Patent Publication Number: US-7584878-B2

Title: Paper tool drive linkage

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 60/715,254 filed on Sep. 8, 2005, the entire content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a paper tool. More particularly, the invention relates to a paper punch, stapler, or paper trimmer having an improved linkage to provide a mechanical advantage to the paper tool. 
     BACKGROUND OF THE INVENTION 
     Paper tools, including paper punches, staplers, and paper trimmers, are configured such that force input by a user results in an operation on paper or other substrates. For example, in a typical paper punch, the user actuates a handle, which causes a punch pin to move downwardly to punch a hole in a stack of sheets inserted into the punch. Punches that employ a linkage to actuate the punch typically include links generally aligned above a vertically oriented punch mechanism. The linkage increases the mechanical advantage within the punch such that less force input is required from the user to perform the punching operations. Staplers are also known that include linkages for increasing the mechanical advantage of the stapler during stapling operations. Paper trimmers can also be configured to contain similar linkages for increasing mechanical advantage. 
     Four-bar linkages are known in the construction of paper punches and staplers. One example of such a four-bar linkage in a paper punch is shown in U.S. Pat. No. 6,688,199 and prior-art  FIG. 1 .  FIG. 1  illustrates a paper punch  100  generally including a base  110 , punch pins  112  (only one shown), and a linkage for actuating the punch pins  112 . The linkage is configured as a four-bar linkage including a drive member  114 , a first end cap  118 , and a handle member  122 . The drive member  114  is pivotably coupled to the base  110  at pivot  120 , and the handle member  122  is pivotably coupled to the drive member  114  at pivot  126 . The handle member  122  is also pivotably coupled to a second end cap (not shown—positioned at one end of the punch  100 ) at pivot  134 , while the second end cap is pivotably coupled to the base  110  at pivot  138 . 
       FIG. 1  also schematically illustrates the “links” representative of the base  110 , drive member  114 , handle member  122 , and the second end cap in a four-bar linkage. The base  110  is schematically illustrated by link  142 , which is representative of the “ground,” which is stationary in a four-bar linkage. The second end cap is schematically illustrated by link  146 , which is representative of the “crank” in a four-bar linkage. The drive member  114  is schematically illustrated by link  150 , which is representative of the “rocker” or “output link,” which provides the output force or motion to the pivot pins  112 . The handle member  122  is schematically illustrated by link  154 , which is representative of the “coupler” or “coupler link,” which connects the link  146  (the “crank”) and the link  150  (the “rocker”) in the four-bar linkage. 
     Such a four-bar linkage, when utilized in a paper punch, includes three movable links (i.e., the links  146 ,  150 ,  154 ) and a sliding point of contact, whether rotationally sliding or through an elongated cam slot. In the paper punch  100  illustrated in  FIG. 1 , a push bar in the form of a cylindrical rod  158  is received in respective grooves  162  in the drive members  114 . During actuation of the punch pins  112 , sliding contact occurs between the rod  158  coupled with the drive members  114  and the punch pins  112  to transfer the pivoting motion of the drive members  114  to linear motion of the punch pins  112 . 
     In typical manually-operated staplers, the upper cover often directly applies a force to the staple driver to drive a staple into a stack of sheets or other materials. Other staplers, such as the staplers shown in U.S. Pat. Nos. 6,966,479, 6,550,661, 6,776,321, and 6,179,193, have used the leverage provided by two pivots and a sliding contact, rather than a four-bar linkage. Such staplers have only a main body pivot and a cover or handle pivot. The pivot between the magazine and the cover can facilitate opening the stapler for staple loading. Cam slots have been used in staplers, such as the stapler shown in U.S. Pat. No. 6,966,479, but only to provide clearance for opening the upper cover when loading staples into the stapler magazine. Such cam slots have not been used in the mechanism or linkage that transmits power to the staple driver. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a paper tool, such as a paper punch, a stapler, or a paper trimmer, for acting on a workpiece (e.g., a stack of sheets). In one embodiment of the invention, a paper punch includes a linkage that functions in a manner similar to a four-bar linkage to provide mechanical advantage during a punching operation, however, only two movable links are provided. By using the linkage of the present invention, the simulated pivot point of the eliminated third movable link may be placed in positions which give greater mechanical advantage but would be impractical when using a physical link. The elimination of the third movable link allows a less complex device both by reducing the number of components related to the eliminated third movable link, and also by allowing for the simplification of the paper tool as there is no longer a requirement to provide a mounting point and related structure for the eliminated third movable link. 
     The present invention includes a linkage having at least one pivot that provides for both rotational and translational movement between the respective coupled members. In one embodiment, such a pivot is formed by positioning a radial or an arcuate slot at one of the linkage pivots, such as the handle or cover pivots in the illustrated embodiments. The arcuate slot defines a radius, the center of which corresponds with the simulated pivot point of the eliminated third movable link. The handle or cover pivot also includes a pin or a projection received in the arcuate slot. Relative movement between the projection and the arcuate slot defines an arcuate path that simulates the constraining path or movement that would otherwise be provided by the eliminated third movable link. 
     Slots have been previously used in four-bar linkages and in conjunction with linkages having fewer pivot points, but these slots have not been the pivots of the linkages and have created limitations in the mechanical advantage offered. Known slots in a variety of linkages allow a sliding contact at some point within the linkage (not at a linkage pivot), so the application of force may remain at a known point. These linkages allow neither the simplification nor the mechanical advantage available when using a radial or arcuate slot at a linkage pivot and as a substitute for one of the movable links itself. The improvement is enabled by the configuration of the two remaining movable links and other structure so that the strength of the components themselves act in place of the eliminated third movable link. Thus, the linkage of the present invention delivers the full mechanical advantage of a traditional four-bar linkage with fewer physical links and pivots. Though the linkage of the present invention is first described in detail below with respect to use in a punch, it is also described and illustrated for use in a stapler to generate mechanical advantage during stapler operations. Similarly, the linkage of the present invention could be used in a paper trimmer or other paper tools. The movable pivot (i.e., the pivot that provides relative rotation and translation between the coupled members) in the linkage of the present invention could be applied to various pivots or could also be applied to more than one pivot, thereby simulating an additional movable link. This would allow a four-bar linkage to act as a five-bar linkage and so forth, generating additional mechanical advantage without the complexity of additional physical links. 
     The present invention provides, in one aspect, a power transmission linkage for a paper tool. The linkage includes at least three pivots connecting members of the linkage. At least one of the pivots provides both rotational and translational movement between two linkage members connected by the at least one pivot. In one embodiment, the linkage transmits power to an output member, and an engagement between the linkage and the output member occurs at a point distinct from the at least three pivots. 
     The present invention provides, in another aspect, a paper tool. The paper tool includes a power transmission linkage. The linkage includes a base, a drive link, an input member, and at least three pivots connecting members of the linkage. At least one of the pivots provides for both rotational and translational movement between two members connected by the at least one pivot. 
     The present invention provides, in yet another aspect, a paper tool including a base member, a drive link member pivotably coupled to the base member at a first pivot, and an input member pivotably coupled to the drive link member at a second pivot and pivotably coupled to the base member at a third pivot. At least one of the pivots provides for both rotational and translational movement between respective members connected by the at least one pivot. 
     Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a prior art paper punch utilizing a four-bar linkage. 
         FIG. 2  is a perspective view of a paper punch according to one embodiment of the present invention. 
         FIG. 3  is a front view of the punch of  FIG. 2 . 
         FIG. 4  is a side view of the punch of  FIG. 2 . 
         FIG. 5  is a perspective view of the punch of  FIG. 2  with a punch cover removed to reveal the punching units. 
         FIG. 6  is a side view, with normally hidden portions shown for clarity, of the punch of  FIG. 2 , illustrating a handle in an uppermost position and a punch pin in a retracted position. 
         FIG. 7  is an enlarged view of  FIG. 6 . 
         FIG. 8  is a view similar to that of  FIG. 7 , illustrating the handle pivoted downwardly and the punch pin partially extended. 
         FIG. 9  is a view similar to that of  FIG. 8 , illustrating the handle pivoted further downwardly and the punch pin extended further. 
         FIG. 10  is a view similar to that of  FIGS. 7-9 , illustrating the handle in a lowermost position and the punch pin fully extended. 
         FIG. 11  is a schematic view of a linkage for driving a punch pin of the punch of  FIG. 2 . 
         FIG. 12  is a side view, with normally hidden portions shown for clarity, of a stapler according to another embodiment of the present invention, illustrating an stapler cover in an uppermost position and a staple driver in a retracted position. 
         FIG. 13  is a view similar to that of  FIG. 12 , illustrating the stapler cover pivoted downwardly and the staple driver extended. 
         FIG. 14  is a view similar to that of  FIGS. 12 and 13 , illustrating the stapler cover in a lowermost position. 
         FIG. 15  is a schematic view of a linkage for driving the staple driver of the stapler of  FIG. 12 . 
     
    
    
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     DETAILED DESCRIPTION 
     With reference to  FIGS. 2-11 , a punch  10  embodying the present invention is shown. The punch  10  is preferably configured to perform a punching operation on a workpiece, such as displacing, preferably by shearing, a piece of a workpiece with respect to the remainder of the workpiece, punching a hole or stamping a depression or countersink in the workpiece, stamping to form a raised or depressed feature in a workpiece, or embossing the workpiece. Preferred workpieces for use with punches of the present invention include paper, cardboard, plastic, wood, or metal. Typically, the workpieces are in the form of one or more sheets such as a single sheet of paper or a stack of sheets of paper. In a preferred embodiment, the punch  10  is configured to punch at least one hole in a sheet of paper or stack of paper sheets, and can punch two, three, four, or more holes as desired. The punch  10  of the illustrated embodiment is configured to receive the paper within a slot  12  (see  FIG. 4 ) in a substantially vertical configuration, though it is understood that the punch can have other configurations, including configurations permitting generally horizontal insertion of the paper. The punch  10  also includes a paper support surface  13 . 
     As shown in  FIG. 2  and  FIGS. 5-11 , the punch  10  includes one or more punch heads  14  configured to perform the punching operation. The punch heads  14  are protected by a punch cover  16  (see  FIGS. 2 and 3 ). As each punch head  14  is substantially the same, only one punch head  14  will be described. The punch head  14  includes a punch pin  18  movable through a punch pin path, and a punch housing  20  that supports the punch pin  18  and through which the punch pin  18  moves (see  FIGS. 5-11 ). Alternatively, the punch head  14  may include a die blade or plate with one or more punching elements, such as teeth or serrations, to punch the workpiece. The illustrated punch housing  20  includes an integrally formed hinge portion  21  (see  FIG. 11 ). The punch  10  includes a base  22  (see  FIGS. 2-10 ) configured to stably support the punch  10  on a support surface, the base  22  supporting the punch housing  20  thereon. In the illustrated construction, the punch housing  20  is secured to the base  22 . In an alternative construction of the base, the punch housing  20  and/or the hinge portion  21  may be integrally formed with the base  22  as one piece. 
     The punch  10  also includes a handle  26  that is configured to receive force input from a user of the punch  10  and is rotatable with respect to the base  22 . Alternative arrangements, such as a button or the like, may also be employed to impart the actuation motion. A motor, such as an electrical motor, or a solenoid may be also be used to impart the actuation motion. In other words, the linkage of the present invention can be incorporated in manually-operated punches like the punch  10 , or in electrically-operated punches. The base  22  also includes a receiving member  24  (see  FIGS. 2 ,  4 , and  5 ) that is configured to receive the paper chips expelled during punching operations. The receiving member  24  includes a removable cover  25 . 
     With reference to  FIGS. 5-10 , the punch  10  includes a drive linkage  64  that imparts a mechanical advantage in the punch  10  to reduce the amount of force input required from the user to operate the punch  10 . The linkage  64  includes a drive link or a lever  28  associated with each punch head  14  and pivotably coupled to the base  22  at a fixed pivot  30 . In the illustrated construction, the fixed pivot  30  is defined in part by the hinge portion  21  of the punch housing  20 , which, in turn, is secured to the base  22 . As previously stated, the punch housing  20  and/or the hinge portion  21  may be integrally formed with the base  22  as one piece, such that the pivot  30  may be located directly on the base  22 . 
     The lever  28  includes an upper collar  38  that is rotationally coupled to a shaft  42  that extends along the length of the punch  10 . The shaft  42  is rotatable within and at least partially supported by the collar  38  during punching. With reference to  FIG. 5 , a first portion  44  of the collar  38  is integrally formed with the lever  28 , and a second portion  45  is pivotably coupled to the first portion  44  via a connecting pin  41 . This hinged connection between the first portion  44  and the second portion  45  allows the collar  38  to be secured to and removed from the shaft  42  to facilitate changing and moving the punch heads  14  as desired. 
     In the illustrated construction of the punch  10 , the handle  26  is coupled to the shaft  42  via an integral hub  54 . A set screw or a connecting pin  56  is utilized to secure or rotationally fix the handle  26  to the shaft  42 . Alternatively, the handle  26  may be coupled to the shaft  42  in any of a number of different ways, including, among others, integrally forming the handle  26  and the shaft  42 . The shaft  42  is loosely supported within the collars  38  so as to form another pivot  58  (see  FIGS. 6-10 ) of the linkage  64 , via the shaft  42  being allowed to rotate freely within the collars  38 . 
     With reference to  FIGS. 5-10 , the punch  10  includes vertical uprights  46  (only one is shown) coupled to the base  22 . The vertical uprights  46  define a portion of yet another pivot  48  of the linkage  64 . In the illustrated embodiment, each pivot  48  includes an aperture in the form of a radial or an arcuate slot  60  defined in each vertical upright  46  on each side of the punch  10 , and a projection or a pin  52  received within the slot and both rotatably and translationally movable relative to the slot  60 . Alternative constructions of the linkage may include an aperture having any of a number of different configurations, provided that the projection or pin  52  be allowed to both rotate and translate relative to the aperture to define a generally arcuate path of relative movement between the components defining the pivot  48 . Other geometries that provide relative rotation and translation without using apertures and projections can also be substituted (e.g., slider arrangements, channel arrangements, and the like). In yet other embodiments, the path of relative movement between the components defining the pivot need not be arcuate, yet will still allow the relative rotational and translational movement between the components defining the pivot, and ultimately between the links coupled together at the pivot. 
     In the illustrated construction of the linkage  64 , one of the pins  52  is coupled to a collar  50  (see  FIG. 5 ) mounted on one end of the shaft  42 , and the other pin  52  is coupled to the integral hub  54  at the other end of the shaft  42 . During operation of the punch  10 , the handle  26  pivots about the pins  52 , which move within their respective slots  60  along an arcuate path during rotation of the handle  26 . Thus, the pivot  48  is not a typical pivot in which a pin rotates within an aperture configured to permit rotation but to generally prevent any other relative movement of the pin (like the pivots  30  and  58 ), but rather is a movable pivot or a pivot defined by components that undergo relative translational movement. 
     In an alternative construction of the punch  10 , the slot  60  can be defined in structure associated with the handle  26  (e.g., in the hub  54  or collar  50 ) and the pins  52  can be on the vertical uprights  46  or other portions of the base  22 . In other words, the components that define the pivot  48  can be reversed from the illustrated construction without changing the operation of the pivot  48  or the linkage  64 . 
     In yet another alternative construction of the punch  10  and the linkage  64 , the fixed pivot  30  and the moving pivot  48  could be reversed such that the pivot defined between the lever  28  and the base  22  (e.g., via the hinge portion  21  of the punch housing  20 ) could include an aperture and a projection movable relative to the aperture (e.g., in an arcuate path) in the manner discussed above for the pivot  48 . In this case, the pivot  48  could remain as discussed above, or could be a typical pivot with the pins  52  pivoting within an aperture sized to allow substantially only rotation of the pins  52  therein. In yet other alternative applications of the linkage  64 , the pivot  58  could define the movable pivot. Therefore, the illustrated punch  10  provides a linkage  64  for a paper punch including a base member  22  and a drive link member in the form of lever  28  pivotably coupled to the base  22  (e.g., via the hinge portion  21  of the punch housing  20 ) at a first pivot  30 . An input member in the form of handle  26  is pivotably coupled to the drive link (e.g., via the collars  38 ) at a second pivot  58 . The input member or handle  26  is also pivotably coupled to the base  22  (e.g., via vertical uprights  46 ) at a third pivot  48 . At least one of the pivots provides both pivotal (i.e., rotational) and translational movement between the respective members upon movement of the input member. In other embodiments, there could be additional linkage members and additional pivots, however, at least one of the pivots would still provide both pivotal (i.e., rotational) and translational movement between the respective members. 
     With reference to  FIGS. 5-10 , a connecting pin  34  may be used to connect the lever  28  to the punch head  14  such that action upon the lever  28  results in action upon the punch pin  18 . As shown in  FIG. 11 , the punch pin  18  includes an aperture  36  through which the connecting pin  34  is inserted to connect the lever  28  and the punch pin  18 . The lever  28  includes a slot  33  in which the connecting pin  34  slides when the lever  28  is rocked or pivoted about pivot  30 . The sliding contact between the connecting pin  34  and the slot  33  helps to maintain the application of force to the punch pin  18  at a known point and in the required direction. The purpose of such sliding contact is distinct from the sliding contact that may occur at the pivot  48  in the linkage  64 , which is not to apply a consistently directed force to an output member, but rather is to create an improved linkage pivot that can eliminate a physical link and its associated physical pivot, while simulating the motion of the linkage as if that physical link and its associated physical pivot were not eliminated. 
       FIG. 11  schematically illustrates the linkage  64  of the invention in terms of a force diagram that will be understood by one of skill in the art to represent a four bar linkage. Thus, the “bars” defined below do not necessarily relate to a physical structure, but rather refer to the “bars” of the linkage in the force diagram. The drive linkage  64  includes a first bar  68  that extends between the pivot  58  and the fixed pivot  30 . In the illustrated punch  10 , this first bar is the lever  28 . A second bar  72  extends between the pivot  58  and the pivot  48 . In the illustrated punch  10 , this second bar  72  is defined by the hub  54  and collar  50 . A fixed or ground bar  76  extends between the pivot  30  and a fixed point  80 , as shown in  FIG. 11 . This fixed point  80  defines the center of rotation of the arc defined by the arcuate slot  60 . There is no physical link associated with the ground bar  76  except for the inherent structure and strength of the base  22 . Furthermore, there is no physical link associated with a third bar  84  extending between the fixed point  80  and the pivot  48 . Instead, the configuration of the pivot  48  (i.e., its ability to translate in addition to rotate), and the strong construction of the punch  10  components allows the linkage  64  to function in a similar manner to a four bar linkage, but allows eliminating a physical link and a physical pivot typically associated with a four bar linkage. By eliminating this physical link and physical pivot, there is greater flexibility in configuring the punch, but the mechanical advantage obtained with a four bar linkage is maintained. 
       FIGS. 7-10  illustrate the relative motion of the components discussed above as the punch is actuated. For discussion purposes, motion from left to right will be discussed below from the perspective of the punch as viewed in  FIGS. 7-10 .  FIG. 7  illustrates the punch  10  in the rest position. In the rest position, the first bar  68  is located to the left of the second bar  72 , and the second bar  72  forms an obtuse angle with respect to the eliminated third bar  84 . 
     As the handle  26  is rotated, as shown in  FIG. 8 , the shaft  42  rotates with the hub  54  and collar  50  such that the second bar  72  is now substantially vertical, and the first bar  68  (i.e., the lever  28 ) moves to the right of the second bar  72 . The motion of the lever  28  due to rotation of the handle  26  and the fixed position of the pivot point  30  moves the connecting pin  34  and the punch pin  18  out of the punch housing  20  toward the slot  12 . The pivot pin  52  begins to translate (i.e., slide) up the slot  60 , while also rotating within the slot  60 . 
     As shown in  FIG. 9 , continued rotation of the handle  26  moves the lever  28  such that the lever  28 , and thus the first bar  68 , are substantially vertical. The pivot pin  52  slides further in the slot  60 , while also rotating, and the second bar  72  forms an acute angle with respect to the invisible bar  84 . The punch pin  18  continues to move into the slot  12 . As the handle  26  reaches the bottom of its rotational path, shown in  FIG. 10 , the pivot pin  52  has reached the uppermost point of travel within the slot  60 . The punch pin  18  is fully extended through the slot  12  and through apertures in the receiving member  24 . When paper is punched by the punch pin  18 , the pieces of paper punched out of the sheet, commonly called chads, fall into a collection space between the receiving member  24  and the removable cover  25 . 
     As the user releases the handle  26 , a spring (not shown) seated in a groove  88  (see  FIG. 8 ) in the punch pin  18  biases the punch pin  18  against the lever  28 . The bias of the spring, through the drive linkage  64 , returns the punch  10  to the rest position. In cases of a jam, the handle  26  can be manually lifted to move the punch pin  18 , and thus the other punch components, back to rest. 
       FIGS. 12-15  illustrate a stapler  200  incorporating an embodiment of the improved drive linkage  204  of the present invention. The illustrated stapler  200  is a manually-activated, potential energy style stapler of the type generally described in pending U.S. application Ser. No. 11/424,618, filed Jun. 16, 2006, the entire content of which is hereby incorporated by reference (hereinafter the &#39;618 application). For clarity in viewing the drive linkage  204 , some internal structure of the stapler  200  has been removed. However, it is understood that the linkage  204  of the present invention can also be incorporated for use in other potential energy style staplers, in non-potential energy style staplers, and in electric staplers driven by an electric motor or a solenoid. 
     The stapler  200  includes a body portion that, for the purposes of consistency with the above discussion of the linkage  64  used in the punch  10 , will be referred to hereinafter as the base  208 . The base  208  includes the magazine  210  that houses the staples. 
     A drive link  214  is pivotably connected to the base  208  at pivot  218 . In the illustrated stapler  200 , bosses or a pin  222  (i.e., a projection) on the base  208  are received in an aperture  226  (see  FIG. 15 ) on the drive link  214  to define the pivot  218 . Alternatively, the bosses or pin  222  could be on the drive link  214  and the apertures could be formed in the base  208 . The illustrated pivot  218  is a typical pivot in that the bosses or pin  222  are allowed to rotate in the aperture  226 , but cannot substantially translate or otherwise move relative to the aperture  226 . The drive link  214  supports a spring  230  that is deflected during stapler operation to store energy. An end of the spring is slidably received in an aperture  232  in the staple driver  234  so that when the stored energy in the spring  230  is released, the driver  234  is moved downwardly to drive a staple from the base  208 . The details of the energy storage and energy release with the spring  230  are fully described in the &#39;618 application and need not be described here in detail. Only the construction and operation of the linkage  204  is discussed in detail herein. 
     The stapler  200  further includes a cover  238  acting as the input member of the linkage  204 . The cover  238  is pivotably coupled to the drive link  214  at pivot  242 . Any suitable arrangement can be used to achieve the pivot  242 , such as bosses or a pin  246  in one of the cover  238  and the drive link  214  being received in an aperture or apertures  250  in the other of the cover  238  and the drive link  214 . Like the pivot  218 , the illustrated pivot  242  is a typical pivot in that the bosses or pin  246  are allowed to rotate in the aperture  250 , but cannot substantially translate or otherwise move relative to the aperture  250 . 
     The cover  238  is also pivotably coupled with the base  208  at pivot  254 . In the illustrated stapler  200 , the pivot  254  is defined in part by one or more apertures in the form of radial or arcuate slots  258  formed in or with a portion of the cover  238 . Bosses or a pin  262  on the base  208  are received in the slots and are both rotatably and translationally movable relative to the slots  258 . As shown in  FIGS. 12-14 , the bosses or pin  262  are fixed relative to the base  208  and movement of the handle  238  causes the slots  258  to move along an arcuate path relative to the bosses or pin  262  as the handle  238  is depressed. Alternative constructions of the linkage  204  may include an aperture having any of a number of different configurations, provided that the bosses or pin  262  be allowed to both rotate and translate relative to the aperture to define a generally arcuate path of relative movement between the components defining the pivot  254 . Other geometries that provide relative rotation and translation without using apertures and projections can also be substituted (e.g., slider arrangements, channel arrangements, and the like). In yet other embodiments, the path of relative movement between the components defining the pivot need not be arcuate, yet will still allow the relative rotational and translational movement between the components defining the pivot, and ultimately between the links coupled together at the pivot. Thus, the pivot  254  is not a typical pivot in which a pin or boss rotates within an aperture configured to permit rotation but to generally prevent any other relative movement of the pin or boss (like the pivots  218  and  242 ), but rather is a movable pivot or a pivot defined by components that undergo relative translational movement. 
     In an alternative construction of the stapler  200 , the slots  258  can be defined in structure associated with the base  208  and the bosses or pin  262  can be on the handle  238 . In other words, the components that define the pivot  254  can be reversed from the illustrated construction without changing the operation of the pivot  254  or the linkage  204 . 
     In yet another alternative construction of the stapler  200  and the linkage  204 , the fixed pivot  218  and the moving pivot  254  could be reversed such that the pivot defined between the drive link  214  and the base  208  could include an aperture and a projection movable relative to the aperture (e.g., in an arcuate path) in the manner discussed above for the pivot  254 . In this case, the pivot  254  could remain as discussed above, or could be a typical pivot with the bosses or pin  262  pivoting within an aperture sized to allow only rotation of the bosses or pin  262  therein. In yet other alternative applications of the linkage  204 , the pivot  242  could define the movable pivot. Therefore, the illustrated stapler  200  provides a linkage  204  for a stapler including a base member  208  and a drive link member  214  pivotably coupled to the base member  208  at a first pivot  218 . An input member in the form of cover  238  is pivotably coupled to the drive link member  214  at a second pivot  242 . The input member or cover  238  is also pivotably coupled to the base member  208  at a third pivot  254 . At least one of the pivots provides both pivotal (i.e., rotational) and translational movement between the respective members upon movement of the input member. In other embodiments, there could be additional linkage members and additional pivots, however, at least one of the pivots would still provide both pivotal (i.e., rotational) and translational movement between the respective members. 
     The sliding contact between the spring  230  on the drive link  214  and the aperture  232  in the driver  234  helps to maintain the application of force to the driver  234  at a known point and in the required direction. The purpose of such sliding contact is distinct from the sliding contact that may occur at the pivot  254  in the linkage  204 , which is not to apply a consistently directed force to an output member, but rather is to create an improved linkage pivot that can eliminate a physical link and its associated physical pivot, while simulating the motion of the linkage as if that physical link and its associated physical pivot were not eliminated. 
       FIG. 15  schematically illustrates the linkage  204  of the invention in terms of a force diagram that will be understood by one of skill in the art to represent a four bar linkage. Thus, the “bars” defined below do not necessarily relate to a physical structure, but rather refer to the “bars” of the linkage in the force diagram. The drive linkage  204  includes a first bar  268  that extends between the pivot  242  and the fixed pivot  218 . In the illustrated stapler  200 , this first bar is the drive link  214 . A second bar  272  extends between the pivot  242  and the pivot  254 . In the illustrated stapler  200 , this second bar  272  is defined by structure of the cover  238 . A fixed or ground bar  276  extends between the pivot  218  and a fixed point  280 , as shown in  FIG. 15 . This fixed point  280  defines the center of rotation of the arc defined by the arcuate slots  258 . There is no physical link associated with the ground bar  276  except for the inherent structure and strength of the base  208 . Furthermore, there is no physical link associated with a third bar  284  extending between the fixed point  280  and the pivot  254 . Instead, the configuration of the pivot  254  (i.e., its ability to translate in addition to rotate), and the strong construction of the stapler  200  components allows the linkage  204  to function in a similar manner to a four bar linkage, but allows eliminating a physical link and a physical pivot typically associated with a four bar linkage. By eliminating this physical link and physical pivot, there is greater flexibility in configuring the stapler, but the mechanical advantage obtained with a four bar linkage is maintained. 
     The linkage  204  operates in a similar manner to the linkage  64  discussed above with respect to punch  10 . Therefore, the operation of the linkage  204  will not be described in further detail. 
     The stapler  200  further includes an anvil plate  288  pivotably coupled to the base  208 . This anvil plate  288  includes an anvil for bending the legs of the staples, as is well known in the art. The anvil plate  288  can include an overmolded or otherwise-applied surround (not shown) to complete the stapler. In the illustrated stapler  200 , the anvil plate  288  and any surrounding structure is not part of the drive linkage  204 . 
     Various features of the invention are set forth in the following claims.