Abstract:
A hand operated stapling tool, which uses the energy stored in a spring to install staples by an impact blow, is disclosed. A housing body is preferably cast or molded. A handle is pivotally attached to the rear end of the housing body, pressing down the handle stores energy in a power spring by bending the middle section of the power spring, and further pressing down the handle unlocks the front end of the power spring which forces a driving blade to move downward and expels a staple out of the bottom of the housing body. A staple feeding track is formed at the bottom of the housing body, and the stored staples are secured by a rear-hinged panel.

Description:
CROSS-REFERENCES 
   U.S. Patent Documents 
   
     
       
             
             
             
             
             
           
         
             
                 
             
           
           
             
               2,326,540 
               8/1943 
                 
               Krantz 
                1/49 
             
             
               2,671,215 
               3/1954 
                 
               Abrams 
                1/49 
             
             
               2,769,174 
               11/1956 
                 
               Libert 
                1/49 
             
             
               3,862,712 
               1/1975 
                 
               LaPointe et al. 
               227/127 
             
             
               4,119,258 
               10/1978 
                 
               Ewig, Jr 
               227/132 
             
             
               5,765,742 
               6/1998 
                 
               Marks 
               227/132 
             
             
               5,988,478 
               11/1999 
                 
               Marks 
               227/132 
             
             
               6,918,525 
               7/2005 
                 
               Marks 
               227/120 
             
             
                 
             
           
        
       
     
   
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to hand-operated fastener applying devices and specifically to spring-powered staplers. 
   2. Description of the Related Art 
   Various spring-powered staplers employs basically the same operating principle that is to use a spring to store energy, which is then released to drive a blade to expel a staple out of the bottom of the stapler. The stapler of the present invention also uses this operating principle, but makes the structure more simplified, compact and flexible. 
   U.S. Pat. No. 2,326,540 issued to Krantz discloses a staple gun in which a hand lever is pivoted at the back and an actuating lever engages a vertically positioned spring and driving assembly, hence Krantz&#39;s staple gun is quite bulky. 
   U.S. Pat. No. 2,671,215 issued to Abrams discloses a staple gun with similar vertically placed spring and driving assembly, but a different actuating means. 
   U.S. Pat. No. 2,769,174 issued to Libert discloses a staple gun in which an actuating means employs two linked levers and spring and driving member assembly vertically positioned. 
   U.S. Pat. No. 3,862,712 issued to LaPointe et al. discloses a staple gun with a staple feeding track that slides rearward to expose a staple loading chamber. A releasable latch assembly retains the track in position. 
   U.S. Pat. No. 4,119,258 issued to Ewig, Jr. discloses a staple gun with a body and hand lever constructed substantially of plastic material. Its hand lever is pivoted in the front and its spring and driving assembly is vertically positioned. 
   U.S. Pat. No. 5,988,478 issued to Marks discloses a stapling machine in which an actuating level is used to store energy in the power spring and then released it to force a plunger to move downward and expel a staple from the bottom of the stapling machine. In order to accommodate the actuating lever, the hand-operated stapling machine is less compact. 
   U.S. Pat. No. 6,918,525 issued to Marks discloses a desktop stapler in which a spring lifting level is also used to activate the stapler, hence it is less compact. 
   SUMMARY OF THE INVENTION 
   In the preferred embodiment, a housing body is preferably cast or molded, which houses a driving blade, a power spring with which the driving blade is engaged, a lock assembly, and a return spring. The movement of the driving blade is contained in a vertical channel formed in a front of the housing body. A handle is pivotally attached to a rear end of the housing body with a rod touches the middle section of the power spring. With the rear end of the power spring being supported by the housing body, and the front end of the power spring being locked with the driving blade by the lock assembly in the upper position, when pressing down the handle, its rod forces the middle section of the power spring to bend and store energy. Further pressing down the handle causes the lock assembly to unlock the driving blade. Then the biased power spring releases its energy in a downward blow along with the driving blade which expels a staple at the front end of the staple feeding track. 
   The return spring is mounted underneath the power spring in a location vertically aligned to the handle rod. When hand pressing force is removed, the return spring resets the power spring along with the driving blade back up to their locked positions. 
   A staple feeding track is formed at the bottom of the housing body, with a rear-hinged panel snaps to the side walls of the feeding track to prevent staples from falling off the feeding track during operation, and a spring biased pusher to secure the staple(s) to the front of the feeding track. 
   This compact front end gripped and front end staple exiting design of the preferred embodiment can provides the advantage of a staple applying action similar to that of a hand-pressed desktop stapler, yet simple enough to be manufactured in comparable sizes and costs. Besides, without the constraints of an lifting lever, the stapler of present invention has further advantages of scalability in size, and flexibility in exterior designs. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevational view of preferred embodiment stapler, shown in a partial sectional view, of the present invention in a resting position. 
       FIG. 2  is a side elevational view of the stapler of  FIG. 1 , just prior to ejection of a staple. 
       FIG. 3A  is a perspective view of the driving blade with two openings for linking with the power spring and a project member on top to engage the locking tongue. 
       FIG. 3B  is a perspective view of the driving blade with two openings for linking with the power spring and an opening for engaging locking tongue. 
       FIG. 3C  is a perspective view of the driving blade with a projective horizontally placed column for linking with the power spring, and an opening for engaging locking tongue. 
       FIG. 4A  is a top plan view of the lock assembly including a lock shaft with a locking tongue in the front, biasing springs on both sides and an opening on the lock shaft for handle rod to go through the lock shaft and for unlocking the driving blade with a rearward facing wedge-like surface. 
       FIG. 4B  is a side view of the lock assembly of  FIG. 4A , showing a bottom tapered front end of the locking tongue to enable the driving blade to be pushed up and to engage the locking tongue. 
       FIG. 5A  is a top plan view of the lock assembly including a lock shaft with a locking tongue in the front, a biasing spring at the back and a wedge with a slanted surface on its front side for the lock shaft being pushed backward by a second rod on the handle. 
       FIG. 5B  is a side view of the lock assembly of  FIG. 5A , showing a bottom tapered front end of the locking tongue to enable the driving blade to be pushed up and to engage the locking tongue. 
       FIG. 6  is a perspective view of a driving blade, a power spring with a locking tab to engage locking tongue of the lock assembly, and a handle rod for pressing down the power spring. 
       FIG. 7  is a side elevational view of the stapler, shown in a partial sectional view, with the staple retaining panel at an open position. 
       FIG. 8  is a bottom plan view of the stapler with the staple retaining panel snaps to the sidewall of the staple guiding track. 
       FIG. 9  is a section view of the staple feeding track with a coil spring biased pusher inside. 
       FIG. 10  is a section view of the retaining panel snaps to the sidewall of the staple feeding track. 
       FIG. 11  is a side plan view of a handle of the staple retaining panel accommodated in a notch on the sidewall of the staple feeding track. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In the following description, numerous details such as specific materials and configurations are set forth in order to provide a more complete understanding of the present invention. However, it is understood by those skilled in the art that the present invention can be practiced without those specific details. In other instances, well-know elements are not described explicitly so as not obscure the present invention. 
     FIG. 1  shows a housing body  10  with one half removed to expose the internal essential components of the present invention. 
   A driving blade  50  is contained and slidable within a vertical channel  58 . In order to be locked at the top position, the driving blade  50  has a projective member  52  on the top as shown in  FIG. 3A . The projective member  52  forms preferably a right angle to the vertical portion of the driving blade  50 , but can be of any angle approximately from 45 degree to 135 degree as long as the driving blade  50  can engage and disengage a lock assembly. 
   Refer to  FIG. 4A  and  FIG. 4B , the lock assembly includes a spring biased, slidable lock shaft  40 , with a locking tongue  46  in the front. The slidable lock shaft  40  is contained in a substantially horizontal channel  14  formed on the side walls of the housing body  10 . Springs  44  mounted against a stopper  13  of the housing body  10 , bias the lock shaft  40  forward, so that the locking tongue  46  stays beneath the project member  52  of the driving blade, and stops the driving blade  50  from being forced down by a power spring  30 . 
   In another embodiment, there is an opening  57  near the top of driving blade as shown in  FIG. 3B , so that locking tongue  46  can be inserted into the opening  57  for locking the driving blade  50 . 
   The vertical portion of the driving blade  50  is a thin sheet metal form that is substantially flat except for small out-of-plane features, which may be incorporated as a design choice. A completely flat portion of the driving blade  50  may also be used. The thickness of the sheet metal used to make the driving blade is less than the thickness of a standard staple. 
   In order to link the driving blade  50  with the power spring  30 , in one embodiment, there is at least one opening on the flat portion of the driving blade  50  as shown in  FIG. 3A  and  FIG. 3B , so that a front end of the power spring  30  can be inserted into the opening. In another embodiment, there is at least one projective column  56  for the power spring  30  to be hinged on as shown in  FIG. 3C . 
   When the locking tongue  46  slides backward, the driving blade  50  is unlocked. In one embodiment, the unlocking of the driving blade  50  is achieved through an opening  42  on the lock shaft  40 . The opening  42  is so placed that a rod  24  of the handle  20  can go through the opening  42 , and when the handle  20  is pressed down, a rearward facing wedge-like surface  26  on the rod  24  comes into contact with the rear edge of the opening  42 , and forces the lock shaft  40  to slide backward, enough to unlock the driving blade  50  when the handle  20  is pressed to a bottom position. In another embodiment, there is a wedge  43  on the lock shaft  40  with a slanted surface on the front side of the wedge  43 , for the lock shaft  40  being pushed backward by an additional unlocking rod  28  on the handle  20  as shown in  FIG. 5A  and  FIG. 5B . In this case, one biasing spring  45  is mounted on the back of the lock shaft  40 . 
   As shown in  FIG. 4B  and  FIG. 5B , the locking tongue  46  has a bottom tapered front end  47 , so that the driving blade  50  can be pushed up by a return spring  32  to its resting position and being locked. 
   The return spring  32  is mounted underneath the power spring  30 , at a location preferably vertically aligned to the rod  24  of the handle  20 . By mounting the return spring  32  vertically aligned to or rearward of the rod  24 , the urge of the return spring  32  does not resist the downward movement of the power spring  30  when the driving blade is unlocked. Yet, by mounting the return spring  32  vertically aligned to the rod  24  requires lesser amount of urging force of the return spring to return the power spring to its locked position than by mounting the return spring  32  rearward of the rod  24  does. 
   At the resting position, power spring  30  and driving blade  50  are reset to locked position by the urging of the return spring  32 . During stapling operation, the middle section of the power spring  30  is bent by the handle  20  through the rod  24 . With the front end of the power spring  30  being locked by the locking tongue  46 , and a rear end of the power spring  30  being supported by a groove  15  of housing body  10 , the power spring  30  provides a downward bias upon driving blade  50 . When the driving blade  50  is unlocked, the biased power spring  30  will urge the driving blade  50  to move downward, and expels a staple in the front of a staple feeding track  16 . The downward motion by power spring  30  is limited by housing body  10 , so that driving blade  50  does not extrude from the bottom of housing body  10 . 
   The movement of the rear end of the power spring  30  is confined on three sides, bottom, top and rear (the side way movements are contained by the walls of the housing body  10 ), by the groove  15 , which is a part of the housing body  10 . When the middle section of the power spring  30  is pressed down, the front end of the power spring  30  tends to slide backward, but since the power spring  30  is stopped in the rear end by the groove  15 , the power spring  30  can not slide out of driving blade openings  55 . Upward limitation of the rear end of the power spring  30  by the groove  15  ensures the return spring  32  pushes up only the front end of the power spring  30 . 
   The handle  20  is pivotally attached to the rear end of the housing body  10 . A column extension  22  from the rear end of handle  20  inserts into a circular slot formed by walls of housing body  10 , serving as a pivot for handle  20 . Top panel  12  of the housing body  10  limits the travel of handle  20 . It is obvious, that the handle  20  can also be hinged in the front end of the housing body  10 , elongated and extends toward the rear of the housing body. Then the stapler becomes rear operated. 
   The feeding track  16  is formed at the bottom of the housing body  10  as shown in  FIG. 7 . There are guiding slots  18  on both internal sidewalls of the feeding track  16 . A slidable pusher  70  has tabs  72  on both sides, the tabs  72  fit in the guiding slot  18  to retain the pusher  70  inside the feeding track  16  as shown in  FIG. 9 . 
   A retaining panel  60  snaps to the bottom of the feeding track  16  to keep staples inside feeding track  16  during normal operation as shown in  FIG. 8 . At closing position, there is a gap between a front edge of the retaining panel  60  and a front internal wall of the feeding track  16 , the gap forms a staple exit slot to allow expelled staple exit.  FIG. 10  shows that the side wall of the feeding track  16  has a protrusive profile  17  near the bottom.  FIG. 10  also shows the way how the retaining panel  60  snaps to the sidewall of the feeding track. A rear pin  62  formed on the retaining panel  60  is hinged on the rear end of the sidewalls of the feeding track  16  and serves as a hinge for the retaining panel  60 . Handles  64  on both sides of the retaining panel  60  fit into notches  19  formed at the bottom of the sidewalls of the feeding track  16 , to serve both as holding places to pull open the retaining panel  60 , and to stop the retaining panel  60  from being pushed further into the feeding track  16 . The handles  64  optionally snap to the notches  19 . 
   The retaining panel  60  is preferably a thin sheet metal or plastic form, but can also be constructed out of metal wire, as the surface needed to retain staple magazine is only at the two elongated sides of feeding track  16 . 
   A coil spring  65  biases the pusher  70  to push staple(s) forward to the front of the feeding track  16 . When the retaining panel  60  being opened, the coil spring  65  drags the pusher  70  to the rear of the feeding track  16  as shown in  FIG. 7 , exposing the chamber of the feeding track  16  for placing staple magazine.