Patent Publication Number: US-7909218-B2

Title: Safety apparatus for spring powered staplers

Description:
BACKGROUND 
     The present invention relates generally to staplers, and more specifically, to safety apparatus for spring-powered staplers. 
     A key for a staple to have good penetration is its entry speed. A spring powered stapler uses a spring to store energy. Upon a release of the stored spring energy, a staple can be driven out at a great speed. However, a fast exit staple may shoot like a bullet which poses a safety concern for the spring powered stapler. As such, what is needed is a safety apparatus for the spring powered stapler. 
     SUMMARY 
     In view of the foregoing, the present invention provides a safety apparatus for a stapler having a power spring for storing energy as well as urging a driving blade to expel a staple upon releasing the stored energy, the safety apparatus comprising a lock plate having a top section holding up the power spring for storing energy when the top section of the lock plate being in a first position, and releasing the power spring when the top section of the lock plate being moved substantially horizontally to a second position, a first spring for urging the top section of the lock plate to the first position, a safety pin substantially vertically movable between a third and fourth position, the safety pin being in the third position when the stapler is not pressed against an object for being stapled, and the safety pin being in the fourth position when the stapler is pressed against an object for being stapled, and a second spring for urging the safety pin to the fourth position, wherein when in the third position, the safety pin stops the lock plate from being moved to the second position, and when in the fourth position, the safety pin makes room for the lock plate to be moved to the second position. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings accompanying and forming part of this specification are included to depict certain aspects of the invention. A clearer conception of the invention, and of the components and operation of systems provided with the invention, will become more readily apparent by referring to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings, wherein like reference numbers (if they occur in more than one view) designate the same elements. The invention may be better understood by reference to one or more of these drawings in combination with the description presented herein. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale. 
         FIG. 1  is a side partial sectional view of a spring powered stapler with a safety apparatus in a resting position according to one embodiment of the present invention. 
         FIG. 2A  is a side partial sectional view of the spring powered stapler of  FIG. 1  just prior to ejecting a staple. 
         FIG. 2B  is a side partial sectional view of the spring powered stapler of  FIG. 1  which is prevented from ejecting a staple when a safety pin is not pushed in. 
         FIG. 3  is a perspective view of key elements of the safety apparatus for the spring powered stapler of  FIG. 1 . 
         FIG. 4  is a perspective view of key elements of an alternative safety apparatus for the spring powered stapler of  FIG. 1 . 
     
    
    
     DESCRIPTION 
     The present invention provides a safety apparatus to a spring powered stapler. The safety apparatus is to ensure when the spring powered stapler is not firmly pressed against an object, attempts to operate the spring powered stapler will not result in any expulsion of staples. 
       FIG. 1  is a side partial sectional view of a spring powered stapler having a safety apparatus in a resting position according to one embodiment of the present invention. The spring powered stapler comprises a housing body  10 , a handle  20 , a power spring  50 , a return spring  55 , a driving blade  60 , and a release assembly including a release plate  70 , a safety pin  80  and a release block  90 . There is a first push-down rod  22  affixed on the handle  20  for urging the middle section of the power spring  50  to bend downward for storing spring energy when the handle  20  is pressed down. There is also a second push-down rod  24  affixed on the handle  20  closer to the front of the handle  20  for forcing the release block  90  to move downward when the handle  20  is pressed down. A front section of the power spring  50  engages the driving blade  60  through an opening  62  thereon. A rear end of the power spring  50  is confined by the housing body  10  and cannot move either vertically or backwardly. The lock plate  70  has at least one locking hole  72  and a safety-pin hole  75 . The lock plate  70  is stopped by a fixture on the housing body  10  (not shown) from swing further downward, so that the power spring can be held up. When a front end of the power spring  50  is inserted in the locking hole  72 , the power spring is locked thereby in a high position. The lock plate  70  is pushed frontward by a wedge-like surface  92  of the release block  90  when the release block  90  is pressed down by the handle  20 . When the lock plate  70  is pushed frontward enough, the locking hole  72  thereon will disengage with the power spring  50 . Then the power spring  50  will force the driving blade  60  to move downward to expel a staple (not shown) out of the staple feeding track. 
     Referring again to  FIG. 1 , a bottom end of the lock plate  70  is confined by a groove  78  which is affixed on the housing body  10 . A top end of the lock plate  70  is pushed backward by a lock-plate push spring  77 . When the top end of the lock plate  70  is pushed to a backward position, the front end of the power spring  50  is inserted into the locking hole  72  of the lock plate, so that the lock plate  70  prevents the power spring from releasing energy. The wedge-like surface  92  on the release block  90  pushes the top end of the lock plate  70  frontward to release the power spring  50 , when the handle  20  is pressed low enough. When the handle  20  is released, a push-up spring  95  will push up the release block  90 , so that the lock-plate push spring  77  can push the top end of the lock plate  70  backward to lock the power spring  50 . The lock plate  70  is resting at an angle toward the rear end of the housing body  10 , so that the lock plate  70  will not interfere with the power spring  50  when it is released and slams down. When the handle  20  is released, the return spring  55  pushes up the power spring  50 , overcoming the urge of the lock-plate push spring  77 , to the resting position as shown in  FIG. 1 . 
     Referring again to  FIG. 1 , a staple feeding track is formed at the bottom of the housing body  10 , which comprises a staple retention panel  40 , a sliding block  45  pulled forward by a drag spring  42  for pushing a staple magazine toward the front end of the staple feeding track. The sliding block  45  is confined by a pair of horizontal slots  47  formed on each internal side walls of the feeding track. In the resting position, the spring powered stapler sits on a base plate  30 . A base spring  32  urges the base plate  30  away from the housing body  10 , so that a stack of paper or other objects can be inserted under the housing body to be stapled. 
       FIG. 2A  is a side partial sectional view of the spring powered stapler of  FIG. 1  just prior to ejecting a staple. A stack of paper  102  is place underneath the housing body  10  and pushes the safety pin  80  to an upper position where a safety-pin protruding member  85  is inserted into the safety-pin hole  75  on the lock plate  70 . Therefore, the lock plate  70  can move freely frontward to allow the power spring  50  to be released. 
       FIG. 2B  is a side partial sectional view of the spring powered stapler of  FIG. 1  which is prevented from ejecting a staple when a safety pin  80  is not pushed in. In this case, there isn&#39;t any object underneath the housing body  10  to push in the safety pin  80 . If the power spring  50  is allowed to release and expel a staple, the staple may be shot out at a very fast speed and cause safety concerns. The present invention employs the safety pin  80  to prevent this from happening. When there is no object placed beneath a bottom tip  82  of the safety pin  80 , a safety spring  87  urges the safety pin  80  to a lower position where the safety-pin protruding member  85  is misaligned with the safety-pin hole  75  on the lock plate. Instead of inserted into the safety-pin hole  75 , the safety-pin protruding member  85  comes into contact with the wall of the lock plate  70  which is made of a rigid material, such as steel. The safety pin  80  is limited by a channel (not shown) formed as part of the housing body  10  to slide only vertically. As a result, in this case, the lock plate  70  cannot be pushed frontward to release the power spring  50 . 
       FIG. 3  is a perspective view of key elements of the safety apparatus for the spring powered stapler of  FIG. 1 . The key elements are the safety pin  80  and the lock plate  70 . The safety spring  87  urges the safety pin to the lower position. The safety-pin hole  75  has a right dimension to accommodate the safety-pin protruding member  85 . There are two locking holes  72  for engaging the power spring  50 . The locking holes  72  and the safety-pin hole  75  are not vertically aligned, so that the front end of the power spring  50  will not insert in the safety-pin hole  75  when the power spring  50  is release and slide downward. Both the lock plate  70  and the safety pin  80  are made of rigid materials, such as steel. 
       FIG. 4  is a perspective view of key elements of an alternative safety apparatus for the spring powered stapler of  FIG. 1 . The alternative safety apparatus comprises a lock plate  71  and a safety pin  81 . The lock plate  71  is identical to the lock plate  70  of  FIG. 3  except a protruding member  76  on the lock plate  71  takes the place of the safety-pin hole  75  on the lock plate  70  of  FIG. 1 . Correspondingly, instead of having a protruding member  85  on the safety pin  80  of  FIG. 3 , the safety pin  81  has a concave member  86  thereon. When the safety pin  81  is in a lower position, the concave member  86  is not aligned with the protruding member  76  on the lock plate  71 , and the shaft of the safety pin  81  comes into contact with the protruding member  76  on the lock plate  71 , and prevent the same from moving frontward to release the power spring  50 . When the safety pin  81  is in an upper position, the concave member  86  becomes aligned with the protruding member  76  on the lock plate  71 , and allows the lock plate  71  to move frontward to release the power spring  50 . 
     The above illustrations provide many different embodiments or embodiments for implementing different features of the invention. Specific embodiments of components and processes are described to help clarify the invention. These are, of course, merely embodiments and are not intended to limit the invention from that described in the claims. 
     Although the invention is illustrated and described herein as embodied in one or more specific examples, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention, as set forth in the following claims.