Abstract:
A method and apparatus for a knife having a handle, a blade and a locking mechanism whereby the mechanism provides a pivot point between the handle and blade holder and at least two selective locking positions between the blade and the handle. In one embodiment the knife is a utility knife including a blade holder that houses the blade and pivots with the blade relative to the handle.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    Embodiments of the present invention generally relate to a locking mechanism for a knife. More particularly, the invention relates to a locking mechanism for a utility knife wherein a blade and blade holder of the knife may be rotationally locked in any one of several predetermined positions relative to the handle. 
         [0003]    2. Description of the Related Art 
         [0004]    A conventional folding knife includes a blade and a handle. In the case of a utility knife, the blade is retained in a blade holder that rotates around a pivot point relative to the handle. The blade holder in the conventional folding utility knife typically includes two positions, an opened position and a closed position. In the closed position, a portion of the blade holder is positioned in the handle such that a cutting edge of the blade in the blade is protected. 
         [0005]    The conventional folding utility knife may include a lock mechanism to lock the blade holder in a position relative to the handle, typically the opened position to prevent accidently movement of the blade during use. Even though the conventional folding utility knife may be locked in the opened position, there is a need for an inter-lock mechanism for use with the folding utility knife that is capable of locking the blade holder in an opened position, a closed position and any number of intermediate positions in order to take full advantage of the various uses of a knife, especially a utility knife. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention generally relates to a knife having a handle, a blade and a locking mechanism, providing a pivot point between the handle and blade holder as well as at least two selective locking positions between the blade and the handle. In one embodiment the knife is a utility knife including a blade holder that houses the blade and pivots with the blade relative to the handle. 
         [0007]    In another embodiment, the locking mechanism includes a lock button a lock button that extends through the handle and blade holder to form a pivot point between the handle and blade holder and the lock button provides at least two selective locking positions between the blade holder and the handle. 
         [0008]    In yet another embodiment, a method is provided that includes depressing a spring-biased lock button on a first side of the knife, thereby causing a blade locking formation to be displaced from engagement with a first blade locking groove in a blade holder, and rotating the blade holder from a first rotational position relative to a handle, to a second rotational position relative to the handle whereby, in the second rotational position, the blade locking formation becomes engaged with a second blade locking groove. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
           [0010]      FIG. 1  is a perspective view of a utility knife having embodiments of the present invention. 
           [0011]      FIG. 2  is an exploded view of the knife of  FIG. 1 . 
           [0012]      FIG. 3  is an enlarged view of a second portion of a lock button. 
           [0013]      FIG. 4  illustrates the connection between a first and second portions of the lock button. 
           [0014]      FIG. 5  is a view illustrating one handle portion of the knife having an aperture formed therein with radially extending groves extending from the aperture. 
           [0015]      FIG. 6  illustrates a blade and blade holder with an aperture formed in the blade holder with blade locking grooves extending radially outward therefrom. 
           [0016]      FIG. 7  is a section view showing the lock button, handle and blade holder with the blade holder locked in a predetermined rotational position relative to the handle. 
           [0017]      FIG. 8  is a section view showing the lock button, handle and blade holder with the blade holder free to rotate about a pivot point formed about the lock button. 
           [0018]      FIGS. 9 and 10  are side views of one handle portion showing a blade locking formation in a locked ( FIG. 9 ) and unlocked position relative to the blade holder (not shown). 
           [0019]      FIGS. 11-14  are partial section views showing the knife in various locked positions and illustrating the location of the blade locking formation disposed in various blade locking grooves of the blade holder. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The present invention relates to a locking mechanism for a knife, wherein the blade and/or blade holder can be rotationally fixed at several locations relative to the knife handle.  FIG. 1  is a perspective view illustrating a knife  100  having a locking mechanism according to one aspect of the invention. The knife of  FIG. 1  is a utility knife wherein a blade  110  is disposed in a blade holder  150  and the assembly, including the blade holder moves between an open and closed position about a pivot point located in the handle of the knife. The knife  100  comprises a handle having a first  200   a  and second  200   b  portion, a blade holder  150  and a lock button  300  extending through the handle portions as well as the blade holder. Included in the embodiment is a rotating member  375  used to facilitate the removal and installation of a blade  110  into and out of the blade holder  150 . 
         [0021]      FIG. 2  is an exploded view of the knife  100  of  FIG. 1  illustrating the relationship between the handle portions  200   a ,  200   b , the blade and blade holder  150  and the lock button  300 . In the embodiment shown, a central handle portion  205  fits between the outer handle portions  200   a, b  but does not form a part of the locking mechanism. The lock button  300  is a two-piece  300   a ,  300   b  assembly which extends through the blade holder  150  and handle portions  200   a, b . The two pieces of the lock button fit together with button locking formations and button locking slots which cause both portions of the lock button to be rotationally fixed to one another. Additionally, handle locking formations formed on an exterior of the lock button mate with handle locking grooves formed in an aperture of the handle portions to rotationally fix the lock button to the handle. Finally, a blade locking formation formed on the second portion  300   b  of the lock button selectively interacts with one of a plurality of blade locking grooves extending from an aperture in the blade holder, thereby rotationally fixing the blade holder relative to the handle. The forgoing aspects of the knife  100  will be discussed and disclosed in greater detail below. 
         [0022]      FIG. 3  is an enlarged view of the second portion  300   b  of the lock button and  FIG. 4  is a top view of the assembled lock button showing the first and second portions  300   a - b  but not showing the handle portions or the blade holder which would be housed between the button portions. As illustrated in  FIGS. 2-4 , first portion  300   a  of the lock button includes button locking formations  310  constructed and arranged to mate with button locking slots  320  formed in second portion  300   b  of the lock button  300 . The interaction of the formations  310  and slots  320  prevents rotation between the button portions. 
         [0023]    Also visible in  FIGS. 2 and 3  are handle locking formations  210  formed on an outer surface of the first and second lock button portions. The purpose of the handle locking formations  210  is to rotationally fix the lock button  300  to the handle portions  200   a ,  200   b . Visible in  FIGS. 2 and 5 , each handle portion includes an aperture  220  formed therein and four radially extending, handle locking grooves  225  extending from the aperture. When assembled, the formations  210  and grooves  225  between the lock button  300  and handle portions keeps the lock button rotationally fixed to the handle. 
         [0024]    Visible in  FIGS. 2 and 6  is an aperture  160  formed in the blade holder  150  of the knife  100 . Extending from the aperture  160  are four blade locking grooves  175  disposed around a perimeter of the aperture in a way intended to correspond to certain pivotal/angular relationships between the blade holder  150  and the handle. The blade locking grooves  175  are constructed and arranged to selectively engage a blade locking formation  350  which is formed on the second portion  300   b  of the lock button  300 . The blade locking formation is visible in  FIGS. 2-4  and appears similar in shape to the handle locking formations  210  formed on the lock button. However, the blade locking formation is longer than the other formations permitting it to extend through handle portion  200   a  to the blade holder  150  and into contact with a selected blade locking groove  175 . 
         [0025]    As illustrated in  FIGS. 7 and 8 , the blade locking formation  350  is normally biased into a position of interference with one of the blade locking grooves  175  (as it appears in  FIG. 7 ) due to a spring member  315  disposed on the first portion  300   a  of the lock button  300  that urges the blade locking formation  350  into the area of the blade holder and, if it is aligned with a blade locking groove  175 , into the groove where it will lock the blade holder and blade in a predetermined rotational position relative to the handle. As illustrated in  FIG. 7 , the blade locking formation  350  is located in one of the blade locking grooves  175  of the blade holder and remains held in that position due to the spring member which urges the lock button  300  towards one side of the knife handle. 
         [0026]      FIG. 8  is a section view of the knife of  FIG. 7  with the blade holder in an unlocked position and free to rotate about a pivot point at lock button  300  due to the retracted position of the blade locking formation  350 . In  FIG. 8 , the lock button  300  is in a depressed position whereby the spring  315  is compressed and the lock button  300  is moved in a direction perpendicular to the long axis of the knife whereby the blade locking formation  350  is displaced from the area of the blade holder  150  and its blade locking grooves  175 . The blade holder in this position is free to be rotated relative to the handle. In operation, the lock button  300  is depressed by a user against the spring  310  and the blade holder  150  can then be adjusted to a variety of positions and then, when the button is released, locked in that position due to the blade locking formation&#39;s engagement with a given blade locking groove  175 . 
         [0027]      FIGS. 9 and 10  are two views that specifically illustrate the operation of the lock button  300  when it is operated by a user and the selective location of the blade locking formation  350  relative to the blade holder  150  (not shown). Each figure shows the inner surface of handle portion  200   a  and the second portion  300   b  of the lock button  300  located within the aperture  220  formed in the handle portion.  FIG. 9  specifically illustrates the blade locking formation  350  in a position whereby it would extend into a blade locking grove  175  of the blade holder  150 , thereby locking the blade holder  150  in a predetermined rotational position related to the handle. In  FIG. 10 , the same operational parts of the knife are shown as they would appear when the lock button  300  is depressed against the spring  315  and the blade locking formation  350  is displaced into a groove  225  of the handle portion  200   a  and away from the blade holder and the blade locking grooves  175 . 
         [0028]    Various locked positions of the blade relative to the knife handle are illustrated in  FIGS. 11 through 14 . Each position relates to a position of the blade locking formation  350  in one of the blade locking grooves  175 . For example,  FIG. 12  illustrates the blade holder and blade locked an intermediate position between fully opened and fully closed. A user might lock the knife in the position to perform certain cutting jobs. To move the blade to another position, the lock button  300  is depressed and the blade holder  150  is free to move to another location where it will be locked at an angle relative to the handle due to the locking formation&#39;s movement into a particular blade locking groove  175  when the lock button  300  is released. 
         [0029]    While the knife described in detail herein is a utility knife with a blade holder, the locking mechanism described and claimed is equally usable with any knife having a folding blade with a pivot point between the blade and the handle. Or instance, the aperture and blade locking grooves referred to in the blade holder could just as easily be formed directly in a first end of a blade. 
         [0030]    While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.