Patent Publication Number: US-7721635-B2

Title: Lever handled paper punch

Description:
FIELD OF THE INVENTION 
     The present invention relates to a punch apparatus having a lever handle for punching holes in a stack of paper sheets. 
     BACKGROUND OF THE INVENTION 
     Prior art paper punches typically use a direct force approach to punch holes in a stack of paper sheets. In these prior punches, the user presses down on a pivoting cover flap which forces the punch pins down and into the paper stack. This direct force approach has very little mechanical advantage. The force required to punch through the holes increases with the thickness of the paper stack. For thicker paper stacks, the required force to punch through the stack may exceed what the user can easily provide. 
     To address this problem, several punch manufacturers have proposed using a lever mechanism to reduce the required force by increasing the mechanical advantage. For example, U.S. Pat. No. 5,778,750 proposes the use of an elongated lever handle where one end of the handle is pivotally fixed to the punch and the other end is pressed down by the user. In turn, an intermediate surface (between the ends of the handle) is forced down on the cover flap to exert the punching force. In U.S. Pat. No. 6,109,155, a lever handle is pivotally attached to a rod extending up from the based and through the cover flap. As in the &#39;750 patent, when the handle is pressed down by the user, an intermediate surface on the lever presses down on the cover flap to exert the punching force. Both of these patents disclose the use of a lever handle to increase the force applied to the cover flap by mechanical advantage. This effectively reduces the maximum force the user needs to apply to punch the paper stack. 
     The present invention offers a novel lever-handled paper punch which increases the mechanical advantage in a different manner than other proposed lever punches. The present punch reduces the maximum punch force and improves upon the disadvantages of prior art punches. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a punch apparatus for punching holes through a paper stack. The apparatus has a punch base with an attached mounting plate. Punch pins are mounted to the mounting plate for punching through the paper stack. A lever handle is rotationally attached to the mounting plate. The lever handle has a handle end, a contact end, and a rotation axis between the handle end and the contact end. A main shaft is rotationally mounted on the punch base. A lever arm and pressure plate are attached to the main shaft. The lever arm engages the contact end of the lever handle while the pressure plate engages the punch pins. When a downward force is applied to the handle end of the lever handle, the lever handle rotates about the rotation axis. The contact end of the lever handle then exerts an upward force on the lever arm which in turn rotates the main shaft and attached pressure plate. As a result, the pressure plate exerts a punching force down on the punch pins thereby causing the punch pins to punch down through the paper stack. 
     Other aspects of the invention include that the punching force is greater than the downward force due to a mechanical advantage of the lever handle. Each punch pin may be aligned in a punch head bracket adjustably mounted to the mounting plate. Each punch head bracket preferably has a paper feed slot for positioning the paper stack. Each punch pin has a top end engaged by the pressure plate and a punch end for punching through the paper stack positioned in the paper feed slot. The punch pins are preferably spring mounted in the punch head brackets such that the punch ends are retracted above the paper feed slot when the downward force is not being applied. A cover may be mounted on the punch base for covering the mounting plate, the main shaft, the lever arm, the pressure plate, and the plural punch head brackets. Preferably, the cover does not move during operation of the punch apparatus. The contact end of the lever handle is preferably a cylindrically-shaped transverse pin. The lever arm may have a cylindrically-shaped contact pin for engaging the contact end of the lever handle. The handle end may have a padded region. The punch base may have a chip tray for collecting paper hole cutouts punched from the paper stack. The punch base may have a window for viewing inside the chip tray. Assuming the main shaft rotates about a first axis, the punch pins move in the direction of a second axis, and the lever handle rotates about a third axis; it is preferred that the first, second and third axes be orthogonal. 
     Another embodiment of the invention is directed to a paper punch comprising a base having a substantially rectangular shape. A mounting plate is fixedly attached on the base. A main shaft is rotationally attached along a longitudinal axis of the base. The main shaft has a longitudinally attached pressure plate and a perpendicularly extending lever arm. A lever handle is rotationally attached to the mounting plate. The lever handle comprises a handle portion, a contact portion, and a rotation axis between the handle and contact portions. The rotation axis is perpendicular to the longitudinal axis. The contact portion of the lever handle is in contact with the lever arm of the main shaft. A plurality of punch units are attached to the mounting plate and are in contact with the pressure plate. When an applied force is exerted on the handle portion of the lever handle, it is transferred through the rotation axis to the contact portion which forces the lever arm to rotate the main shaft such that the pressure plate transfers a punching force to the plurality of punch units to punch holes in a stack of paper sheets. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying drawings where: 
         FIG. 1  is a back perspective view of an embodiment of the lever-handled punch; 
         FIG. 2  is a front perspective view of an embodiment of the lever-handled punch; 
         FIG. 3  is a back perspective view of an embodiment of the lever-handled punch with the cover attached; 
         FIG. 4  is a back view of an embodiment of the lever-handled punch; 
         FIG. 5  is a top view of an embodiment of the lever-handled punch with the cover attached; 
         FIG. 6  is a front view of an embodiment of the lever-handled punch with the cover attached; and 
         FIG. 7  is a side view of an embodiment of the lever-handled punch with the cover attached. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention uses a lever handle on a paper punch in a novel manner for increased mechanical advantage. The lever handle effectively reduces the amount of force required from the user to punch holes in a stack of paper sheets. 
       FIG. 1  is a back perspective view of an embodiment of the lever-handled punch. The punch comprises a base  100  with a mounting plate  160  and left and right side vertical support plates  150 . The plates may be attached to the base with rivets or any other suitable attachment means. A lever handle  110  is mounted at an axis point  112  to the mounting plate  160  by a pivot screw. A removable side support  113  may be attached to relieve stress on the pivot screw. Note, the lever handle  110  does not contact the base  100 . The lever handle  110  has a handle end  114  which is pressed down upon by the user and a contact end  116  which transfers a force to the punch. The handle end  114  may have a soft padding material. The contact end  116  of the handle is preferably a cylindrically-shaped transverse pin. The upper surface of the contact end  116  contacts the under surface of contact lever arm  130 . The mounting plate  160  has a number of slotted holes for mounting and adjusting the spacing of the punch pins using set screws  190 . The punch base  100  has a chip tray  170  (bottom cover) for collecting the paper hole cutouts (chips). The chip tray  170  is preferably made of a non-marking, non-skid, semi-pliable material. The punch base may have windows  180  (portals) for viewing inside the chip tray to determine when the punched paper holes need to be emptied. 
       FIG. 2  is a front perspective view of an embodiment of the lever-handled punch.  FIG. 2  shows that contact lever arm  130  is attached at an end of main shaft  240 . Pressure plates  250  are mounted to the main shaft, with rivets or any other suitable attachment means. The main shaft is mounted at each end through the left and right side vertical support plates  150  to allow for rotation about its longitudinal axis. A number of punch head brackets  200  are adjustably mounted to the mounting plate  160 . Each punch head bracket has a paper feed slot  222  where the paper stack is inserted for punching. Each punch head bracket contains a vertically aligned punch pin  210  which is bias mounted using a spring  220  such that the punch end of the punch pin is retracted above the paper feed slot when no punching force is being applied to the pin. A removable cover  320  (not shown) is attached using cover mounting lock pins  230  on the left and right side vertical support plates. 
     The present punch is operated by inserting a stack of paper sheets into the paper feed slots  222 . The user presses down upon the handle end  114  of the lever handle. By virtue of pivot screw  112 , the downward force on the handle end  114  is translated into a leveraged upward force on the contact end  116 . The amount of leverage is related to the ratio of the distances between the handle end and the pivot screw and the pivot screw and the contact end. The contact end forces the contact lever arm  130  upward. This upward force is translated through contact lever arm  130  into a rotational force on the main shaft  240 . The rotation of the main shaft about its longitudinal axis forces the pressure plates  250  down onto the top ends of the punch pins  210 . The punch ends of the pins are driven downward through the paper feed slot to punch through any inserted paper sheets. The paper hole cutouts created by the punching operation drop through slot openings  224  in the base and into the chip tray. When the user stops pressing on the handle, the spring biased punch pins retract up into the punch brackets to clear the paper feed slot so that the punched paper stack can be removed. 
       FIG. 3  is a front perspective view of an embodiment of the lever-handled punch with the removable cover  320  attached. The cover preferably attaches to the left and right side vertical support plates  150 . The cover does not contact the lever arm and does not move during operation of the punch. 
       FIG. 4  is a back view,  FIG. 5  is a top view,  FIG. 6  is a front view, and  FIG. 7  is a side view of an embodiment of the lever-handled punch with the cover attached.  FIGS. 4-7  show the position of the cover relative to the other punch components. 
     The invention has been described in the context of a three-hole paper punch. The invention, however, can be extended to punches having other numbers of holes and for use in punching materials other than paper. The invention should be construed to include any useful equivalents. Such equivalents will be understood to be within the scope of the invention, which is defined by the appended claims and equivalents.