Abstract:
A desktop stapler having a feature for alignment of the anvil with the striker is disclosed. In one embodiment, a stapler body containing a striker is pivotably attached to a base. The pivoting rotation of the body causes a front-to-back motion of the striker over an anvil. A rib disposed at the back end of the body selectively pulls the back end of a linkage to the anvil backward as the body pivots downward to the stapling position. The anvil thus translates in relation to the body to maintain a close alignment of the striker over the anvil. The base assembly may include a cover plate slidable upon a base, wherein the cover plate includes the anvil. Another embodiment uses a tab that urges a staple track to be forcibly pulled open as the body is rotated away from the base.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to desktop staplers. More precisely, the present invention relates to structures for positioning of a stapler anvil and opening a loading track.  
       BACKGROUND OF THE INVENTION  
       [0002]     A desktop stapler normally includes a lower base portion and a main body pivotally attached to the base. The body pivots toward the base in normal use as the stapler handle is pressed to eject a staple from the staple track. A striker urges a staple out of a staple exit location toward an anvil, where the anvil is immediately under a stack of papers to be fastened together. The anvil bends the legs of the staple so that the legs clinch behind the papers. It is important that the striker remain aligned with the anvil, being neither too much in front nor too rearward of the anvil. Misalignment of the striker and anvil prevents the staple from forming correctly behind the papers since the legs bend forward or rearward where it is desired only that the legs be bent toward each other.  
         [0003]     Such a defective curl or formation of the staple behind the stack of stapled papers renders the staple unsuitable for its intended purpose of fastening the papers together. The user must then somehow unfasten the defective staple and re-staple the stack. Uncurling, detaching or withdrawing the defective staple from the stack is time consuming and an irritation, often requiring use of a staple puller, a bladed tool to slide underneath the staple to pry it loose, or finger pinching manipulation. It is at the very least a nuisance to fix a defective staple and is undoubtedly a waste of productive time.  
         [0004]     Typically the stapler body is pivoted from a position above the base. As the body arcs downward about the pivot into position just above the anvil to eject a staple, the staple exit location underneath the striker translates rearward in relation to the anvil.  
         [0005]     In particular, in a conventional stapler, the translating motion of the striker is rearward as the body moves toward the base since the pivot point is above the level of the base. An analogy is to look at the hands of a clock. If the minute hand is at the 3 o&#39;clock position, the pivot point and the pointer of the hand are horizontally at the same level, but once the hand is pointed toward the 2 or 4 o&#39;clock positions, the horizontal distance of the pointer of the minute hand to the pivot point has shortened as compared to the 3 o&#39;clock position. Through basic trigonometry, if the distance from the pivot point to the striker is radius R, and the angle between the horizontal position of the body and the downward stapling position of the body is θ, then the horizontal distance x that the striker translates toward the pivot point is x=R−(R)(cos θ). On the other hand, if a stapler were designed with the pivot position at or below the level of the base, then the striker translates forward as the body moves toward the base.  
         [0006]     Another alignment consideration is the vertical distance between the striker and the anvil at the beginning of the arcuate movement of the body. If the stapler is of small capacity, such as for stapling less than 20 pages, the amount of striker rearward translation is not significant if the pivot location is not too far above the base. However, in the case of a larger capacity stapler, such as 60 pages, the highest and lowest stapling positions of the body in relation to the anvil are quite different. If the position of the pivot is relatively high above the base, the rearward translation component of the arcing motion is further increased. Consequently, it is desirable to have a mechanism in a stapler that can closely maintain the striker to anvil alignment in spite of the front to rear translating motion and regardless of the paper capacity.  
       SUMMARY OF THE INVENTION  
       [0007]     In one preferred embodiment of the present invention, a stapler base and body are pivotably attached to each other. Optionally, the base and body are slidably attached to each other. When the body pivots in an arcing motion over the base, the lower part of the body translates rearward over the base as part of the arcing motion. The sliding motion between the body and base, however, compensates for this rearward translation element of the arc.  
         [0008]     According to one embodiment of the invention, the base includes a base assembly with two elements movable with respect to each other, a base structure, and a cover plate. The body is pivotably attached to the base assembly, while the cover plate may slide along the base structure. A resilient member biases the cover plate toward a normal position on the base assembly. When a pressing-surface of the body engages the cover plate, the cover plate moves rearward upon the base. This engagement occurs at a predetermined position of the body over the base.  
         [0009]     Alternatively, the body may be pivotable and slidable in relation to the base, and in this embodiment the base and body may be a single hinged structure.  
         [0010]     A further embodiment of the present invention includes a tab extending down from a staple track. As the body is opened away from the base, this tab is forced to move rearward so that the track is assured to be in an unlatched position before the stapler is fully opened. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a side elevational view of a stapler that includes elements of the present invention.  
         [0012]      FIG. 2  is a partial cross-sectional view of the stapler of  FIG. 1 , showing components of a spring-actuated stapler.  
         [0013]      FIG. 3  is a magnified, cross-ectional view of elements of the present invention at a rear of the stapler encircled and labeled  3  in  FIG. 2 .  
         [0014]      FIG. 4  is a side elevational view of a stapler track.  
         [0015]      FIG. 5  is an upper side elevational view of a cover plate for a base.  
         [0016]      FIG. 6  is a side elevational view, partly in cross-section, of the stapler of  FIG. 2  with the body pivoted partially toward the base.  
         [0017]      FIG. 6A  is a magnified, cross-sectional view of a rear portion of the stapler with a pressing-surface of the body contacting the cover plate, encircled and labeled as  6 A in  FIG. 6 .  
         [0018]      FIG. 7  is a side elevational view, partly in cross-section, of the stapler of  FIG. 6 , with the body pivoted downward to its limit against the anvil.  
         [0019]      FIG. 7A  is a magnified, cross-sectional view of an encircled area in  FIG. 7 , with the pressing-surface urging the cover plate rearward.  
         [0020]      FIG. 8  is a side elevational view of a stapler, with cut-away sections, with the body pivoted partly away from the base.  
         [0021]      FIG. 9  is the stapler of  FIG. 8  depicted in a side elevational view and showing the body pivoted slightly farther from the base. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]     In the exemplary embodiment of the present invention described below, a spring actuated stapler is shown. In such a spring-actuated stapler, the striker is energized and actuated by the potential energy stored in a spring, rather than from inertia generated by a user pushing down on the actuation handle in a conventional stapler. In one version of a spring-actuated desktop stapler, pressing down on the actuation handle lifts the striker upward against the bias of a power spring. When the striker is lifted past a certain point, it is released from the handle and the power spring accelerates the striker downward into a staple which upon impact is ejected from the stapler.  
         [0023]     In another version of a spring-actuated stapler, the striker has a rest position above the staple track rather than in front of the staple track. Pressing the actuation handle energizes a spring that is linked to the striker. The striker is released at a predetermined position of the handle and the striker moves down to eject a staple. In the reset action, the assembly of the handle, striker, and spring all move upward together to the rest position. Although the following exemplary embodiments of the present invention are described in connection with a spring-actuated stapler, it is contemplated that the present invention can also be applied to a conventional stapler.  
         [0024]     In  FIG. 1 , a stapler includes pivot  90  attached to sidewalls  23  of base  20 . Body  10  pivots in relation to base  20  about pivot  90 . Pivot  90  is spaced above cover plate  100 ,  FIG. 5 , by the “Pivot/Anvil Distance” where cover plate  100  includes anvil  102 ,  FIG. 2  formed into cover plate  100 . It may be desired to locate this tall position for pivot  90  so that body  10  can be fully opened when it is pivoted by a half rotation to extend rearward from base  20  (not shown) with track pull  130  well exposed for access. In this configuration, track  70  can be slid out from its position within body  10  by pulling on track pull  130 . Track  70  would slide to the left in  FIG. 2  if body  10  were fully opened as described.  FIG. 9  shows an intermediate position of this rearward rotation.  
         [0025]     Still in  FIG. 2 , if pivot  90  were located below the horizontal level of the cover plate  100 , then the respective directions of movements between body  10  and base  20  would be reversed.  
         [0026]     The front bottom area of body  10  includes a lower end of striker  80 . Striker  80  is preferably made from a metal and freely travels linearly along tracks or grooves inside body  10 . In the “uppermost body position,” shown in  FIGS. 1 and 2 , body  10  is at rest above base  20  providing more space than required for a maximum number of paper sheets. The extra space eases the insertion of papers upon anvil  102 , underneath striker  80 .  
         [0027]     In  FIG. 2 , the basic components of one type of a spring-actuated stapler are shown. Body  10  contains lever  40 , which pivots at an intermediate position thereof about post  44  and is biased by reset and/or power springs  95 ,  98 . Wheel  42  or bearing surface rolls or slides upon ramp  33  within handle  30  as the handle is pressed downward by a user. A front end of lever  40  releasably engages or latches a slot opening in striker  80 . With the front end of lever  40  initially linked to striker  80 , the user pressing handle  30  downward rotates lever  40  about pivot  44  against the reset spring bias, which rotation lifts striker  80  upward against the power spring bias. Once reaching a predetermined rotational position with lever  40 , striker  80  is suddenly de-linked from lever  40 . With the opposing force supplied by lever  40  suddenly removed, power spring  98  accelerates striker  80  downward in a driving stroke. Near the bottom of the driving stroke, striker  80  impacts and ejects a staple from front end  71  of track  70  containing a bundle of staples.  
         [0028]     With the staple ejected, the user removes pressure on the handle  30 . Reset spring  95 , which engages a rear distal end of lever  40 , biases handle  30  upward to return it to the start position. The front end of lever  40  travels downward and again latches against the slot opening in striker  80 . The stapler is now ready to fire the next staple.  
         [0029]     Body  10  moves downward from its uppermost position as handle  30  is pressed, pivoting about pivot  90 . Track pull  130  is fitted to the rear end of track  70  to releasably hold track  70  within body  10 . Base  20  is part of a base assembly including cover plate  100 . Cover plate  100  is held down in base  20  optionally at the front thereof by tab  104 . Base spring  24  engages edge  106  of the cover plate, urging the cover plate forward against a stop such as at tab  104 .  
         [0030]     Cover plate spring  115 , as best seen in  FIG. 5 , holds body  10  in the raised position. Pressing-surface  13 ,  FIG. 3 , is preferably an element of body  10  and is spaced from rib  112  of cover plate  100  in its normal, uppermost, position shown in  FIGS. 1 and 2 . Therefore, pressing-surface  13  is de-linked from cover plate  100  and anvil  102  in the uppermost body position, and striker  80  is not precisely aligned vertically with anvil  102 . Optionally, pressing surface  13  may engage rib  112  for all normal positions of body  10 . However, cover plate  100  will then slide a greater distance upon base  20  than is required for actual stapling positions of body  10 . This would require, for example, that base spring  24  flex more than necessary. Track  70  includes force-open tab  72  discussed below.  
         [0031]     More precisely depicted in  FIGS. 6 and 6 A, body  10  is pivoted to a “high body position” toward base  20 . The high body position is below the uppermost body position depicted in  FIGS. 1 and 2 . The vertical space between striker  80  and anvil  102  is about equal to a thickness of the maximum rated stack of papers intended for the stapler. For example, the stapler shown in the drawing figures may have a 60 page capacity, then the space above anvil  102  would fit about 60 pages. The space above the anvil is preferably about 0.5-0.8 inch in the uppermost body position, and about 0.1-0.4 inch in the high body position. Of course, for industrial or heavy duty commercial applications, the space above the anvil may be greatly enlarged to accommodate larger stacks of papers that may be made from thicker material.  
         [0032]     In the high body position of  FIGS. 6 and 6 A, pressing-surface  13  just contacts rib  112 , but cover plate  100  has not yet moved rearward. Nevertheless, pressing-surface  13  and anvil  102  are now linked via cover plate  100 . The position of cover plate  100  is referenced at front reference number  100 A and rear reference number  100 B in  FIGS. 6 and 6 A, respectively.  
         [0033]     In  FIG. 7 , body  10  is pivoted downward to its limit at a “lowest body position” wherein striker  80  is in contact with cover plate  100  and/or anvil  102 . This is, for example, approximately the position that corresponds to stapling the minimum of two sheets of paper. A larger stack of paper would cause the lowest position to be increased accordingly. At reference numbers  100 A and  100 B, it can be seen that cover plate  100  has moved rearward from that shown in  FIG. 6 . The gap at  100 A in front of tab  104  has increased while rib  112  has moved to rearward in  FIG. 7A . The different cover plate positions, due to its horizontal translation, are thus apparent in comparing  FIGS. 6 and 7 . To enable this fore-aft translation of cover plate  100  relative to base  20 , the lengthwise dimension of the opening receiving cover plate  100  therein is slightly greater than the length of cover plate  100 . Alternatively, the opening can be omitted so that the cover plate is slidably attached to a top surface of the cover plate and.  
         [0034]     One purpose of this fore-aft translation of cover plate  100  is to maintain the alignment of anvil  102  underneath striker  80  which when contained inside body  10  travels in an arc around pivot  90 . In  FIG. 2 , striker  80  is aligned vertically in front of anvil  102 . That is not important at this moment, however, since the stapling operation does not occur in this highest body position. Indeed, the highest body position advantageously serves to facilitate inserting a stack of papers to be stapled.  
         [0035]     In  FIG. 6  the stapler body is in the highest position in which stapling actually will occur, using the largest expected stack of papers. At this position, striker  80  is precisely or much more precisely than in conventional staplers, aligned over anvil  102 , i.e., in the fore/aft direction. As body  10  pivots farther toward base  20 , the bottom of striker  80  moves rearward along base  20 . This is a result of the high position of pivot  90  and the arcing motion that results therefrom. Beginning at the downward progressing position shown in  FIG. 6 , pressing-surface  13  makes contact with rib  112  of cover plate  100  and begins to urge cover plate  100  with anvil  102  rearward.  
         [0036]     Pressing-surface  13  is near the same vertical position as the bottom of striker  80  and anvil  102 . Therefore, rib  112  preferably moves rearward the same distance as the bottom of striker  80 . As seen in  FIG. 7 , the bottom of striker  80  remains fairly precisely aligned with anvil  102 .  
         [0037]     As seen in  FIGS. 3 and 5 , pressing-surface  13  preferably has a blade shape and extends downward and rearward from body  10 , while rib  112  bends upward from cover plate  100  in the manner of a slight hook. The leading edge of the blade shape of pressing-surface  13  slidably engages the hooked surface of rib  112  as seen in  FIG. 6A .  
         [0038]     Other means of selectively linking the movement of the body containing the striker to actuate fore/aft translation of the anvil located in the base are contemplated. For example, the pressing-surface can be one or more bumps, claws, half-crescents, raised contours, or the like that grasp, engage, or otherwise latch onto the rib, slot, groove, stop, bump, ramp, or like structure to cause the rearward translation of anvil  102  via cover plate  100  as body  10  moves toward base  20 . The locations of the pressing-surface and the rib can be situated anywhere near the back end of the stapler insofar as the rotational movement of body  10  relative to pivot  90  can be efficiently transferred to the translational movement of the anvil through the cover plate or other linkage.  
         [0039]     Optional base spring  24  presses edge  106  of cover plate  100  to bias the plate forward. In  FIG. 7  it is seen that base spring  24  is deflected rearward from its position of  FIG. 6  since cover plate  100  has been moved rearward. Cover plate spring  115  biases body  10  upward. Therefore, as a user releases the stapler, body  10  moves upward and base spring  24  returns to its normal shape of  FIG. 6  and translates the cover plate  100  forward. Cover plate  100  then returns to its rest position shown in  FIG. 2, 3 , or  6 . In the illustrated embodiment, base spring  24  is a cantilevered element of molded base  20 . Other types of base springs may be used and their location can be changed to suit design needs.  
         [0040]     According to an alternative embodiment (not shown), the base assembly includes a slidable anvil linked to the pressing-surface by a bar or other structure that engages the anvil and pressing-surface. For example, the anvil can be formed into a small plate slidably disposed in an opening near the front end of the base. A flat bar or small wire extending along the major length of the base curls or bends upward at the back end to link with the pressing-surface. The flat bar, wire, or the like then serves as the linkage to translate the small plate containing the anvil rearward, and the need for a cover plate has been eliminated.  
         [0041]     In one alternative embodiment, the base of the stapler is a single element without a slidable cover plate or anvil. However, alignment according to the present invention may still be accomplished. Specifically, shown in  FIG. 2 , pin  92  extends laterally from body  10  would engage optional elongated slot  94  in either of sidewalls  23  so that body  10  is capable of translating along front and rear pivot positions at the dimensional extremes of elongated slot  94 .  
         [0042]     Then pressing-surface  13  pivots upon what is now an immovable or immobile rib  112 , or an equivalent structure, while body  10  translates slightly forward between the respective pivot positions of elongated slot  94  in relation to sidewalls  23 . The bottom of striker  80  arcs nearly vertically at anvil  102  since the pivot point at immobile rib  112  is near the same vertical position as anvil  102 . In this alternative embodiment, body  10  is in a rear position at pivot  90  with respect to sidewalls  23  in the uppermost and high positions of FIGS.  1  to  6 . In the lowest position of  FIG. 7 , body  10  is translated slightly forward at pivot  90  with respect to sidewalls  23 . Accordingly, with either a movable cover plate embodiment or a fixed cover plate embodiment, the striker and anvil remain aligned for the various quantities of papers to be stapled.  
         [0043]     In  FIGS. 8 and 9 , a structure is shown that forces track  70  to open slightly as body  10  is pivoted upward from base  20 . If a staple becomes jammed at front end  71  of track  70 , striker  80  may stay in the raised position and power spring  98  stays energized. If a user fully opens the stapler so that the bottom of body  10  faces upward, the striker may suddenly release if the user forcefully pulls the track open by tugging on track pull  130 . It is desirable to pull the track open slightly before the stapler is fully opened.  
         [0044]     In  FIG. 8 , body  10  is pivoted to a first open position away from base  20 . Track tab  72  extends downward toward cover plate  100 , also seen in  FIG. 4 , and contacts spring tab  110 . Spring tab  110  is an element of base  20  or the base assembly including cover plate  100  and base  20 . In  FIG. 9 , body  10  is pivoted to a second open position farther from base  20 . As body  10  is raised to the second open position of  FIG. 9 , the contact between track tab  72  and spring tab  110  continues. It is seen that this is a sliding contact wherein track tab  72  has moved upward along spring tab  110  as body  10  rises between the position of  FIGS. 8 and 9 . At the same time, track tab  72  is biased forward as body  10  arcs about pivot  90 . However, track tab  72  cannot move forward since spring tab  110  is not substantially movable. Thus, track tab  72  and track  70  are forced to slide rearward, to the right in  FIGS. 8 and 9 , in relation to body  10  after track pull  130  has been unlatched from body  10  through a further mechanism (not shown).  
         [0045]     In  FIG. 8 , track front end  71  is immediately adjacent to striker  80  in a track operating position. Spring tab  110  and track tab  72  have just made contact in this track operating position. In  FIG. 9 , track front end  71  is spaced to the rear of striker  80  in a rearward unlatched track position as the spring tab and track tab continue to engage. Upon further rotation of body  10  upward (not shown) past the second body open position, track tab  72  rises upward out of engagement with spring tab  110  so track  70  is not forced to slide farther rearward through this mechanism.  
         [0046]     In the preferred embodiment, body  10  is formed from a polymer shell as is base  20 . Since the preferred embodiment stapler operates under spring power rather than by inertial impact applied in conventional, direct handle-to-striker staplers, these components do not require the strength of metal and can be made from lightweight polymers. Material costs based on polymers as opposed to metals are reduced. Use of polymers reduces weight, bulk, and eliminates possibility of rusting.  
         [0047]     Accordingly, the polymer shell of base  20  may be made from glass filled polypropylene, polycarbonate, or the like. The polymer shell may optionally be formed in halves and made from high strength, low friction nylon. Of course, other materials may be used such as die cast metal. Die cast metal may be desirable if higher weight is needed. Anvil  102  is preferably formed into cover plate  100 . Cover plate  50  may be made from steel, plastic, or other non-ferrous material.  
         [0048]     From the foregoing detailed description, it should be evident that there are a number of changes, adaptations and modifications of the present invention that come within the province of those skilled in the art. However, it is intended that all such variations not departing from the spirit of the invention be considered as within the scope thereof except as limited solely by the following claims.