Abstract:
A folding knife having a handle, a pivoting blade guard, and a pivoting blade. Both the guard and the blade pivot on a common pivot pin that is secured to or within the handle. Both the handle and the guard feature at least one arcuate slot that extends in an arc around the pivot pin. A tang pin located in the tang of the blade rides in the arcuate slots and serves as a stop for both the handle and the guard, limiting the range of their rotation on the pivot pin.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention is directed generally to a folding knife. More specifically, the present invention is directed to a folding knife having a pivoting blade and a pivoting blade guard. 
   2. Description of Related Art 
   Typically, folding knives are knifes with at least one blade that is pivotably connected to a single handle. The blade generally pivots 180° between a closed position, wherein the blade is located within a groove in the handle, and an opened position, wherein the blade typically extends from the handle. 
   A Balison, sometimes called a Butterfly knife or a Batangas knife, is a type of folding knife that includes a single blade pivotably connected to two handle halves. The handle halves each rotate around the blade such that, when closed, the blade is concealed within grooves in the handle halves, and when opened, the blade extends from both of the handle halves. Because of the construction of the Balisong, the Balisong can quickly be manipulated, or flipped, from a closed to an opened position using one hand. 
   SUMMARY OF THE INVENTION 
   However, in the case of both the traditional folding knife and the Balisong, as the blade transitions between a closed position and an opened position, the blade is exposed and can cause injury to the user. Likewise, when the blade transitions between an opened position and a closed position, the blade is again exposed. 
   This invention relates generally to a folding knife. More specifically, the present invention is directed to a folding knife having a pivoting blade and a pivoting blade guard. In various exemplary embodiments, the folding knife of this invention comprises at least some of a handle, a guard, and a blade. 
   Both the guard and the blade pivot on a common pivot pin that is secured to or within the handle. Both the handle and the guard feature at least one arcuate slot that extends in an arc around the pivot pin. A tang pin that is located in the tang of the blade rides in the arcuate slots and serves as a stop for both the handle and the guard, limiting the range of their rotation on the pivot pin. 
   In the closed position, the guard and blade are nested within the handle. To open the folding knife, the guard and blade are rotated together out of the handle. As this occurs, the tang pin travels in the handle&#39;s arcuate slot until it reaches the end of the slot, where it stops and restricts the blade from rotating further. At this point, the guard continues to pivot. As the guard continues to pivot, the guard&#39;s arcuate slot travels around the now stationary tang pin. 
   At the completion of the guard&#39;s arc, the guard&#39;s travel is stopped by the stationary tang pin interacting with the end of the guard&#39;s slot. The tang pin is now locked between the two opposing ends of the arcuate handle slot and the arcuate guard slot. This action locks the blade securely in place. The completion of the guard&#39;s arc also leaves the guard nested within the handle, presenting a single handle unit as a purchase for using the folding knife. The natural grasp of the hand keeps the handle and guard together and secures the locking action of the blade. 
   Reversing this process closes both the guard and the blade safely within the handle. 
   If desired, the guard and handle may be held together in a fully open or fully closed position by means of a spring detent, magnets, or other device. A thumb stud, finger button, or similar purchase point may also be added to the guard to allow easier initiation of the opening process. 
   If constructed of materials of sufficient mass, this design could be quickly and easily manipulated with one hand opening and closing techniques similar to those employed in the use of a Balisong. 
   Accordingly, this invention provides a folding knife, which allows the blade to generally remain protected within a guard as the blade is moving to the opened position. 
   This invention separately provides a folding knife, which allows the blade to generally remain protected within a guard as the blade is moving to the closed position. 
   This invention separately provides a folding knife, which is easily opened or closed with one hand. 
   This invention separately provides a folding knife lock means, which can be easily engaged and disengaged. 
   This invention separately provides a folding knife, which, when in the opened position and grasped in a normal, working manner, locks the blade such that the blade cannot be closed on the user&#39;s fingers. 
   These and other features and advantages of this invention are described in or are apparent from the following detailed description of the exemplary embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The exemplary embodiments of this invention will be described in detail, with reference to the following figures, wherein like reference numerals refer to like parts throughout the several views, and wherein: 
       FIG. 1  shows a perspective view of an exemplary embodiment of a folding knife having a pivoting blade and a pivoting blade guard, according to this indenting, illustrating the knife in the opened position; 
       FIG. 2  shows an exploded perspective view of a first exemplary embodiment of the folding knife according to this invention; 
       FIG. 3A  shows a more detailed perspective view of a portion of the knife handles of the first exemplary embodiment of the folding knife according to this invention; 
       FIG. 3B  shows a more detailed perspective view of a portion of the knife blade and guard of the first exemplary embodiment of the folding knife according to this invention; 
       FIG. 4  shows a partial exploded side elevation view, illustrating the handle, scale, and locking means of the first exemplary embodiment of the folding knife according to this invention; 
       FIG. 5  shows an exploded perspective view of a second exemplary embodiment of the folding knife according to this invention; 
       FIG. 6A  shows a side view of the first exemplary embodiment of the folding knife according to this invention, illustrating the knife in the closed position with the optional lock means engaged; 
       FIG. 6B  shows a side view of the first exemplary embodiment of the folding knife according to this invention, illustrating the optional clock means disengaged and the components of the knife as the knife moves through an opening sequence; 
       FIG. 6C  shows a side view of the first exemplary embodiment of the folding knife according to this invention, illustrating the knife in the opened position with the optional lock means engaged; 
       FIG. 7A  shows a partially-cutaway side view of the first exemplary embodiment of the folding knife according to this invention, illustrating the knife in the closed position; 
       FIG. 7B  shows a partially-cutaway side view of the first exemplary embodiment of the folding knife according to this invention, illustrating the knife in a first exemplary position in the opening sequence; 
       FIG. 7C  shows a partially-cutaway side view of the first exemplary embodiment of the folding knife according to this invention, illustrating the knife in a second exemplary position in the opening sequence; 
       FIG. 7D  shows a partially-cutaway side view of the first exemplary embodiment of the folding knife according to this invention, illustrating the knife in a third exemplary position in the opening sequence; 
       FIG. 7E  shows a partially-cutaway side view of the first exemplary embodiment of the folding knife according to this invention, illustrating the knife in a fourth exemplary position in the opening sequence; and 
       FIG. 7F  shows a partially-cutaway side view of the first exemplary embodiment of the folding knife according to this invention, illustrating the knife in the opened position. 
   

   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
   For simplicity and clarification, the design factors and operating principles of the folding knife according to this invention are explained with reference to various exemplary embodiments of the folding knife according to this invention. The basic explanation of the design factors and operating principles of the folding knife of this invention is applicable for the understanding, design, and operation of the folding knife of this invention. 
   It should also be appreciated that the term “knife” is used for basic explanation and understanding of the operation of the systems, methods, and apparatuses of this invention. Therefore, the term “knife” is not to be construed as limiting the systems, methods, apparatuses, or applications of this invention. 
   It should also be appreciated that while this invention is described and shown as a folding knife having a knife blade and knife blade guard that rotate with respect to a handle, in various exemplary, contemplated embodiments, the knife blade may be replaced by another instrument, implement, or tool portion having a working portion, such as, for example, screwdriver, a pen, pencil, or other marking device, one or more keys, a saw blade, or any other instrument, implement, or tool, while still employing the design factors and operating principles of this invention, thus forming a folding implement. 
   Turning now to the drawings FIGS. as illustrated in  FIGS. 1 and 2 , the exemplary folding knife  100  comprises at least some of a blade  110 , a guard  120 , a handle  130 , and handle scales  141  and  141 ′. In various exemplary, non-limiting embodiments, the folding knife  100  may also include a lock means  170 . 
   As illustrated in  FIG. 2 , the blade  110  includes a sharpened portion  111  and a tang portion  113 . In various exemplary embodiments, the sharpened portion  111  may include one or more cutting edges and may terminate in an edge or point. The cutting edge(s) may include serrated portions. Alternatively, the sharpened portion  111  may not be sharpened such that the folding knife  100  may be used as a training or practice knife. 
   A blade pivot pin aperture  112  and a blade tang pin aperture  116  are formed in the tang portion  113  of the blade  110 . The blade pivot pin aperture  112  is sized to allow the blade  110  to pivot around a sleeve portion  152  of a pivot pin  150 . The blade tang pin aperture  116  is formed to accept a tang pin  118 . 
   The guard  120  comprises a first guard plate  121  and a second guard plate  121 ′. In various exemplary embodiments, the first guard plate  121  and the second guard plate  121 ′ have identical or substantially identical shaping and dimensioning and are substantially identical in planform. The first guard plate  121  includes a guard pivot pin aperture  122  formed proximate a pivot end of the first guard plate  121 . The guard pivot pin aperture  122  is sized to allow the first guard plate  121  to pivot around the sleeve portion  152  of the pivot pin  150 . 
   An arcuate guard slot  124  is formed in the first guard plate  121 , concentric to the guard pivot pin aperture  122 , and positioned to be aligned with the blade tang pin aperture  116 . 
   In various exemplary embodiments, the second guard plate  121 ′ also includes a guard pivot pin aperture  122 ′ formed proximate a pivot end of the second guard plate  121 ′. As with the guard pivot pin aperture  122 , the guard pivot pin aperture  122 ′ is sized to allow the second guard plate  121 ′ to pivot around the pivot pin  150 . 
   An arcuate guard slot  124 ′ is formed in the second guard plate  121 ′, concentric to the guard pivot pin aperture  122 ′, and positioned to be aligned with the blade tang pin aperture  116 . 
   The first guard plate  121  and the second guard plate  121 ′ are coupled together, proximate a free end of the first guard plate  121  and the second guard plate  121 ′, via guard coupling means  128 , to form the generally “U” shaped guard  120 . In various exemplary embodiments, the guard coupling means  128  comprise one or more rivets that are used to join the first guard plate  121  and the second guard plate  121 ′. However, it should be appreciated that, in various exemplary embodiments, the guard coupling means  128  may comprise screws, welded bars, bars coupled by adhesives, or any other means for permanently or releasably coupling or joining the first guard plate  121  to the second guard plate  121 ′. Alternatively, the guard  120  may be formed as one continuous component, wherein the first guard plate  121 , the coupling means  128 , and the second guard plate  121 ′ are formed as one unit or component. 
   When the first guard plate  121  and the second guard plate  121 ′ are coupled together, if necessary, the first guard plate  121  and the second guard plate  121 ′ are substantially parallel and spaced apart to define a blade storage area between the first guard plate  121  and the second guard plate  121 ′. The blade storage area is appropriately sized to allow at least the sharpened portion  111  of the blade  110  to be pivoted into and/or out of the blade storage area. 
   The handle  130  comprises a first handle plate  131  and a second handle plate  131 ′. In various exemplary embodiments, the first handle plate  131  and the second handle plate  131 ′ have identical or substantially identical shaping and dimensioning and are substantially identical in planform. The first handl plate  131  includes a handle pivot pin aperture  132  formed proximate a pivot end of the first handle plate  131 . The handle pivot pin aperture  132  is sized to accept the sleeve portion  152 , or any other appropriate portion, of the pivot pin  150 . 
   An arcuate handle slot  134  is formed in the first handle plate  131 , concentric to the handle pivot pin aperture  132 , and positioned to be aligned with the blade tang pin aperture  116 . 
   In various exemplary embodiments, the second handle plate  131 ′ also includes a handle pivot pin aperture  132 ′ formed proximate a pivot end of the second handle plate  131 ′. As with the handle pivot pin aperture  132 , the handle pivot pin aperture  132 ′ is sized to accept the sleeve portion  152 , or any other appropriate portion, of the pivot pin  150 . 
   An arcuate handle slot  134 ′ is formed in the second handle plate  131 ′, concentric to the handle pivot pin aperture  132 ′, and positioned to be aligned with the blade tang pin aperture  116 . 
   The first handle plate  131  and the second handle plate  131 ′ are coupled together, proximate a free end of the first handle plate  131  and the second handle plate  131 ′, via handle coupling means  138 , to form the generally “U” shaped handle  130 . In various exemplary embodiments, the handle coupling means  138  comprise one or more rivets that are used to join the first handle plate  131  and the second handle plate  131 ′. However, it should be appreciated that, in various exemplary embodiments, the handle coupling means  138  may comprise screws, welded bars, bars held by an adhesive, or any other means for permanently or releasably coupling or joining the first handle plate  131  to the second handle plate  131 ′. Alternatively, the handle  130  may be formed as one continuous component, wherein the first handle plate  131 , the coupling means  138 , and the second handle plate  131 ′ are formed as one unit or component. In still other exemplary embodiments, one or more of the first handle plate  131  and the second handle plate  131 ′ may be skeletonized or comprise a more cylindrical profile. 
   When the first handle plate  131  and the second handle plate  131 ′ are coupled together, if necessary, the first handle plate  131  and the second handle plate  131 ′ are substantially parallel and spaced apart to define a guard storage area between the first handle plate  131  and the second handle plate  131 ′. The guard storage area is appropriately sized to allow the guard  120  to be pivoted into and/or out of the guard storage area. 
   To form the folding knife  100 , the guard  120  is positioned within the guard storage area of the handle  130  and the blade  110  is positioned within the blade storage area of the guard  120  such that the blade pivot pin aperture  112 , the guard pivot pin apertures  122  and  122 ′, and the handle pivot pin apertures  132  and  132 ′ are aligned. 
   When the guard  120 , the handle  130 , and the blade  110  are appropriately aligned, the tang pin  118  is positioned within the aligned arcuate handle slots  134  and  134 ′, the aligned arcuate guard slots  124  and  124 ′, and the aligned blade tang pin aperture  116 . In this manner, the angular rotation of the guard  120  and the blade  110 , in relation to the handle  130 , are restricted to the degree of angular rotation allowed by the respective arcuate slots. 
   When the tang pin  118  is positioned, the handle scales  141  and  141 ′ are coupled in overlying relationship with an outer surface of the first handle plate  131  and the second handle plate  131 ′, respectively. In various exemplary embodiments, the handle scales  141  and  141 ′ have identical or substantially identical shaping and dimensioning and are substantially identical in planform to the first handle plate  131  and the second handle plate  131 ′, respectively. 
   In various exemplary embodiments, the handle scales  141  and  141 ′ each include a scale pivot pin aperture  142  and  142 ′, formed to align with the handle pivot pin apertures  132  and  132 ′, respectively. In various exemplary embodiments, the scale pivot pin apertures  142  and  142 ′ are sized to accept the sleeve portion  152 , or any other appropriate portion, of the pivot pin  150 . Alternatively, the scale pivot pin apertures  142  and  142 ′ may each be sized to accept at least a portion of the enlarged head portion  154  or  156  of the pivot pin  150  so that the enlarged head portions  154  and  156  may be recessed or partially recessed within at least a portion of the handle scales  141  and  141 ′. 
   In various exemplary embodiments, the handle scales  141  and  141 ′ may be formed of G-10, a plastic, a metal, a composite, or any other suitable material. In still other exemplary embodiments, one or more of the handle scales  141  and  141 ′ may be skeletonized or comprise a more cylindrical profile. 
   The handle scales  141  and  141 ′ may be attached, coupled, or joined to the handle plates  131  and  131 ′, via, for example, scale attachment means  148 . In various exemplary embodiments, as shown herein, a scale attachment means  148  may comprise one or more bolts that are used to join the first handle scale  141  to the first handle plate  131  and the second handle scale  141 ′ to the second handle plate  131 ′. Alternatively, the handle scales  141  and  141 ′ may be attached or coupled to the handle plate  131  and  131 ′, via rivets, screws, adhesives, welding, or any other means of methods for permanently or releasably attaching, coupling, or joining the handle scales  141  and  141 ′ to the handle plates  131  and  131 ′. 
   In various exemplary embodiments, the handle scales  141  and  141 ′ are attached, coupled, or joined to the handle plates  131  and  131 ′ in order to, among other things, maintain the tang pin  118  in place. However, in various alternative embodiments, the arcuate handle slot  134  and the arcuate handle slot  134 ′ may be formed up mere recesses and the first handle plate  131  and the second handle plate  131 ′, which do not extend completely through the handle plates  131  and  131 ′. In these embodiments, the tang pin  118  may be maintained in place by the handle plates  131  and  131 ′ and the handle scales  141  and  141 ′ may be optional. 
   As illustrated herein, the tang pin  118  comprises a pin or rod that is removable positioned within the blade tang pin aperture  116 . Alternatively, the tang and  118  may be secured within the blade tang and aperture  116 . In still other embodiments, the tang pin  118  may comprise one or more appropriately sized protrusions that extend from the tang portion  113  of the blade  110 . In these exemplary embodiments, the tang pin  118  is formed as an integral part of the blade  110 . 
   To maintain the blade  110 , the guard  120 , the handle  130 , and the handle scales  141  and  141 ′, if included, in an appropriately assembled relationship, the pivot pin  150  is extended through the aligned blade pivot pin aperture  112 , guard pivot pin apertures  122  and  122 ′, handle pivot pin apertures  132  and  132 ′, and scale pivot pin apertures  142  and  142 ′ and secured in place. 
   In various exemplary embodiments, as shown herein, the pivot pin  150  includes two components, an internally threaded sleeve portion  152  having an enlarged head portion  154 , and an externally threaded bolt portion  156 , also having an enlarged head portion  158 . The blade pivot pin aperture  112 , the guard pivot pin apertures  122  and  122 ′, and the handle pivot pin apertures  132  and  132 ′ are all sized to accept the sleeve portion  152 , or any other appropriate portion, of the pivot pin  150 . While the handle pivot pin apertures  132  and  132 ′ may be sized to accept the sleeve portion  152 , or any other appropriate portion, of the pivot pin  150  in a relatively tight, friction fit, the blade pivot pin aperture  112  and the guard pivot pin apertures  122  and  122 ′ are sized to allow the blade  110  and the guard  120  to pivot relatively freely, about the sleeve portion  152  of the pivot pin  150 . 
   Generally, the bolt portion  156  of the pivot pin  150  is shorter than the internally threaded portion of the sleeve portion  152 , such that the bolt portion  156  can be threaded into the sleeve portion  152  until a free end of the sleeve portion  152  contacts the underside of the head portion  158  of the bolt portion  156 . In this manner, the amount of compression between the handle  130 , the guard  120 , and blade  110  can be limited by the length of the sleeve portion  152  of the pivot pin  150 . 
   While a specific version of the pivot pin  150  is described and shown herein, it should be appreciated that the pivot pin  150  may be replaced by, for example a rivet, bushing, rolling pin, bearing, or any other known or later developed device capable of securing the handle  130 , the guard  120 , and blade  110  together while allowing the guard  120  in the blade  110  to pivot as described herein. In certain exemplary embodiments, the pivot pin  150  may have a larger diameter portion, for example, in the area of one or both of the blade  110  and the first guard plate  121  and the second guard plate  121 ′, and smaller diameter portion (i.e., a stepped down shoulder portion), for example, in the area of one or both of the first handle plate  131  and the second handle plate  131 ′. 
   Thus, when the folding knife  100  is assembled, the blade  100  is pivotably coupled, via the pivot pin  150 , between the first guard plate  121  and the second guard plate  121 ′ of the guard  120 , and the guard  120  is pivotably coupled, via the pivot pin  150 , between the first handle plate  131  and the second handle plate  131 ′ of the handle  130 . In this assembled relationship, with the tang pin  118  positioned within the aligned blade tang pin aperture  116 , arcuate guard slots  124  and  124 ′, and arcuate handle slots  134  and  134 ′, the blade  110  is able to rotate, in relation to the guard  120  and the handle  130 , within a limited arc of motion as defined by the interaction of the tang pin  118  and the arcuate slots  124 ,  124 ′,  134 , and  134 ′. Likewise, the guard  120  is able to rotate, in relation to the blade  110  and the handle  130 , within a limited arc of motion as defined by the interaction of the tang pin  118  and the arcuate slots  124 ,  124 ′,  134 , and  134 ′. 
   In various exemplary embodiments, the arcuate guard slots  124  and  124 ′ are formed so as to limit the arc of motion of the guard  120  such that the guard  120  is capable of rotating between a position wherein a longitudinal axis of the guard  120  is aligned with a longitudinal axis of the blade  110  and the blade  110  is within the blade storage area of the guard  120  (as illustrated in FIGS.  3 B and  7 A- 7 C) and a position wherein the longitudinal axis of the guard  120  is aligned with the longitudinal axis of the blade  110  and the blade  110  is outside of the blade storage area of the guard  120  (as illustrated in  FIGS. 1 ,  6 C, and  7 F). In various exemplary embodiments, the arc of motion of the guard  120  is 180°, as measured between the longitudinal axis of the guard  120  and the longitudinal axis of the blade  110 . 
   Likewise, in various exemplary embodiments, the arcuate handle slots  134  and  134 ′ are formed so as to limit the arc of motion of the blade  110  such that the blade  110  is capable of rotating between a position wherein a longitudinal axis of the handle  130  is aligned with a longitudinal axis of the blade  110  and the blade  110  is within the guard storage area of the handle (as illustrated in  FIGS. 6A and 7A ) and a position wherein the longitudinal axis of the handle  130  is aligned with the longitudinal axis of the blade  110  and the blade  110  is outside of the guard storage area of the handle  130  (as illustrated in  FIGS. 1 ,  6 C, and  7 D- 7 F). In various exemplary embodiments, the arc of motion of the blade  110  is 180°, as measured between the longitudinal axis of the handle  130  and the longitudinal axis of the blade  110 . 
   In various exemplary embodiments, the extreme, or terminal ends of the arcuate guard slots  124 ,  124 ′,  134 , and  134 ′ are reinforced so as not to be worn away or deformed, over time, by the interaction of the tang pin  118  and the terminal ends of the arcuate guard slots  124 ,  124 ′,  134 , and  134 ′. 
   In various exemplary embodiments, one or more washers  160  are included between adjacent sides of the handle  130 , the guard  120 , and the blade  110  to maintain the handle  130 , the guard  120 , and the blade  110  in an appropriately spaced apart relationship. In various exemplary embodiments, the washers  160  may also reduce the amount of friction between the handle  130 , the guard  120 , and the blade  110  during the opening and closing sequences. 
   Alternatively, one or more bosses or raised surfaces (not shown) are included on the mating surfaces of the handle  130 , the guard  120 , and the blade  110  to maintain the handle  130 , the guard  120 , and the blade  110  in an appropriately spaced apart relationship. In various exemplary embodiments, the bosses or raised surfaces (not shown) may also reduce the amount of friction between the handle  130 , the guard  120 , and the blade  110  during the opening and closing sequences. 
   As further illustrated in  FIG. 2 , the folding knife  100  includes an optional lock means  170 . In various exemplary, non-limiting embodiments, the optional lock means  170  includes at least some of a first shuttle bar  171  coupled, via a lock bar  172 , to a second shuttle bar  171 ′. The first shuttle bar  171  and the second shuttle bar  171 ′ are coupled together, proximate a free end of the first shuttle bar  171  and the second shuttle bar  171 ′, via the lock bar  172 , to form the generally “U” shaped locking means  170 . In various exemplary embodiments, the locking means  170  may be formed as one continuous component, wherein the first shuttle bar  171 , the lock bar  172 , and the second shuttle bar  171 ′ are formed as one unit or component. 
   When the first shuttle bar  171  and the second shuttle bar  171 ′ are coupled together, if necessary, the first shuttle bar  171  and the second shuttle bar  171 ′ are substantially parallel and spaced apart to slidably overlap the handle  130  and allow the lock bar  172  to travel within the handle lock bar key ways  139  and  139 ′. As shown herein, the handle lock bar key ways  139  and  139 ′ are appropriately sized grooves formed in the free end of the handle  130 . The handle lock bar key ways  139  and  139 ′ are of a sufficient depth to allow the lock means  170  to slidably move from an outer, or unlocked, position (designated “U” in  FIG. 5 ) to an inner, or locked, position (designated “L” in  FIG. 5 ). 
   In various exemplary embodiments, the lock means  170  includes the lock bar  172  and only one of the first shuttle bar  171  or the second shuttle bar  171 ′. Thus, the lock means  170  may comprise a substantially “L” shaped piece with the lock bar  172  project from one side. 
   Additionally, the lock bar  172  may be formed of a substantially round bar, as illustrated herein, or may comprise a substantially triangular bar, which is capable of engaging substantially “V” shaped handle lock bar key ways  139  and  139 ′ and guard lock bar seats  129  and  129 ′. 
   In various exemplary embodiments, particularly if the lock means is spring biased to the closed position, the lock bar  172  would automatically lock the guard  120  when the guard  120  is in the opened or the closed position. 
   As also shown herein, and guard lock bar seats  129  and  129 ′ are appropriately sized grooves formed in the free end of the guard  120 . The guard lock bar seats  129  and  129 ′ are of a sufficient depth to allow the lock means  170  to be captured within, or engage, the guard lock bar seats  129  and  129 ′ when the lock means  170  is in the inner, or locked, position, and allow the lock means  170  to be free from, or disengage, the guard lock bar seats  129  and  129 ′ when the lock means  170  is in the outer, or unlocked, position. 
   In various exemplary embodiments, the lock means  170  is maintained in the slidably overlapping position with the handle  130  by a shuttle channel (not shown) formed in handle scale  141  and a shuttle channel  147 ′ formed in handle scale  141 ′. 
   The lock means  170  further includes at least one finger button  175  and/or  175 ′ form of bar attached to the first shuttle bar  171  and/or the second shuttle bar  171 ′, respectively. The finger buttons  175  and  175 ′ extend through finger button apertures  146  and  146 ′ formed in the handle scales  141  and  141 ′, respectively, such that the lock means  170  may be manipulated by a user, via the finger buttons  175  and/or  175 ′. 
   Thus, when the handle  130  and the guard  120  are aligned, whether the folding knife  100  is in the closed position, as illustrated in  FIG. 6A  or the opened position, as illustrated in  FIG. 6C , the lock means  170  may be engaged to lock the guard  120  in position within the handle  130 , thereby locking the folding knife  100  and either the closed or the opened position. 
   In various exemplary embodiments, the lock means  170  is maintained in either the lock or unlock position by means of a friction fit between the lock means  170  and the handle  130  or the handle scales  141  and/or  141 ′. Alternatively, the lock means  170  may be maintained in the locked or unlocked position by means of corresponding mating surfaces, such as, for example, a corresponding protrusion and detent, a ball and detent, or a spring biasing device. 
   In various exemplary embodiments, the lock means  170  may comprise a spring detent, one or more magnets, or other similar device. 
     FIG. 5  shows an exploded perspective view of a second exemplary embodiment of the folding knife according to this invention. As shown in  FIG. 5 , the folding knife  200  comprises at least some of a blade  200  comprising a sharpened portion  211 , a blade pivot pin aperture  212 , a tang portion  213 , and a blade tang pin aperture  216 ; a tang pin  218 ; a guard  220  comprising a first guard plate  221  having a guard pivot pin aperture  22 , an arcuate guard slot  224 , and optionally a guard lock bar seat  229  coupled, via a guard coupling means  228 , to a second guard plate  221 ′ having a guard pivot pin aperture  222 ′ and optionally a guard lock bar seat  229 ′; a handle  230  comprising a first handle plate  231  having a handle pivot pin aperture  232 , an arcuate handle slot  234 , and optionally a handle lock bar key way  239  coupled, via a handle coupling means  238 , to a second handle plate  231 ′ having a handle pivot pin aperture  232 ′ and optionally a handle lock bar key way  239 ′; a first handle scale  241  having a first scale pivot pin aperture  242 , and optionally a finger button aperture  246  and a shuttle channel (not shown); a second handle scale  241 ′ having a second scale pivot pin aperture  242 ′, and optionally a finger button aperture  246 ′ and a shuttle channel  247  ′ the first and second handle scales  241  and  241 ′ being attached, coupled or joined to the handle plates  231  and  231 ′, via, for example, scale attachment means  248 ″; a pivot pin  250  comprising an internally threaded sleeve portion  252  having an enlarged head portion  254  and an externally threaded bolt portion  256  having an enlarged head portion  258 ; one or more optional washers  260 ; and optional lock means  270  comprising a first shuttle bar  271  having an optional finger button  275 , coupled, via a lock bar  272 , to a second shuttle bar  271 ′ having an optional finger button  275 ′. 
   It should be understood that each of these elements, if included, correspond to and operate similarly to the blade  110 , the sharpened portion  111 , the blade pivot pin aperture  112 , the tang portion  113 , the blade tang pin aperture  116 , the tang pin  118 , the guard  120 , the first guard plate  121 , the guard pivot pin aperture  122 , the arcuate guard slot  124 , the optional guard lock bar seat  129 , the guard coupling means  128 , the second guard plate  121 ′, the guard pivot pin aperture  122 ′, the optional guard lock bar seat  129 ′, the handle  130 , the first handle plate  131 , the handle pivot pin aperture  132 , the arcuate handle slot  134 , the optional handle lock bar key way  139 , the handle coupling means  138 , the second handle plate  131 ′, the handle pivot pin aperture  132 ′, the optional handle lock bar key way  139 ′, the first handle scale  141 , the first scale pivot pin aperture  142 , the optional finger button aperture  146  and the shuttle channel (not shown), the second handle scale  141 ′, the second scale pivot pin aperture  142 ′, the optional finger button aperture  146 ′ and the shuttle channel  147 ′, the pivot pin  150 , the internally threaded sleeve portion  152  having the enlarged head portion  154 , the externally threaded bolt portion  156  having the enlarged head portion  158 , the one or more optional washers  160 , the optional lock means  170 , the first shuttle bar  171 , the optional finger button  175 , the lock bar  172 , the second shuttle bar  171 ′, and the optional finger button  175 ′, as described above with reference to  FIGS. 1-4 . 
   However, as shown in  FIG. 5 , the second guard plate  221 ′ does not include an arcuate guard slot, the second handle plate  131 ′ does not include an arcuate handle slot, and the tang pin  218  is approximately half the length of the tang pin  118 . Thus, as illustrated in  FIG. 5 , when the folding knife  200  is assembled, the tang pin  218  is positioned within the aligned blade tang pin aperture  216 , the arcuate guard slot  224 , and the arcuate handle slot  234 . In this manner, the blade  210  is able to rotate, in relation to the guard  220  and the handle  230 , within a limited arc of motion as defined by the interaction of the tang pin  218  and the guard slots  224  and  234 . Likewise, the guard  220  is able to rotate, in relation to the blade  210  and the handle  230 , within a limited arc of motion as defined by the interaction of the tang pin  218  and the arcuate slot  224  and  234 . 
   While  FIG. 5  shows the second guard plate  221 ′ without an arcuate guard slot and the second handle plate  131 ′ without an arcuate handle slot, it should be appreciated that the arcuate guard slot and the arcuate handle slot may be for removed from either the first guard plate  221  and the first handle plate  131  or the second guard plate  221 ′ and the second handle plate  131 ′. 
     FIGS. 6A through 6C  show side views of the folding knife  100 , illustrating the knife  100  in the closed position, as the knife  100  moves through an opening sequence, and in the opened position.  FIGS. 7A through 7F  show partially-cutaway side views of the folding knife  100 , illustrating certain components of the knife in the closed position, in a first exemplary position in the opening sequence, a second exemplary position in the opening sequence, a third exemplary position in the opening sequence, a fourth exemplary position in the opening sequence, and the opened position. 
   It should be understood that while the folding knife illustrated in  FIGS. 6A-7F  is primarily shown and described as including the features of the folding knife  100 , the folding knife illustrated in  FIGS. 6A-7F  may incorporate any of the features or elements of the folding knife  100  or the folding knife  200 . 
   As illustrated in  FIGS. 6A-7F , the folding knife  100  is assembled as described above. In the closed position, as illustrated in  FIGS. 6A and 7A , the guard  120  and blade  110  are nested within the handle  130 . When in the closed position, the tang pin  118  is essentially trapped between the blade tang pin aperture  116 , terminal ends of the arcuate guard slots  124  and  124 ′, and terminal ends of the arcuate handle slots  134  and  134 . Thus, so long as the folding knife  100 , and more particularly the guard  120  is maintained in the closed position, by either the user maintaining an encircling grip on the folding knife  100  or maintaining the lock means  170  (if included) in a locked position, the blade  110  is secured within the guard  120  and the handle  130 . 
   To open the folding knife  100 , as illustrated in FIGS.  6 B and  7 B- 7 C, the lock means (if included) is unlocked, and the guard  120  and blade  110  are rotated together, via the pivot pin  150 , out of the handle  130 . In various exemplary embodiments, the weight of the blade  110  is greater than the weight of the guard  120 . Thus, opening of the folding knife  100  may be initiated by rotating the folding knife  100  in the direction of the pivot end and then stopping the rotation of the folding knife (i.e., by a flick of the wrist). Because of the weight of the knife blade  110 , when the rotation of the folding knife  100  is stopped, the momentum of the blade  110  continues to pivot the blade  110 , about the pivot pin  150 , towards the open position. 
   As the blade  110  pivots towards the open position, the tang pin  118  travels within the arcuate handle slots  134  and  134 ′, while continuing to engage a terminal end of the arcuate guard slots  124  and  124 ′. So long as the tang pin  118  engages a terminal end of the arcuate guard slots  124  and  124 ′, the guard  120  rotates with the blade  110 . Thus, the blade  110  and the guard  120  generally rotate together, as the tang pin  118  travels along the arcuate handle slots  134  and  134 ′, until the tang pin  118  is rotated into contact with a terminal end of the arcuate handle slots  134  and  134 ′. 
   As illustrated in FIGS.  6 B and  7 D- 7 E, after the blade  100  rotates approximately 180°, the tang pin  118  is rotated into contact with a terminal end of the arcuate handle slots  134  and  134 ′, rotation of the blade  110 , about the pivot pin  150 , is stopped. When rotation of the blade  110  is stopped, rotation of the guard  120  continues as the stationary tang pin  118  continues to interact with the arcuate guard slots  124  and  124 ′. 
   As illustrated in  FIGS. 6C and 7F , rotation of the guard  120  continues until a terminal end of the arcuate guard slots  124  and  124 ′ is rotated into contact with the stationary tang pin  118 . When the terminal end of the arcuate guard slots  124  and  124 ′ is rotated into contact with the stationary tang pin  118 , rotation of the guard  120  is stopped and the folding knife  100  is in the opened position. When the folding knife  100  is in the opened position, the guard  120  is nested substantially inside the handle  130  and the tang pin  118  is essentially trapped between the blade tang pin aperture  116 , terminal ends of the arcuate guard slots  124  and  124 ′, and terminal ends of the arcuate handle slots  134  and  134 ′. 
   So long as the folding knife  100 , and more particularly the guard  120 , is maintained in the opened position, by either the user maintaining a grip on the handle  130  or maintaining the lock means  170  (if included) in a locked position, the blade  110  is secured in the opened position. Thus, when the folding knife  100  is in the opened position and is grasped in a normal, working manner, the blade  110  cannot be closed on the user&#39;s fingers. 
   It should be understood that reversing this process closes both the guard  120  and the blade  110  safely within the handle  130 . 
   While this invention has been described in conjunction with the exemplary embodiments outlined above, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. 
   For example, while the folding knife has been shown as having a particular overall appearance, it should be appreciated that the elements of the folding knife may be employed in a folding knife having a different overall appearance. Furthermore, it should also be appreciated that the knife blade  110  or  210  may be replaced by another instrument, implement, or tool, such as, for example, screwdriver, a pen, pencil, or other marking device, one or more keys, a saw blade, or any other instrument, implement, or tool. In these embodiments, the overall shape and size of the guard  120  or  220  and the handle  130  or  230  may be altered to accommodate the instrument, implement, or tool, while still employing the design factors and operating principles of this invention. 
   Such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed exemplary embodiments. It is to be understood that the phraseology of terminology employed herein is for the purpose of description and not of limitation. Accordingly, the foregoing description of the exemplary embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes, modifications, and/or adaptations may be made without departing from the spirit and scope of this invention.