rotational axis is proposed. In the structure shown in  FIG. 7  and described in Japanese Patent Laying-Open No. 10-236673, a pair of collars  72  is provided that is penetrated by a rotational axis  71 . The surface of collars  72  facing a pickup roller body  74  is provided with a rectangular axial member  73  and the corresponding part of pickup roller body  74  is provided with a rectangular concave portion  75 . When pickup roller body  74  is to be replaced, one of the pair of collars  72  is shifted axially and the pickup roller body is also shifted in the same direction. Thus, rectangular axial member  73  is disengaged from concave portion  75  so that fixation of pickup roller body  74  is released. Thus, pickup roller body  74  can be replaced without detaching rotational axis  71 .  
      In the structure shown in  FIG. 8  and described in Japanese Patent Laying-Open No. 04-075934, rotational axis  81  is provided with a pair of rectangular holes  85  and a pair of round holes  86 . Pickup roller  82  is provided with a pair of engaging pieces  83  and a pair of positioning pins  84  at respective corresponding positions.  
      When pickup roller  82  is to be mounted, positioning pin  84  of pickup roller  82  is inserted into round hole  86  to position pickup roller  82 . By the insertion, engaging piece  83  engages with rotational axis  81  so that pickup roller  82  is fixed to rotational axis  81 . For a removing operation, pickup roller  82  can be removed by pulling pickup roller  82  to pull out positioning pin  84  while releasing engagement of pair of engaging pieces  83 .  
      In the mounting structure of the pickup roller described in Japanese Patent Laying-Open No. 10-236673, there is a problem of increase in the number of parts since the pickup roller is formed of three parts, i.e. pickup roller body  74  and the pair of collars  72  provided at opposite sides thereof. Further, there is also a problem of increase in the number of manufacturing processes, since the pair of collars  72  needs to be mounted to rotational axis  71  and then pickup roller  74  needs to be mounted to the mounted pair of collars  72  when manufacturing a printer and the like.  
      In the mounting structure of the pickup roller described in Japanese Patent Laying-Open No. 04-075934, there is a problem of difficulty of operation and reduced working efficiency since both of positioning pins  84  must penetrate respective round holes  86  of rotational axis  81  simultaneously.  
     SUMMARY OF THE INVENTION  
      An object of the present invention is to provide a paper feeding device in which detachment is easy when a pickup roller is to be replaced and that does not increase the number of parts and manufacturing processes.  
      A paper feeding device according to the present invention includes a rotational axis with a groove shaped cross section having a web extending in the longitudinal direction and a flange provided at opposite sides thereof, and a pickup roller having a concave groove to receive the rotational axis. An end of the pickup roller is provided with a pair of engaging pieces that engages with a flange end portion of the rotational axis respectively, and the other end of the pickup roller is provided with a hook that is inserted into an insertion hole provided on the web of the rotational axis.  
      Preferably, in the paper feeding device, the hook extends outwardly from the body of the pickup roller and forms a stepped shape having an abutting surface that abuts against the inner surface of the web.  
      Preferably, in the paper feeding device, a notch for positioning is provided at a site in the flange end portion where the engaging piece engages.  
      Further, preferably, in the paper feeding device, the engaging piece of the pickup roller is formed of resin and an end of the engaging piece is made to engage with the flange end portion by elasticity of resin.  
      In the paper feeding device of the present invention, detachment is easy when the pickup roller is to be replaced and there is no increase in the number of parts and manufacturing processes.  
      The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view from one end of a pickup roller in an embodiment according to the present invention.  
       FIG. 2  is a perspective view from the other end of the pickup roller in an embodiment according to the present invention.  
       FIG. 3  is a front view of a rotational axis in an embodiment according to the present invention.  
       FIG. 4  is a front view showing a process in which the pickup roller is attached to the rotational axis.  
       FIG. 5  is a front view showing a state in which the pickup roller has been attached to the rotational axis.  
       FIG. 6  shows the pickup roller in a used state in an embodiment according to the present invention.  
       FIG. 7  is a perspective view of a mounting structure of the pickup roller in the prior art.  
       FIG. 8  is a perspective view of the mounting structure of the pickup roller in the prior art. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      A paper feeding device in one embodiment of the present invention now will be described referring to  FIGS. 1-6 .  
      A paper feeding device of the present embodiment includes a rotational axis  41  with a groove shaped cross section, and having a web  41   w  extending in the longitudinal direction and a flange  41   f  provided at opposite sides thereof. The paper feeding device further includes a pickup roller  1  having a concave groove  25  to receive rotational axis  41 . One end of pickup roller  1  is provided with a pair of engaging pieces  21  that engages with an end portion of flange  41   f  of pickup roller  1  respectively, and the other end of pickup roller  1  is provided with a hook  15  that is inserted into an insertion hole  43  provided on web  41   w  of rotational axis  41 . Hook  15  extends outwardly from a pickup roller body  11  and has a stepped shape having an abutting surface  15   a  that abuts against the inner surface of web  41   w.  A notch  45  for positioning is provided at a site in an end portion of flange  41   f  where engaging piece  21  engages. Engaging piece  21  of pickup roller  1  is formed of resin so that an end of engaging piece  21  is made to engage with notch  45  of the end portion of flange  41   f  by elasticity of resin.  
      Pickup roller  1  is formed of a body  11  of pickup roller of synthetic resin, and a non-slip material  31  of rubber provided on the perimeter thereof. Non-slip material  31  occupies about two-thirds of the area of the perimeter surface of pickup roller body  11 . As shown in  FIG. 6 , non-slip material  31  is pressed against the surface of a sheet  53  of paper and sends out sheet  53  in the paper feeding direction when pickup roller  1  is rotated. Thus, a material that has a certain degree of elasticity as well as frictional force with respect to a sheet of paper is selected.  
      Pickup roller body  11  serves to retain non-slip material  31  and is fixed to rotational axis  41 . Pickup roller body  11  is provided with concave groove  25  extending to the center of pickup roller body  11 . Concave groove  25  also extends in the longitudinal direction (the axial direction) of pickup roller body  11  and is exposed at the opposite sides thereof as shown in  FIGS. 1 and 2 .  
      One end of pickup roller body  11  is provided with pair of engaging pieces  21 . As shown in  FIG. 1 , engaging pieces  21  are formed as a cantilever that are pendent downwardly from opposite sides of a base portion  22  protruding horizontally from an end surface of pickup roller body  11 . As shown in  FIG. 1 , the end portion of engaging piece  21  has a crochet hook shape and the end portion engages with the end portion of flange  41   f  of rotational axis  41  from the outside. Pickup roller body  11  and engaging piece  21  are formed of synthetic resin so that the end portion of engaging piece  21  can be made to engage with flange  41   f  of rotational axis  41  by elasticity of resin.  
      The other end of pickup roller body  11  is provided with hook  15 , as shown in  FIG. 2 . Hook  15  is formed to have a stepped shape protruding outwardly from pickup roller body  11 . With pickup roller body  11  mounted to rotational axis  41 , the upper surface of an end portion of hook  15  forms an abutting surface  15   a  that abuts against the inner surface of web  41   w  of rotational axis  41 .  
      Rotational axis  41  shown in  FIG. 3  is made of metal and includes web  41   w  and flange  41   f  provided at opposite sides thereof and has a groove shaped cross section. A paper feeding cam  47  formed of synthetic resin is provided at opposite ends of rotational axis  41 . Near the center of rotational axis  41  is provided an insertion hole  43  into which hook  15  of pickup roller body  11  is inserted. Insertion hole  43  is formed as a rectangular hole provided on web  41   w.  Further, at a position in the end of flange  41   f  away from insertion hole  43  by a predetermined distance is provided a notch  45  where engaging piece  21  of pickup roller  1  engages to determine an engaging position of engaging piece  21 .  
      Then, a procedure to mount pickup roller  1  to rotational axis  41  will be described. First, as shown in  FIG. 4 , hook  15  of pickup roller  1  is inserted into insertion hole  43  of rotational axis  41 . Next, mounting of pickup roller  1  is completed by pressing down the opposite side of pickup roller  1  to engage engaging piece  21  with notch  45  of the end of flange  41   f  from the outside. Thus, in the pickup roller  1  of the present embodiment, pickup roller  1  can be mounted very easily.  
      In the mounting structure of the pickup roller described in Japanese Patent Laying-Open No. 04-075934, it is necessary to insert a pair of positioning pins into the rotational axis simultaneously, rendering positioning very difficult. However, in pickup roller  1  of the present embodiment, hook  15  is latched into rotational axis  41  and then engaging piece  21  of the opposite side is engaged so that the positioning is completed by just inserting hook  15  into insertion hole  43 . Thus, pickup roller  1  can be mounted to rotational axis  41  very easily. This effect is evident in the process where pickup roller  1  is replaced as well as in the process where pickup roller  1  is mounted to rotational axis  41  in manufacturing a printer and the like.  
      Further, rotational axis  41  is provided with notch  45  where engaging piece  21  engages so that pickup roller  1  can be positioned more securely. More specifically, as shown in  FIG. 4 , in pickup roller  1  of the present embodiment, hook  15  is inserted into insertion hole  43  from an oblique direction. Accordingly, insertion hole  43  needs to have some play. The end portion of engaging piece  21  of pickup roller  1  and notch  45  are formed to exactly fit together so that backlash of pickup roller  1  after installing can be eliminated. It is to be noted that notch  45  may be omitted and engaging piece  21  may directly engage with the end of flange  41   f  of rotational axis  41  if backlash of pickup roller  1  after installing is not considered as a serious problem.  
      When pickup roller  1  is to be removed, first the side of engaging piece  21  is pulled upwardly. At this stage, the engagement can be easily released since engaging piece  21  engages through elasticity of resin. Then, hook  15  is pulled out from insertion hole  43  to complete the removal. Thus, pickup roller  1  can be removed very easily, too.  
      Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.