Abstract:
A handheld knife having a non-rotating retractable blade which reversibly travels between a position of storage within the knife handle and an extended position of use in a direction which is substantially perpendicular to a longitudinal axis of the knife handle.

Description:
FIELD OF THE INVENTION 
     The present invention relates to cutting instruments, and more particularly handheld knives with retractable blades. 
     BACKGROUND OF THE INVENTION 
     Cutting instruments, and more specifically handheld knives, have been used for generations and even centuries by hunters, craftsmen and soldiers. These knives are generally characterized by a metallic blade with a sharpened cutting edge and a handle to both hold the blade and to be held by the user for safety purposes. 
     Fixed blade knives extend from the handle and are incapable of being folded or otherwise storing the blade in a position where the knife blade cutting surface is not exposed. Thus, these knives can be dangerous if not used and stored properly. 
     Handheld knives which store the knife blade in a non-exposed position during non-use are generally characterized by three different types. These include folding knives, switchblade knives and stilettoes. 
     With a folding knife, the blade generally rotates about a pivot pin near the front of the knife handle between a first extended position and a second closed position. In the first open position the knife blade is substantially coextensive with the longitudinal axis of the knife handle. In the second closed position, all or a portion of the knife blade cutting edge is received within a cavity defined in the handle which substantially prevents the cutting edge of the knife blade from being exposed. With a typical folding knife, the blade is opened and closed between the first extended position and second closed position manually. Unfortunately, folding knives may be cumbersome since a large portion of the blade is still exposed even when the blade is in a closed position and thus has the potential of inadvertently opening if the blade is caught or snagged. 
     Switchblade knives are constructed in a similar manner to folding knives with the knife blade rotating about a pivot pin near the front of the knife handle. However, they are spring loaded, and thus open very quickly when a button is pressed or a switch is activated which releases the spring. These knives are illegal in most states and foreign countries due to their inherent danger. 
     Stilettoes are distinct from folding knives and switchblade knives since the knife blade does not rotate about a pivot pin near the front of the handle. Rather, the blade is stored within the knife handle and is extended to a first position of use by the blade being thrust forward in a direction which is substantially coextensive with the knife handle. Thus, the knife blade does not rotate about a pivot pin and is exposed for use with the knife blade extending directly outward from the cavity within the handle. The knife blade may be extended manually or more commonly mechanically by the use of a spring. Stilettoes are also illegal in many states and countries, since the blade is concealed and the mechanical energy provided by the spring can make them inherently dangerous. 
     Cutting instruments known as an “ulu” knife have also known in the art and are characterized by a fixed, nonmoving blade having a longitudinal axis consistent with the length of the knife handle. These types of knives have been used extensively by Eskimos and many native American Indians. The “ulu” knife blade is unique from most knives since the cutting edge is positioned substantially parallel to the longitudinal axis of the knife handle. This orientation makes the knife well suited for skinning animals and for use in a “rolling” motion when a downward force is applied. Unfortunately, these non-folding knives are bulky to carry and have an exposed cutting edge at all times, thus requiring the use of a sheath for safety purposes. 
     Thus, many of the knife designs discussed above are impractical, cumbersome to carry, are potentially dangerous, or are illegal to own. Further, due to the generally linear shapes of most knife blades, they are not practical for use for skinning or chopping with a rolling motion when a more arcuate shaped cutting edge is preferred. Finally, the pointed tip on most conventional blades can be dangerous if a person were to inadvertently fall on the tip. What is needed is a safe, handheld knife with a blade positioned substantially parallel to the longitudinal axis of the handle which can travel between a first extended position of use and second closed position with the blade cutting edge stored in the handle in a safe, efficient manner. 
     SUMMARY OF THE INVENTION 
     It is thus an object of the present invention to provide a lightweight, handheld cutting instrument with a retractable blade that travels between a first position of use with the blade cutting edge exposed and a second retracted position where the blade is protected within a cavity of the knife handle and the blade cutting edge is not exposed. 
     Thus, in one aspect of the present invention a knife is provided with a handle that has a cavity for receiving a knife blade along a substantially longitudinal axis extending from the front end of the knife handle to the rear end of the knife handle. The knife blade, having a similar longitudinal length extending from a first end to a second end of the knife blade, retracts into the knife handle at a substantially right angle to the longitudinal axis of the knife handle and blade. 
     It is yet another aspect of the present invention to provide a portable, lightweight folding knife which can be manually opened and closed with one hand. Thus, in another aspect of the present invention, a mechanism is provided which allows the blade to be reversibly extended and retracted from the knife handle with pressure applied merely from a user&#39;s thumb or finger. 
     It is yet another aspect of the present invention to provide a portable cutting instrument which is compact in size, safe, yet carries a blade cutting edge with a sufficient length to be useful for cutting, skinning, chopping and other purposes commonly required of handheld cutting instruments. Thus, in one aspect of the invention, a knife with a retractable blade is provided with the cutting edge of the blade extending substantially the entire longitudinal length of the knife handle. 
     It is a further object of the present invention to provide a knife with a blade with an arcuate geometric shape which extends substantially from a first end of the knife blade cutting edge to a second edge of the knife blade cutting edge. This geometric shape of the knife blade makes the knife especially useful for certain operations such as skinning an animal, chopping and the blade to be used in a fashion which is not fatiguing to the user&#39;s hand, wrist or arm. Furthermore, with this type of blade configuration (without a pointed end) the blade cannot be used for stabbing and is thus significantly safer than typical handheld knives. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevation view of the knife with the blade enclosed within a cavity in the handle. 
     FIG. 2 is a left end view of the knife shown in FIG. 1; 
     FIG. 3 is a bottom plan view of the knife shown in FIG. 1; 
     FIG. 4 is a rear elevation view of the knife shown in FIG. 1; 
     FIG. 5 is a front elevation view of the knife shown in FIG. 1, with the blade extended to a first position of use; 
     FIG. 6 is a front elevation view of an alternative knife design with the front scale removed for clarity purposes; 
     FIG. 7 is a front elevation view of an alternative knife design with the front scale removed for clarity purposes; and 
     FIG. 8 is a front elevation view of an alternative knife design with the front scale removed for clarity purposes. 
     FIG. 9 is a front elevation view of an alternative knife design with a thumb stud interconnected to the knife blade. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Subtitles 
     Referring now to the drawings, FIGS. 1 through 5 illustrate one particular embodiment of the present invention showing the knife blade in both a retracted position for storage purposes and a second extended position of use. FIGS. 1 through 4 depict the knife  2  with the knife blade  10  received within the handle cavity  18  of the knife. FIG. 5 shows the knife  2  with the knife blade  10  extended in a position of use. In general the hand held knife  2  comprises a knife handle  4  which is comprised of a front scale  28  and rear scale  30  which defines a handle cavity  18  for receiving a knife blade  10 . The knife handle is generally comprised of a handle front end  6 , a handle rear end  8  and a handle aperture  26  which allows a user of the knife to engage a knife blade depression  20 . Contrary to the positioning of most knife blades in knife handles, the present invention incorporates a knife blade  10  which travels in a direction substantially perpendicular to the longitudinal axis of the knife handle  4 . Thus, as seen in FIG. 1, when pressure is applied to the blade depression  20  by a user&#39;s thumb, the knife blade  10  is extended outward to a first position of use as shown in FIG.  5 . 
     When the knife blade  10  is not being used, the knife blade  10  can be retracted back into the knife handle cavity  18  by pressure being applied to the blade depression  20  in the opposite direction. As seen in FIG. 2, the knife blade  10  in a retracted position is received in the knife handle cavity  18  for safety purposes to assure that the blade cutting edge  16  is not exposed. 
     To accommodate the attachment of the knife to a user&#39;s belt, pocket or other object, a clip  42  is interconnected to either the front scale  28  or rear scale  30 . Preferably, the knife clip  42  is positioned on the scale which is opposite the handle aperture  26 . The clip  42  is preferably constructed of a metallic material for strength, although other material such as rigid plastics may be used to achieve the same purpose. The clip  42  is attached to the knife handle  4 , i.e. front scale  28  or rear scale  30  by means of a stud  44 . The stud  44  is preferably made of stainless steel, or other metallic materials although plastics may functionally serve the same purpose. Alternatively, the clip may be integrally molded into one of the scales as a single piece, thus eliminating the need for a stud  44  or pin. 
     Referring back to FIG. 1, one particular embodiment of the present invention is shown which accommodates the movement of the knife blade  10  from a first extended position of use to a second retracted position with the knife blade cutting edge  16  received within the knife handle  4 . In this particular embodiment, one or more positioning slots  40  are cut out of the knife blade  10  to accommodate receiving one or more studs  46  which are interconnected to either the front scale  28 , the real scale  30 , or both. Alternatively, the positioning slots  40  may be cut out of either the front scale  28 , rear scale  30 , or both while the stud(s)  46  is interconnected to the knife blade  10  to engage the positioning slots  40 . In use, when pressure is applied downwardly on the blade depression  20  in a direction toward the knife blade cutting edge  16 , the stud  46  rides within the positioning slot  40  to allow movement of the knife blade  10  in a downward direction, thus exposing the knife blade cutting edge  16 . When the stud  46  reaches the end of the positioning slot  40 , it becomes engaged in the slot hook arm  52  to effectively lock the blade and to prevent any inadvertent movement as shown in FIG.  5 . As identified in the drawings, when the blade is in a second retracted position within the blade handle, the blade cutting edge  16  is not exposed for obvious safety purposes. 
     The knife blade  10  as shown in FIGS. 1 through 8 generally has a longitudinal axis which is consistent with the longitudinal axis of the knife handle  4 . On the lower end of the knife blade is a knife cutting edge  16  which may have a typical sharpened blade edge or a serrated blade edge as shown in the drawings. Preferably, the knife blade cutting edge  16  has an arcuate shape from the knife blade first end  12  to the blade second end  14 . This arcuate shape of the knife blade  10  allows the knife blade  10  to be used in a rolling motion when cutting any particular item which makes it very functional for cutting certain objects such as vegetables or for removing the skin of an animal. 
     Referring now to FIG. 5, the knife blade  10  is shown in a first extended position outside the handle cavity  18  in a position of use. When the blade is extended, the studs  46  are positioned within the slot hook arms  52  to prevent the knife blade  10  from retracting into the knife handle cavity  18  inadvertently. Alternatively, other types of locking mechanisms can be used such as a stud extending through the blade, locking cams or other locking devices commonly known in the art. As can additionally be seen in this position, the blade depression  20  is now positioned at the lower end of the handle aperture  26 . As the handle is grasped on the upper portion by a user, the knife blade  10  can be rolled back and forth or used in a sweeping motion for skinning purposes or other similar purposes. 
     Referring now to FIG. 6 through 8, alternative blade retraction mechanisms are provided for allowing the blade to travel between the first extended position of use and the second retracted position. In each of these figures, the front scale  28  has been removed for illustration purposes to more clearly identify the position of the knife blade  10  and the knife handle  4  and the blade retraction mechanism. Additionally, in each of the alternative embodiments shown the blade depression  20  has been replaced with a blade aperture  22  which is an aperture extending entirely through the knife blade  10  rather than merely being a blade depression  20  for engagement by a user&#39;s thumbs. Additionally, the blade aperture  22  is positioned centrally between the blade first end  12  and the blade second end  14  rather than in a forward position as shown in FIGS. 1 through 5. 
     Referring again to FIG. 6, the blade retraction mechanism in this embodiment generally comprises a pair of traveling arms  50  which are interconnected to a pin or stud  46  which is positioned near the upper edge of the knife blade  10  at a position approximately midway between the blade lateral edges  54 . The blade  10  is additionally interconnected to two or more alignment pins  38 , which are positioned in distinct positions on the knife blade  10  below the upper stud  46  or pin. The alignment pins  38  travel within corresponding positioning slots  40  which are positioned in either the front scale  28 , the rear scale  30 , or both. During use, as force is applied downward to the blade aperture  22  in the direction of the blade cutting edge  16 , the traveling arms  50  move downward pushing the alignment pins  38  in an outwardly direction, thus allowing the knife blade cutting edge  16  to travel downward and out of the blade cavity  18 . Once the blade is in its completely extended position, the traveling arms  50  extend into a fixed position. To prevent the inadvertent movement of the knife blade from its extended position, a locking mechanism may be incorporated which utilizes a locking pin, cam, or other similar device commonly known in the art. To move the knife blade from the first extended position to a second retracted position within the knife handle, force is applied to the blade aperture  22  in an upward direction opposite the blade cutting edge. As force is applied, the alignment pins  38  move inward within the positioning slots  40  as the traveling arms move upward to the position shown in FIG.  6 . 
     Referring now to FIG. 7, an alternative embodiment of the present invention is shown which incorporates a pair of positioning gears  32  interconnected to either the front scale  28 , the rear scale  30  or both. In operable relationship with each of the positioning gears  32  are positioning teeth  34  which are cut into each of the lateral edges of the knife blade  10 . When downward pressure is applied to the blade aperture  22  in a direction toward the blade cutting edge  16  by a user&#39;s thumb, the positioning gears  32  engage the positioning teeth  34  of the knife blade  10  and the knife blade extends outside of the handle cavity  18 . Correspondingly, when the knife blade is desired to be in a retracted position, pressure is applied upward on the blade aperture  22  in a direction opposite the blade cutting edge  16 , thus allowing the positioning teeth  34  to operatively engage the positioning gears  32  until the knife blade  10  moves upward into the knife cavity. To facilitate locking the blade into a first extended position of use a locking mechanism such as a stud may be utilized which extends from the handle through the knife blade  10 . Alternatively, a biased cam mechanism may be used as well as other locking devices commonly known in the art. 
     Referring now to FIG. 8, an alternative embodiment of the present invention is shown wherein the knife blade  10  actually pivots about a pivot pin  48  which is positioned near the handle front end  6 . Thus, as pressure is applied by a user to the blade aperture  22 , the blade second end  14  rotates about the blade pivot pin  48  in a clockwise rotation. Thus, the blade second end  14  becomes exposed first from the blade cavity while the remainder of the blade follows as the blade is pivoted around the pivot pin  48 . To facilitate locking the blade into position, it is anticipated that a stud, cam or other similar type device can be employed as discussed above. 
     While various embodiments of the present invention have been described in detail, it is apparent that further modifications and adaptations of the invention will become apparent to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the sphere and scope of the present invention. For clarity, the numbering of the various components identified in the figures are provided herein. 
     COMPONENT LIST 
     
       
         
               
               
               
               
             
           
               
                   
               
               
                 # 
                 Component 
                 # 
                 Component 
               
               
                   
               
             
             
               
                 02 
                 Knife 
                 30 
                 Rear Scale 
               
               
                 04 
                 Knife Handle 
                 32 
                 Positioning Gears 
               
               
                 06 
                 Handle Front End 
                 34 
                 Positioning Teeth 
               
               
                 08 
                 Handle Rear End 
                 36 
                 Alignment Rods 
               
               
                 10 
                 Knife Blade 
                 38 
                 Alignment Pins 
               
               
                 12 
                 Blade First end 
                 40 
                 Positioning Slots 
               
               
                 14 
                 Blade Second End 
                 42 
                 Clips 
               
               
                 16 
                 Blade Cutting Edge 
                 44 
                 stud 
               
               
                 18 
                 Handle Cavity 
                 48 
                 Pivot Pin 
               
               
                 20 
                 Blade Depression 
                 50 
                 Traveling Arms 
               
               
                 22 
                 Blade Aperture 
                 52 
                 Slot Hook Arm 
               
               
                 24 
                 Blade Stud 
                 54 
                 Blade Lateral Edge 
               
               
                 26 
                 Handle Aperture 
                 56 
                 Blade Upper Edge 
               
               
                 28 
                 Front Scale 
                 58 
                 Handle longitudinal axis 
               
               
                   
                   
                 60 
                 thumb stud