Patent Publication Number: US-2011048208-A1

Title: Drive mechanism

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The present invention relates to a drive mechanism and particularly, but not exclusively to a drive mechanism for a hole punch. 
     2. Description of the Prior Art 
     U.S. Patent Application Publication No. 2006/0117927 discloses a hole punch comprising a frame and a handle which is arranged to pivot with respect to the frame. The handle comprises a plurality of teeth disposed upon a pinion at a lower end thereof. The pinion is arranged to engage with a plurality of teeth disposed upon a rack, such that as the handle is pivoted with respect to the frame, the rack becomes driven by the pinion which drives a punching arm into a sheet of paper, for example. 
     However, in order to drive the rack and thus the punching arm, the handle is rotated from one side of the frame, over the frame to the other side. This movement is found to lift the hole punch and cause the hole punch to slide upon the surface on which it is placed, with the result that the hole punch can move with respect to the sheet of paper. Accordingly, it is difficult to stabilize the punch while maintaining the correct alignment of the sheet. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of the present invention there is provided a drive mechanism for a hole punch, the mechanism comprising a frame and a lever comprising a first end and a second end, the lever being pivotally coupled to the frame at a pivot point disposed intermediate the first and second end thereof,
         the frame comprising a lever engaging portion for engaging with a frame engaging portion disposed at the second end of the lever, wherein,   as the first end of the lever is pivoted about the pivot point, the frame engaging portion is arranged to move along the lever engaging portion to cause the pivot point to move with respect to the frame.       

     The movement of the pivot point with respect to the frame only requires the handle to move through a small angular range in order to provide the required travel on the punching arm. The lever thus remains at one side of the frame throughout its range of motion. 
     The pivot point is preferably arranged to move along a channel which extends substantially parallel to the lever engaging portion. 
     Preferably, the lever engaging portion comprises a first plurality of formations and the frame engaging portion comprises a second plurality of formations. The first and second plurality of formations preferably provide a fulcrum for the lever, which is arranged to move along the lever and frame engaging portions. Preferably, the first and second plurality of formations are complimentary formations. 
     The lever engaging portion preferably comprises a substantially linear arrangement of first formations. The frame engaging portion preferably comprises a substantially arcuate arrangement of second formations. 
     Preferably, the distance between the pivot point and the first end of the lever is greater than the distance between the pivot point and the second end of the lever. This provides the required mechanical advantage for the user in punching a hole in, for example, a number of sheets of paper simultaneously. 
     The drive mechanism preferably further comprises a punching arm which is arranged to move with the pivot point and which is arranged to punch a hole in a sheet of paper, for example. 
     The first end of the lever is preferably disposed to one side of the pivot point with respect to the frame and preferably remains at the one side throughout the range of motion of the lever. 
     Preferably, the frame comprises a slot for receiving material in which it is intended to punch a hole. The lever is preferably pivotable between a first configuration in which the punching arm is removed from the slot and a second configuration in which the punching arm extends within the slot. 
     In accordance with a second aspect of the present invention there is provided a hole punch comprising the drive mechanism of the first aspect. 
     Other objects and features of the present invention will become apparent when considered in combination with the accompanying drawing figures which illustrate certain preferred embodiments of the present invention. It should, however, be noted that the accompanying drawing figures are intended to illustrate only certain embodiments of the claimed invention and are not intended as a means for defining the limits and scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       In the drawing, wherein similar reference numerals and symbols denote similar features throughout the several views: 
         FIG. 1   a  is perspective view of a drive mechanism according to an embodiment of the present invention, in a first configuration; 
         FIG. 1   b  is perspective view of a drive mechanism of  FIG. 1   a , in a second configuration; 
         FIG. 2   a  is a side view of the drive mechanism of  FIG. 1   a;    
         FIG. 2   b  is a side view of the drive mechanism of  FIG. 1   b ; and 
         FIG. 3  is an exploded view of a hole punch comprising the drive mechanism of  FIG. 1  or  2 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWING FIGURES AND PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 to 3  of the drawings, there is illustrated a drive mechanism  10  for a hole punch  100  according to an embodiment of the present invention. The drive mechanism  10  comprises a frame  11  and a handle  12  pivotally mounted with respect to the frame  11 . The frame  11  comprises a base  13  that is substantially C-shaped in longitudinal cross-section (as illustrated in  FIG. 2 ) and comprises an upper, substantially planar base level  13   a  and a lower, substantially planar base level  13   b . The frame  11  further comprises a pair of substantially planar support pillars  14  which extend from the upper base level  13   a , in a direction substantially perpendicularly thereto. 
     The support pillars  14  are disposed upon the base  13 , either side of a longitudinal axis thereof and are orientated substantially parallel to each other and the longitudinal axis, such that the frame  11  is substantially symmetric about the longitudinal axis. Each pillar  14  comprises an elongate channel  15  which extends through the pillar  14 , along a length of the pillar  14 , and a flange  16  which extends along the length of the pillar  14  at a forward edge  14   a  thereof. Each flange  16  is turned outwardly away from the longitudinal axis and extends in a direction substantially parallel to the channel  15  formed in the adjacent pillar  14 . In the embodiment illustrated, each flange  16  and channel  15  extend substantially perpendicularly to the upper level  13   a  of the base  13 . 
     The drive mechanism  10  further comprises a pivot rod  17  which extends between each pillar  14  and through each elongate channel  15 . The pivot rod  17  is prevented from moving out from the elongate channel  15  within the support pillars  14 , by a pair of C-shaped clips  18  one of which is arranged to pass over the rod  17  at the side of each pillar  14  that is opposite the side proximate to the longitudinal axis. 
     The free ends  17   a ,  17   b  of the rod  17  separately comprise a drive plate  19  having an aperture  19   a  disposed at one end thereof for receiving a free end of the rod  17  and a substantially arcuate edge  19   b  disposed at the opposite end thereof. The arcuate edge  19   b  of each drive plate  19  comprises a plurality of teeth  20  which are arranged to separately engage between a plurality of teeth  21  disposed on a rear facing portion of each flange  16 . The teeth  21  disposed on each flange  16  are of substantially complimentary size and shape to the teeth  20  formed on the drive plates  19  and extend along the length of the flange  16 . The pivot rod  17  is substantially square in cross-section and the aperture  19   a  formed in each drive plate  19  is of similar size and shape to the cross-section of the pivot rod  17  such that as the pivot rod  17  rotates within the channel  15 , the drive plate  19  is caused to rotate. The interlocking teeth  20 ,  21  provide a fulcrum for the handle  12 , such that as the handle  12  is pivoted with respect to the frame  11 , the fulcrum travels along the respective flange  16  causing the pivot rod  17  to move along the channels  15 . 
     The handle  12  is substantially U-shaped and arranged to extend to either end  17   a ,  17   b  of the pivot rod  17 . Each end of the handle  12  is separately coupled to one end of the pivot rod  17  by a locking plate  22 . The locking plates  22  are housed within a depression  23  formed at each end of the handle  12  and comprise a substantially square aperture  22   a  for receiving a free end  17   a ,  17   b  of the rod  17 . The depressions  23  are of substantially complimentary shape and size to the locking plates  22  and thus prevent any rotation of the plate  22  with respect to the handle  12 . The plates  22  further comprise a barb  22   b  which is arranged to locate within a locking recess  23   a  formed within the depression  23  and thus further serve to prevent any rotation of the plate  22  with respect to the handle  12 . The barbs  22   b  on the locking plates  22  and the depressions  23  formed within the handle  12  thus lock the rotation of the pivot rod  17  to the handle  12  such that as the handle  12  is pivoted with respect to the frame  11 , the pivot rod  17  is caused to rotate within the channels  15 . 
     The drive mechanism  10  further comprises a mounting  24  for one or more punching arms  25  which are arranged to punch a hole in a sheet of paper, or metal (not shown), for example. The mounting  24  is disposed between the pillars  14  and comprises a plate  26  having a pair of eyelets  27  disposed on an upper side thereof for receiving the pivot rod  17 . The one or more punching arms  25  extend from the underside of the plate  26  and are arranged to extend through aligned apertures (not shown) formed in the upper and lower levels  13   a ,  13   b  of the base  13  of the frame  11 . The eyelets  27  comprise a substantially cylindrical internal passage and an internal collar  28  disposed therein, which is arranged to rotate within the respective passage. Each collar  28  comprises a substantially cylindrical outer surface and an inner aperture that is substantially square in cross-section, and is rigidly coupled to the respective drive plate  19  so that the inner aperture of each collar  28  is substantially aligned with the respective aperture  19   a  in the drive plate  19 . The collars  28  are arranged to receive the pivot rod  17  and enable the rod  17  to freely rotate within the respective eyelet  27  without causing any rotation of the mounting  24 . 
     Referring to  FIG. 3  of the drawings, there is illustrated an exploded view of a hole punch  100  comprising the drive mechanism  10  illustrated in  FIGS. 1 and 2 . The lower level  13   b  of the base  13  of the frame  11  of the drive mechanism  10  is removably coupled within a receptacle  110 , which serves to retain the material removed during the punching process. The pillars  14  and mounting  24  are housed within a shroud  120  which is removably coupled to an upper level  13   a  of the frame base  13 . 
     In use, the material, for example sheets of paper or metal (not shown) or similar that requires a hole or holes to be punched therein, is placed within the base  13  of the frame  11  between the upper  13   a  and lower levels  13   b  thereof and suitably aligned with respect to the punching arms  25 . The handle  12  is then pivoted from an orientation in which it extends over a rear of the base  13  at an acute angle thereto, toward the base  13 . As the handle  12  is pivoted downwardly, the pivot rod  17  is rotated with respect to the frame  11  and the drive plates  19  are caused to travel from an upper region of the respective flanges  16  toward the base  13 . During this motion of the handle  12 , the pivot rod  17  moves along the channels  15  in the pillars  14  and thus advances the mounting  24  toward the base  13 . The force subjected to the handle  12  is principally directed downward toward the base  13  of the hole punch  100  and thus toward the surface (not shown) upon which the hole punch  100  is placed. This ensures that the hole punch  100  remains substantially stationary as the handle  12  is pivoted. 
     As the mounting  24  is moved toward the base  13 , the punching arms  25  move into the space between the upper and lower levels  13   a ,  13   b  of the base  13  and thus into the material (not shown). The pivot rod  17  is coupled to the handle  12  at a position such that the distance between the pivot rod  17  and the arcuate edge  19   b  of the drive plate  19  is less that the distance between the pivot rod  17  and the distal end  12   a  of the handle  12 . This provides the operator (not shown) with a mechanical advantage which enables the operator (not shown) to punch through several sheets of paper (not shown) simultaneously for example, or a particularly thick sheet of paper, for example, with minimal downward force. 
     The punching arms  25  are arranged to pass through the aligned apertures (not shown) in the upper and lower levels  13   a ,  13   b  of the base  13  such that the material removed during the punching process becomes ejected into the receptacle  110 . Upon releasing the handle  12 , a coil spring (not shown) causes the handle  12  and thus the mounting  24  to return to their initial orientation. As the mounting  24  returns to its initial position the punching arms  24  become removed from between the upper and lower levels  13   a ,  13   b  of the base  13 , and thus the material, so that the material can be removed from the punch. 
     While the drive mechanism  10  of the present invention has been exemplified through its incorporation in a hole punch  100 , it is envisaged that the mechanism  10  would also find suitable application in cutting devices (not shown), for example. From the foregoing therefore, it is evident that the drive mechanism of the present invention provides for a simple yet effective means of driving a cutting blade or punching arm into a material. 
     While only several embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that many modifications may be made to the present invention without departing from the spirit and scope thereof.