Abstract:
An improvement of a folding knife locking mechanism with an adjustable wedge to remove blade slop. The present mechanism allows for smooth opening and closing of the blade by limiting friction against the blade as it rotates. This knife has a bearing system for low friction blade rotation. Also the leaf strap lock is arranged so that it only comes into contact with the blade at the start of opening and at the end of opening, further limiting the friction forces against the blade. Provided is also an adjustment wedge to remove blade lock slop. In the manufacturing process loose tolerances can be adjusted out using the adjustment wedge. Normal use wear against the stop pins and handles can cause some looseness of the blade which can also be removed by the adjustment wedge.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application No. 61/575,802 , filed on Aug. 29, 2011, and U.S. Provisional Application No. 61/585,928, filed on Jan. 12, 2012, the full disclosures of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to folding knives, and particularly to a method of profiling the level of force deployed in opening of a flip open blade as well as an adjustable lock to compensate for wear. 
     BACKGROUND 
     Folding knives with a lock mechanism to keep the blade open are well known. Typically these knives have a spring actuated lock that rests either on the side of the blade or on the blade tang as the blade rotates. This positioning of the lock, and its constant contact with the blade or tang during rotation, causes friction so that blade rotation is constantly subject to drag. Also, when the blade has been in use, the strap lock interface and locking surfaces wear and the blade develops some slop or lock wiggle. This makes for a low quality knife and unsafe conditions. 
     A very popular design for modern folding knives is a configuration that allows for the blade to be opened by exerting pressure on a spur of the tang, protruding above the handle frame. This spur is often called a “flipper”. These knives are commonly called “Flipper Knives” and most variations rely on a locking mechanism based on the liner lock. Liner locks are well known, and an example can be found in U.S. Pat. No. 825,093 to Watson. The disadvantage of using a liner lock, in conjunction with this opening method, is that the liner lock is in continuous contact with the blade tang when the knife rotates, which generates an unacceptable level of drag on the opening blade. Folding knives of this design are difficult to open and prone to misfire, requiring an enhanced level of dexterity by the operator. 
     Automatic opening knives are well known in the prior art, encompassing a wide variety of features. The so-called double action configuration allows the user the option of either opening the blade in the usual automatic mode, of depressing the firing pin, or conversely, simply opening the blade with the thumb or other hand. 
     Most automatic opening knives are provided with a separate safety switch intended to prevent accidental firing and a very few combine the safety and the firing pin within the same button, which may be shifted in an alternate plane of motion, to engage or disengage the safety feature before firing. 
     The basic configuration of the blade lock, as disclosed herein, has much in common with automatic knives developed in Italy during the nineteenth century. The Italian design, herein referred to as a strap lock, relies on a flat spring affixed to the spine of the handle frame near the butt of the handle and resiliently capturing a protrusion on the blade tang to cause lock up when opened. The disadvantage of the Italian design is lack of a means to compensate for strap lock wear and it&#39;s incompatibility with modern flipper opening methods, due to the fact that the flipper spur must pass through the area occupied by the strap lock. 
     Prior art patents are as follows: US 462,141, U.S. Pat. No. 1,263,440, and U.S. Pat. No. 5,095,624. 
     BRIEF SUMMARY 
     The following presents a simplified summary of some embodiments of the invention in order to provide a basic understanding of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some embodiments of the invention in a simplified form as a prelude to the more detailed description that is presented later. 
     Embodiments herein are directed to providing a knife with a locking mechanism with an adjustable wedge to remove blade slop. In the manufacturing process loose tolerances can be adjusted out using the adjustment wedge, thereby avoiding the necessity for precision parts. Normal use of the knife can cause some wear between the stop pin and handles, as well as the lock interface, leading to some looseness of the connection of the blade and lock. This looseness, or slop, can also be removed by the adjustment wedge. 
     In accordance with additional embodiments, the present mechanism allows for smooth opening and closing of the blade by limiting friction against the blade as it rotates. Typically, locking folding knives have some frictional forces against the blade, be it a ball detent or washers. In contrast, embodiments herein provide a bearing system for low friction blade rotation. 
     Also, in accordance with further embodiments, a strap lock for the blade is arranged so that the strap lock comes into contact with the blade only at the start of opening and at the end of opening. This feature further limits friction forces against the blade. Thus, unlike many prior art knives, the locking mechanism of the knife does not contact the blade during the majority of the blade&#39;s rotation from closed to opened 
     In accordance with aspects herein, a closely controlled level of resistance is provided at the beginning of the opening cycle, so that when sufficient force is supplied by a user to overcome this resistance and the resistance is overcome, the force the user is supplying to the blade is sufficient to propel the blade fully to open and lock without fail. 
     Features herein also provide for an automatic opening knife that includes the double action option of opening, either manually by thumb pressure against a blade mounted stud or hole, or automatically by manipulating a firing switch. Embodiments utilize one or more of a safety that is integral to the firing switch, a lock that is adjustable to compensate for lock wear, a main spring that is adjustable for power output, as well as the added feature of both ambidextrous opening and ambidextrous delocking, although other features may be used. 
     For a fuller understanding of the nature and advantages of the present invention, reference should be made to the ensuing detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a front perspective view of a folding knife in accordance with embodiments, with the blade of the folding knife open. 
         FIG. 1B  is a front perspective view of the folding knife of  FIG. 1 , with the blade closed. 
         FIG. 2  is an exploded view of the knife of  FIG. 1 . 
         FIG. 3A  is a left plan view of a knife blade for the knife of  FIG. 1 . 
         FIG. 3B  is a detail view  3 B of  FIG. 3A , showing a blade lock notch for the knife of  FIG. 1 . 
         FIG. 3C  is a detail view  3 C of  FIG. 3A , showing a blade closed detent notch for the knife of  FIG. 1 . 
         FIG. 4A  is a left plan view of a left handle for the knife of  FIG. 1 . 
         FIG. 4B  is a right plan view of the left handle. 
         FIG. 5  is a front perspective view of the left handle inlay for the knife of  FIG. 1 . 
         FIG. 6A  is a top view of a strap lock for the knife of  FIG. 1 . 
         FIG. 6B  is a left view of the strap lock. 
         FIG. 6C  is a front perspective view of the strap lock. 
         FIG. 7A  is a left plan view of a spacer for the knife of  FIG. 1 . 
         FIG. 7B  is a front perspective view of the spacer. 
         FIG. 8A  is a left plan view of an adjustment wedge for the knife of  FIG. 1 . 
         FIG. 8B  is a front perspective of the adjustment wedge. 
         FIG. 9A  is a front perspective view of a bearing race for the knife of  FIG. 1 . 
         FIG. 9B  is a front perspective view of a stop pin for the knife of  FIG. 1 . 
         FIG. 9C  is a front perspective view of a pivot pin for the knife of  FIG. 1 . 
         FIG. 9D  is a front perspective view of a bearing washer for the knife of  FIG. 1 . 
         FIGS. 10A-10O  are a sequence view and detail views showing the blade detent and blade lock engagement of the strap lock moving from the closed to open locking position. 
         FIGS. 11A-11C  are views and detail views showing the adjustment wedge fully adjusted to minimize blade slop at the blade notch end. 
         FIGS. 11D-11F  are views and detail views showing the adjustment wedge minimally adjusted allowing more blade slop at the blade notch end. 
         FIG. 12  shows an additional embodiment of a folding knife including an automatic opener, and shown in a fully assembled, closed position 
         FIG. 13  shows same view as  FIG. 12  with handle overlay removed. 
         FIG. 14  shows same view as  FIG. 12  but with top half of handle frame removed. 
         FIGS. 15A-C  show a thrust arm assembly for the automatic opener of the knife of  FIG. 12 , with the three figures showing three different views. 
         FIGS. 16A-C  show two different views of a rocking sear for the automatic opener of the knife of  FIG. 12 . 
         FIGS. 17A and 17B  show two views of a trigger slide for the knife of  FIG. 12 . 
         FIG. 18  shows a trigger slide for the knife of  FIG. 12 , with the trigger slide in a safe position. 
         FIG. 19  shows the trigger slide in shows the trigger slide of  FIG. 18  with a trigger switch displaced in preparation for firing. 
         FIG. 20  shows the trigger slide at the end of a firing cycle. 
         FIG. 21  shows the thrust arm and rocking sear of  FIGS. 15 and 16  prior to firing. 
         FIG. 22  shows the thrust arm and rocking sear of  FIG. 21  after firing. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, various embodiments of the present invention will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the present invention may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiment being described. 
       FIG. 1A-1B  shows a folding knife  8  in accordance with embodiments. The knife  8  has left and right handles  20   a  and  20   b  which provide safe storage for the blade  10  when closed ( FIG. 1B ). Although the two side pieces of the knife structure are referred to herein as “handles”  20   a  and  20   b , as used herein, “handle” is any structure of the knife that is designed to be held by a user, and may or may not include a handle frame or other pieces of the knife body, but typically not the blade  10 . The blade  10  rotates around a pivot pin  70  ( FIG. 2 ) from the storage area between the handles  20   a  and  20   b  ( FIG. 1B ) to an open, ready-for-use position ( FIG. 1A ). 
     As shown in  FIG. 3A , the blade  10  includes a tang  9  at a proximal end. The tang  9  of the blade  10  has a hole  12  for the pivot pin  70 . 
     A radial arc is formed about the proximal end of the tang  9 . This arc includes a stop  13  at a lower, blade side of the tang, and a stop  14  at the opposite end of the arc, or at a top of the blade. The stop  13  engages a pin  80  ( FIG. 10C ) and provides a rest when the blade  10  is in the closed position and prevents over-rotation of the blade. The stop  14  engages the pin  80  ( FIG. 10O ) for preventing over-rotation when the blade  10  is in the open position. 
     As best shown in  FIGS. 3A-3C , the bottom edge of the tang  9  includes a flipper  11  and a detent extension  16 . The detent extension  16  includes a cam surface, or ramp  18  along a proximal edge. A tab notch, or tab  15  is located just below the flipper  11 , and between the flipper  11  and the detent extension  16 . As described in more detail below, the flipper  11  is a protrusion of the tang  9  used for opening the blade. A ramp  17  is located on the opposite side of the tang  9  from the flipper  11 . A lock notch  19  is located just below the ramp  17 . 
       FIG. 3B  shows a detail view of the lock notch  19  which fully engages the slot  42  in the strap lock  40  when the blade is in the open position ( FIGS. 10M and 10N ). The lock notch  19  is part of the lock notch and ramp  17 .  FIG. 3C  is a detail view of the closed position detent extension  16  and a ramp  18 , which engage the slot  42  in the strap lock  40  when the blade is closed (e.g.,  FIG. 10C ), as described below. 
     The strap lock  40  is provided on the back of the knife  8 . The proximal end (right in  FIG. 6A ) of the strap lock  40  is fixed to the top of the knife by an adjustment wedge  60  and a spacer element  50 , both of which are described in more detail below. 
     The strap lock  40  is flexible, yet resilient, so that a distal end (left in  FIG. 6A ) can bend away from the top edge of the knife  8 . To this end, the strap lock  40  is formed of a flexible, yet resilient material that biases towards a straight configuration (towards the handle), yet is flexible enough to move away from the handle upon the application of sufficient force, for example by a user pulling upward. To aid in bending of the strap lock  40 , a relief  44  can be provided to allow more flexible bending of the strap lock  40  in the region of the relief. 
     To aid in moving the distal end of the strap lock  40  upward, a thumb ridge  43  can be provided for a user to engage with a thumb to move the strap lock  40  upward. In addition, the strap lock  40  can be wider than the handle, with overlapping outer edges of the strap lock providing a gripping surface for a user to grasp the strap lock and pull upward. 
     The strap lock  40  includes a slot  42  ( FIG. 6A ) for the blade flipper  11  to pass thru (see  FIG. 1B ).  FIG. 6B  shows the side view of the arm and  FIG. 6C  shows a perspective view. The slot  42  includes a lock engagement surface  41  ( FIG. 6A ) at a distal, inner edge. The strap lock  40  includes a second slot  46  to receive the spacer  50 . A proximal side of the slot  46  includes a strap lock interface  45  along an inner, proximal edge. As described below, the strap lock interface  45  is engaged by a slanted proximal edge of the wedge  60  as the wedge is tightened down to adjust position of the strap lock  40 . Holes  47  are positioned on opposite sides of the slot  46  to receive fasteners  141  ( FIG. 2 ) that fasten the strap lock  40  to the spacer  50 . 
       FIG. 2  shows an exploded view of the knife  8 . The blade  10  is fastened to the handles  20   a  and  20   b  between washers  100   a  and  100   b  and bearings  110   a  and  110   b  by the pivot pin  70 . The washers  100   a  and  100   b  and bearings  110   a  and  110   b  provide smooth travel of the blade  10  between closed and opened positions. The pivot pin  70  also fastens the handles  20   a  and  20   b  and is secured by screws  160   a  and  160   b.    
       FIG. 4A  shows the left handle  20   a . A hole  21   a  is provided to secure the pivot pin  70 . Holes  23   a  are provided to secure a spacer  50  ( FIG. 2 ). A pocket  22   a  is provided for the inlay  30   a .  FIG. 4B  shows back face of the left handle  20   a . A hole  24   a  ( FIG. 4B ) is provided for the spacer pin  170 , and a hole  25   a  is provided for the stop pin  80 . A recess  26   a  is provided for the bearings  110 . The right handle  20   b  is a mirror of the left handle  20   a.    
       FIG. 7A  shows a side view of the spacer  50 , and  FIG. 7B  shows a perspective view. The spacer  50  fits between the proximal ends of the handles  20   a  and  20   b , and properly spaces the handle so that the blade  10  may fit between the handles. The spacer  50  includes a hole  56  for the spacer pin  170 , holes  54  for the fastening screws  130   a  and  130   b , holes  52  to fasten to the strap lock  40 , and an adjustment wedge interface  51  to receive the adjustment wedge  60 . A hole  53  is provided to secure the adjustment wedge  60 . Holes  55  are provided to secure a belt clip  90 . 
     The handles  20   a  and  20   b  are fastened to the spacer  50  by screws  130   a  and  130   b . The strap lock  40  is fastened to the spacer  50  by the screws  141 . The stop pin  80  is held between the handles  20   a  and  20   b . A belt clip  90  is provided and secured by screws  150  to the spacer  50 . The adjustment wedge  60  is fastened to the spacer  50  by a screw  140 . Decorative handle inlays  30   a  and  30   b  are provided here also. 
       FIG. 8A  shows a side view of the adjustment wedge  60 .  FIG. 8B  shows a perspective view. The adjustment wedge includes a upright surface  62  on a distal side, and an angle surface  61  on the opposite, proximal side. A hole  63  extends through the adjustment wedge  60  to receive a screw  140  to secure the adjustment wedge to the spacer  50 . 
       FIG. 9A  is a perspective view of the bearings  110 . 
       FIG. 9B  shows a perspective of the stop pin  80 . 
       FIG. 9C  shows a perspective of the pivot pin  70 . 
       FIG. 9D  shows a perspective of the bearing washer  100 . 
       FIG. 5  shows the handle inlay  30   a  and pocket  31   a  for a logo. 
     Description of the Opening Operation of the Knife: 
       FIGS. 1B and 10A  show the knife  9  in the stored position. The blade  10  is in the closed position between the handles  20   a  and  20   b .  FIG. 10B  is a section view of the blade in the closed position.  FIG. 10C  shows a detail view of the connection of the blade  10  to the strap lock  40 . The strap lock  40  is biased down toward the pivot  70  by the resilience and bias of the material used for the strap lock  40 . The detent extension  16 , via the cam notch  15 , is in contact with a bottom of the strap lock  40 , and is pressed downward by the strap lock  40 . 
     In this closed position, the tab notch  15  fits around the lock engagement surface  41  of the slot  42  on the strap lock  40 . The bias and resilience of the spring arm  40  pushes down on the lower, inside edge of the tab notch  15 , causing the blade  10  to be pushed more toward the closed position, preventing accidental or unintentional opening of the blade  10 . The blade  10  is stopped from rotating further into the handle by the stop  13  engaging the stop pin  80 . 
     When a user wishes to open the blade  10  to the ready for use position, the user pulls back on the outer, exposed protrusion of the flipper  11  (the exposed portion of the flipper in  FIG. 10C ) with the index finger while gripping the handles  20   a  and  20   b  with the thumb (one handle  20   b ) and the other three fingers of the hand (other handle  20   a ). 
       FIG. 10D  shows the section view of the blade  10  as the user starts to pulls back on the flipper  11  with the index finger, starting the opening of the blade  10 .  FIG. 10E  shows a detail view of engagement of the tab notch  15  with the strap lock  40 . As the flipper  11  is pulled back by the user, the detent extension  16  rotates up against the strap lock  40 , bending the strap lock upwards. The strap lock  40  flexes upward while the leaf spring action of the material in the strap lock pushes back. The relief area aids in flexibility and the leaf spring effect of the strap lock. This resistance to bending is overcome by the application of sufficient pulling force on the flipper  11  by the user. 
       FIG. 10F  is a section view of the blade  10  opening further.  FIG. 10G  shows a detail view of the strap lock  40  in contact with the detent extension  16 . As shown in  FIG. 10G , as the blade is further rotated open, the ramp  18  of the detent  16  pushes against the strap lock  40  on the strap lock interface  41 , pushing up on the strap lock  40 , eventually with the ramp  18  sliding over the lock engagement surface  41  and passing thru the slot  42 , allowing free rotation of the blade  10  as the ramp no longer engages the strap lock  40 . 
     The amount of pressure applied by a user to rotate the ramp  18  over the lock engagement surface  41  builds until sufficient to overcome the resiliency and spring tension of the strap lock  40 . This pressure/force, when the engagement releases, creates rotational inertia for the blade  10  when the engagement surface eventually rolls over the lock engagement surface  41 . This inertia causes the blade  10  to rotate fully to the open position and snap into locked engagement. 
       FIG. 10H  shows a section view of the blade  10  almost fully open.  FIG. 10I  shows a detail view of the engagement of the blade  10  and the strap lock  40 . The lock ramp  17  is in contact with the strap lock  40 . 
       FIG. 10J  shows a section view of the blade  10  opening further.  FIG. 10K  shows a detail view. As the blade  10  rotates more, the ramp  17  eventually engages and pushes up on the strap lock  40 . Due to the inertia of the blade (discussed earlier), this action typically occurs through momentum of the blade rotation upon release from the lock engagement surface  41 . Thus, the momentum of the blade is sufficient not only to rotate the blade fully open, but to provide enough force to move the strap lock  40  upward via engagement by the ramp  17 . If the momentum is not sufficient, a user may grip and further rotate the blade  10  to the fully opened position. A user can, with proper quick and steady application of pressure to the flipper  11 , build sufficient pressure through the flipper to rotate the blade over the ramp  18 , providing sufficient pressure and ultimately blade inertia to cause the blade to rotate freely about the pivot  70  and momentum sufficient to cause the ramp  17  to engage and push out and lock into the distal end of the strap lock  40 . The pressure/force buildup caused by the resistant of the ramp  18  to sliding over the lock engagement surface  41  at the beginning of the opening process causes this action to naturally occur. So unlike prior art flipper knives, this action occurs almost automatically, instead of requiring a lot of practice by a user. 
       FIG. 10L  shows a section view of the blade fully open.  FIG. 10M  shows a detail view of the blade  10  in contact with the strap lock  40 . When fully opened, the blade is locked in the open position by the slot  42  in the strap lock  40  fitting around the blade lock notch  19  on the proximal end of the rear of the blade  10 . The blade  10  is stopped from further opening by the stop  14  engaging the stop pin  80 . The blade lock notch  19  is in contact with strap lock interface  41 . The ramp  17  is passed in to the slot  42 . The knife is ready for use. 
       FIG. 10N  shows a section view of the blade  10  fully open.  FIG. 10O  shows a detail view of engagement of the blade  10  with the strap lock  40 . The strap lock  40  is biased down toward the pivot  70 . As described above, the blade  10  rotates, either freely or by a user pulling the blade, until the ramp  17  engages the strap lock  40 , in sequence first pressing it upward and passing into the slot  42 , permitting the strap lock  40  to freely move back downward. At the end of this movement, the strap lock interface  41  pushes down on and fits behind the blade lock notch  19 . The downward force of the strap lock  40  causes the blade  10  to rotate further open and locks the stop  14  against the stop pin  80 . This prevents the blade  10  from closing and makes a tight lockup without blade slop. 
     The knife is returned to the storage position is as follows: The user pushes upward on the strap lock  40  unlocking the ramp  17  on the blade  10  from the slot  42  in the strap lock  40 . The user may pull back on the strap lock  40 , for example by gripping either side of the strap lock at opposite sides of the thumb ridge  43 , or by pushing up on the thumb ridge  43  with a thumb. The user then pushes down on the top of the blade  10 , rotating the blade  10  back to the stored position. The flipper  11  fits into the slot  42  in the strap lock  40  and the engagement of the lock engagement surface  41  with the inside of the latch  15  holds the blade closed against the strap lock  40 . The knife is stored. 
     A precise fit of the blade lock notch  19  with the strap lock interface  41  prevents slop in the blade when locked in the open position. Over multiple openings and closings of the blade  10 , the blade lock notch  19  and/or the strap lock interface  41  may slightly wear, permitting some slop in the locked-open blade. To prevent such slop, the adjustment wedge  60  permits movement, tightening, and locking of the strap lock  40  to a position where the blade lock notch  19  precisely fits against the strap lock interface  41 .  FIG. 11A  shows a section view of the assembly with the adjustment wedge  60  fully engaged when the adjustment screw  140  is rotated clockwise.  FIG. 11C  shows a detail view. The adjustment wedge  60  is in place so that surface  62  is in contact with spacer stop surface  51  and the angled wedge edge  61  has maximum contact with strap lock interface  45  ( FIG. 11F ). 
     Tightening the screw  140  causes the angled wedge edge  61  to cam against the strap lock interface  45 , forcing the strap lock  40  back away from the pivot toward the tang end of the handle. Leaf spring screws  141  are loosened and tightened to allow the strap lock  40  to slide and then be secured to the spacer  50 . These screws  141  are loosened with the blade in the locked, opened position, and then the screw  140  is tightened until the strap lock  40  cannot move back further. The screws  141  are then tightened to prevent further movement of the strap lock  40 . With the adjustment wedge  60  fully tightened by the screw  140 , the maximum amount of blade slop can be removed.  FIG. 11B  shows the blade lock notch end  19  in full contact with the strap lock interface  41 . This forces the blade stop  14  further open against the stop pin  80 , removing blade slop. 
       FIG. 11D  shows a section view of the assembly with the adjustment wedge  60  fully disengaged when the adjustment screw  140  is rotated counterclockwise.  FIG. 11F  shows a detail view. The adjustment wedge  60  is up so that surface  62  is in contact with spacer stop surface  51  and the angled wedge edge  61  has minimal contact with the adjustment wedge interface  45 . This forces the strap lock  40  fully forward toward the pivot. Leaf spring screws  141  are loosened and tightened to allow the strap lock  40  to slide and secure it to the spacer  50 . With the adjustment wedge  60  in this position fully disengaged the blade has maximum slop. 
       FIG. 11E  shows the blade lock notch end  19  not in contact with the strap lock interface  41 . This allows blade slop between the blade stop  14  against the stop pin  80  and blade lock notch end  19  spaced away from strap lock interface  41 . 
       FIG. 12  shows an additional embodiment including some of the previously described features, and additionally including an automatic opener. Briefly described, the knife of  FIG. 12  includes a trigger button  254  that can be manipulated by a user to automatically open the knife. The trigger button is designed for two motions, one of which unlocks the automatic opener and another of which actuates the automatic opener. When trigger button  254  is lifted by thumb pressure in direction of arrow c,  FIG. 22 , the thumb may then pull trigger button  254  rearward in the direction of arrow d. This motion causes the automatic opener to fire, which rotates the blade  210  to overcome the resistance of the strap lock  40  (described above). 
     Details of the trigger mechanism can be seen in  FIGS. 13 , and  17 - 20 . The trigger mechanism includes the trigger button  254 , which is mounted on the end of a flexible trigger stem  264  ( FIG. 20 ). The trigger stem  264  is mounted on a trigger slide  256  and includes a, in the form of a protrusion on a bottom side. As can be seen in  FIGS. 19 and 13 , the trigger slide safety catch  258  is normally is positioned behind a trigger slide safety boss  260 . The trigger slide safety boss  260  is fixed to the handles of the knife, and does not move relative to the knife. The trigger slide  256  is mounted for sliding movement relative to the trigger slide safety boss  260  and the knife. 
     In the normal position, shown in  FIG. 18 , the trigger slide safety boss  260  is positioned behind the trigger slide safety catch  258 , and prevents movement of the trigger slide  256  rearward. As can be seen in  FIG. 19 , movement upward of the trigger button  254  (the flexibility of the flexible trigger stem  264  permits this movement) moves the trigger slide safety catch  258  upward so that it may move over the trigger slide safety boss  260 . In this position, the user may slide the trigger button  254  rearward (right in  FIG. 19 ) so that the trigger slide  256  moves rearward as well. 
     Details of the automatic opener are shown in  FIGS. 14-16 , and  21 - 22 . The automatic opener includes a rocking sear  242  mounted on a fixed rocking sear pivot point  244 . The fixed rocking sear pivot point  244  is attached to the knife so that the rocking sear can pivot about it, and in the embodiment shown in the drawings, includes two attachments, extending outward, so that a thrust arm  266 , described below, can move freely between the two attachments. As can be seen in  FIG. 16 , the rocking sear is stamped to a U-shape (also so the thrust arm  266  can move through it), and includes a rocking sear roller  246  at an upper, rear portion, and a pair of rocking sear control studs  248  at a lower, front edge. 
     The thrust arm  266  is rigidly connected to a thrust arm pivot plate  268 . As shown in  FIG. 15 , the thrust arm  266  can be a laminated three-layer structure, and the pivot plate  268  can be two plates attached on the outside of the thrust arm  266 . Rivets  276  may be used to connect the layers together. A protrusion  271  is attached to the top of the pivot plate  268 , and a notch  272  is formed in front the protrusion. The pivot plate  268  is shaped as a triangle, and is mounted for pivoting movement about a thrust arm assembly pivot point  278 . The protrusion  271  and the thrust arm  266  are mounted on the other points of the triangle. 
     A thrust arm roller  270  is positioned on a leading end of the thrust arm  266 . As can be seen in  FIG. 14 , the thrust arm roller  270  seats against a back edge of the knife tang. A main spring  284  ( FIG. 21 ) is mounted behind the pivot plate  268 . The main spring  284  is mounted on a main spring plunger  286  ( FIG. 14 ) and biases the thrust arm roller  270  into rotation about the thrust arm assembly pivot point  278 . 
     As can be seen in  FIGS. 21 and 22 , the rocking sear  242  mounts around the thrust arm  266 , so that the top arm of the rocking sear is parallel to the thrust arm in a normal position. The rocking sear roller  246  fits into the notch  272 , and prevents rotation of the thrust arm  266  against the bias of the main spring  284 . 
     A rocking sear rebound spring  252  includes a rocking sear follower  250  mounted at an end. The rebound spring  252  biases the follower  250  into contact with the rocking sear control stud  248 , biasing the rocking sear roller  246  into engagement with the notch  272 . In this manner, under normal conditions, the rebound spring  252  prevents accidental engagement of the thrust arm  266 . 
     As can be seen in  FIGS. 18-20 , the rear edge of the trigger slide  256  engages an opposite side of the rocking sear control stud  248 . 
     When the trigger mechanism is in the normal position, the trigger button  254  is held in position by virtue of the resilient force applied by the flexible trigger stem  264  of trigger slide  256  being held in engagement with trigger slide safety boss  260  ( FIG. 18 ). The rocking sear  242  is positioned behind the trigger slide  256  (also  FIG. 18 ), as described above. The rocking sear roller  246  is lodged in the notch ( FIG. 21 ), preventing actuation of the thrust arm  266 . 
     To actuate the automatic opener, the trigger mechanism is first unlocked (taken out of safety) and then is actuated. To unlock the trigger mechanism, the trigger button  254  is lifted by thumb pressure in direction of arrow c,  FIG. 12 . At this point, the trigger slide safety catch  258  is moved from behind the trigger slide safety boss  260  ( FIG. 19 ), permitting movement of the trigger slide  256  rearward. The thumb may then pull the trigger button  254  rearward in the direction of arrow d ( FIG. 12 ). As the trigger slide  256  travels in the direction of arrow d, its engagement with rocking sear control stud  248 , produces a counter clockwise rotation of the rocking sear  242 , about rocking sear pivot point  244 , overcoming the resilient loading of rocking sear rebound spring  252 . 
     As the rocking sear  242  rotates, the rocking sear roller  246  disengages the notch  272  in the thrust arm  266 , releasing the protrusion  271  and allowing the thrust arm  266  to rotate in a counterclockwise direction, in response to the release of energy stored in mainspring  284 . As the thrust arm  266  rotates, the thrust arm roller  270  bears against the tang of the blade  210 , which propels blade  210  to rotate about pivot point  216 , to assume the open position as previously described. To perform a full automatic opening until the blade is locked, the mainspring  284  is of a spring tension that is sufficient to move the blade  210  past the strap lock. As described previously, such force is sufficient to freely rotate the blade to a fully opened, locked position. 
     Closing the blade  210  is as previously described. First the blade  210  is unlocked from the strap lock, and then the blade is rotated to a closed position. As the blade  210  is folded into handle frames  212 , the tang of the blade  210  contacts the roller  270  of the thrust arm  266 , returning thrust arm  266  to its cocked position against the pressure of main spring  284 , allowing rocking sear  242  to reengage thrust arm sear notch  272  which is the beginning of the cycle prior to the next firing 
     As can be readily understood by a careful analysis of the foregoing, embodiments herein offer multiple substantial improvements over the prior art. The configuration of the strap lock allows for a predetermined level of force to be restrained prior to firing which insures a successful opening cycle to lock. The strap lock being subject to the gripping force of the operator&#39;s hand, when used in the open blade position, contributes to the security of a locked open blade. The symmetrical configuration of the strap lock provides for completely ambidextrous delocking. The main spring  284  of the automatic opener can be adjustable for various power levels and the blade may be opened either manually or automatically by a trigger button with integral safety. 
     Other variations are within the spirit of the present invention. Thus, while the invention is susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention, as defined in the appended claims. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. 
     All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.