Abstract:
A trigger acting upon a lever pivotally attached to a body urges the lever to overcome a magnetic force attracting the lever to a segment of the body and to pivot from a first position to a second position, which trigger is not positionally moved until the magnetic force is overcome. A jaw has a first position for retaining a bowstring and is maintained in the first position by the lever being in the first position. When the lever pivots to the second position, the jaw under influence of a force imposed by the bowstring pivots to a second position and releases the bowstring. A further pair of magnets may be used to create an opposing magnetic force to further urge maintenance of the lever in the first position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is related to and claims priority of a provisional application entitled “MAGNETIC ARCHERY RELEASE”, filed Sep. 2, 2004, and assigned Ser. No. 60/607,137, disclosing an invention by the present inventor. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to bowstring releases and, more particularly, to a magnetic bowstring release.  
         [0004]     2. Description of Related Prior Art  
         [0005]     Mechanical archery bowstring releases have become increasingly popular in recent years because they provide more uniform control of a bowstring and increase accuracy by effecting a consistent, controlled release of an arrow over that of a manual release. Bowstring releases are typically used to maintain the bowstring in a cocked position in which the bowstring is flexed against the tension of the bow for propelling the arrow supported on the bowstring. When a drawn arrow is released from a release mechanism, the release of the bowstring is usually relatively rapid and at a point approximately in line with the centerline of the bow so that the bowstring delivers most of its thrust directly along the major axis of the arrow. When tabs or fingers are used to release a bowstring, the bowstring tends to roll off the fingers or tab and be deflected sideways during release. The bowstring then tends to follow a serpentine path and fails to maximize the energy delivery directly along the major axis of the arrow.  
         [0006]     The majority of the bowstring releases have a body or casing which houses the sear and trigger mechanisms. The body is typically a cylindrical or rectangular configuration with the pivotable jaws of the sear mechanism positioned at one end and a trigger located along the length of the body. The jaws and trigger of the bowstring release are traditionally secured to the body with linkages or pins, which serve as pivot mechanisms for the jaws and trigger.  
         [0007]     It has been found that many commercial bowstring releases load up severely as the pulling force on the bowstring is increased. Loading up is a phenomenon whereby the force required of the archer to pull the trigger and release the bowstring increases as the effective draw weight of the bow increases. Thus, at higher effective draw weights, the archer must pull harder on the trigger, perhaps causing a decrease in sensitivity and performance. A harder trigger pull may also cause a jerking trigger release motion, causing erratic arrow flight.  
         [0008]     There are two commonly used trigger sensitivity adjustment mechanisms. In one mechanism, the depth of engagement of sear elements is varied. This affects trigger pull length, also known as trigger travel distance, and indirectly affects the pull force required by making the trigger travel farther to disengage the sear, which in turn increases the sliding friction. Another mechanism is a single roller on one of a pair of sear elements. The roller is used to reduce friction between the sear elements. Adjustment is related to positioning the roller&#39;s center in relation to the edge of an angled slot in the trigger.  
       SUMMARY OF THE INVENTION  
       [0009]     A lever supporting a trigger of a magnetic release is magnetically biased to maintain a pivotally mounted jaw in engagement with a bowstring. To effect a release of the bowstring, pressure is applied to the trigger, which trigger does not move until the applied force overcomes a magnetic force acting upon the lever. Until the magnetic force between the lever and the magnet is overcome, there is no movement of the trigger and the archer may terminate actuation of the trigger without any detrimental result. The body of the magnetic release may be either attached to the archer&#39;s wrist by a wrist strap to permit engaging the body with one&#39;s thumb and leaving the forefinger free to actuate the trigger. In a second embodiment, the mechanism may be retained by the archer&#39;s fingers and the trigger may be actuated by the archer&#39;s thumb. In variants of the invention, the magnet may be positionally adjusted to vary the degree of magnetic force exerted. In other variants, the number of magnets may be increased, including the use of a pair of opposing magnets to restrain movement of the lever, to provide various levels of control over the degree of force that must be applied to pivotally move the lever.  
         [0010]     It is therefore a primary object of the present invention to provide a magnetic force to control a mechanism for releasing a bowstring.  
         [0011]     Another object of the present invention is to provide a magnetically actuated bowstring release attached to a user&#39;s wrist with a wrist strap to provide the force necessary to draw the bowstring.  
         [0012]     Still another object of the present invention is to provide a magnetically actuated bowstring release held by the fingers of an archer.  
         [0013]     Yet another object of the present invention is to provide a pivotable lever magnetically attracted to the body of the bowstring release to disengage a pivotable bowstring retaining jaw when the magnetic force acting upon the lever is overcome by a force exerted on a trigger.  
         [0014]     A further object of the present invention is to provide a magnetically actuated release for a bowstring that includes a trigger which does not move until the force applied to the trigger overcomes a magnetic force retaining a lever supporting the trigger.  
         [0015]     A yet further object of the present invention is to provide a magnetically actuated release for a bowstring having magnets positionally adjustable to provide a selected magnetic force.  
         [0016]     A still further object of the present invention is to provide a magnetically actuated bowstring release that includes a plurality of magnets operating in concert to provide a selectable magnetic force that must be overcome to trigger release of the bowstring.  
         [0017]     A still further object of the present invention is to provide a method for releasing a bowstring with a magnetic release.  
         [0018]     These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The present invention will be described with greater specificity and clarity with reference to the following drawings, in which:  
         [0020]      FIG. 1  illustrates the magnetic release being hand held;  
         [0021]      FIG. 2  illustrates opening of the jaw of the magnetic release in response to trigger movement;  
         [0022]      FIG. 3  is a left side view of the magnetic release;  
         [0023]      FIG. 4  is a right side view of the magnetic release;  
         [0024]      FIG. 5  is a partial cut away isometric view of the magnetic release in the closed position;  
         [0025]      FIG. 6  is a partial cut away isometric view of the magnetic release in the open position;  
         [0026]      FIG. 7  illustrates the magnetic release in the closed position;  
         [0027]      FIG. 8  illustrates the magnetic release with force being applied to the trigger;  
         [0028]      FIG. 9  illustrates the magnetic release in the open position;  
         [0029]      FIG. 10  illustrates four variants of a magnet useable with the magnetic release;  
         [0030]      FIG. 11  illustrates a first variant of the magnetic release;  
         [0031]      FIG. 12  illustrates the use of a pair of magnets in the first variant shown in  FIG. 11 ;  
         [0032]      FIG. 13  illustrates a further pair of magnets useable in the first variant illustrated in  FIG. 11 ;  
         [0033]      FIG. 14  illustrates the use of three magnets in the variant shown in  FIG. 11 ;  
         [0034]      FIG. 15  illustrates the use of several sets of magnets useable in the variant illustrated in  FIG. 11 ; and  
         [0035]      FIG. 16  illustrates a second variant of the magnetic release.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0036]      FIG. 1  illustrates a magnetic release  10  held by a user. In particular, a wrist strap  12  secured to body  14  is secured to the wrist of the user and upon the user drawing his/her arm back, will translate this motion to the magnetic release to draw a bowstring. The user&#39;s thumb  15  may be placed within an arced indentation  16  formed in the top of body  14 . A trigger (not shown) extends downwardly from the body and the user&#39;s forefinger  18  applies pressure to the trigger to effect release of a bowstring captured between a jaw  20  and an anvil  22 . A pin  24  serves as a pivot axis for the jaw. Similarly, a further pin  26  serves as the pivot axis for a trigger operated lever (not shown) that releases jaw  20 . A slot  27  of magnet  28  (not shown) positions the magnet that provides a magnetic force upon the lever to restrain movement of the lever and release of jaw  20 , unless a sufficient force is applied to the trigger. Upon application of such a force, jaw  20 , as illustrated in  FIG. 2 , pivots about pin  24  and releases a bowstring captured between anvil  22  and the jaw.  
         [0037]     Referring jointly to  FIGS. 3, 4 ,  5  and  6 , further details of magnetic release  10  will be described. Body  14  includes an aperture  30  for receiving wrist strap  12  illustrated in  FIGS. 1 and 2 . Thereby, the wrist strap is firmly attached to body  14  of magnetic release  10  and a movement of the wrist strap by a user moving his/her arm will result in commensurate movement of the magnetic release. Jaw  20  includes a slot  32  for receiving a bowstring and jaw  22  captures the bowstring therewith when the jaw is in the closed position as shown in  FIGS. 3, 4  and  5 . A trigger  34  is attached to and extends from a pivotable lever  36 , which lever pivots about pin  26 , as described above. As particularly shown in  FIGS. 5 and 6 , a magnet  28  is retained within a commensurately configured cavity  42  in body  14 . Preferably but not necessarily, the magnet is a solid magnet. As shown, the magnet may be in the form of a disk having opposed poles as is conventional. The rotational position of the magnet may be modified by screwdriver engaging slot  27 . The rotational position of the magnet may be set by a set screw  44 . Trigger  34  may be formed by a sleeve  50  bearing against lever  36  and retained in place by a bolt  52  penetrably engaging the sleeve into threaded engagement with the lever, as illustrated. Lever  36  may support a rod  54  extending therefrom. Preferably, this rod is of low friction material, such as material sold under the trademark Teflon or the like. In the closed position of jaw  20 , as illustrated in  FIG. 5 , rod  54  bears against a pin  56 , or the like, extending from jaw  20 , which pin is preferably also of low friction material.  
         [0038]     Lever  36  is retained in the position shown in  FIG. 5  by magnet  28  creating a magnetic force to draw lever  36  there against, as illustrated; it is understood that the lever must be of magnetically responsive material, such as steel or the like. As a rearward force is applied to trigger  34 , as representatively illustrated by arrow  58 , no pivotal movement about pin  26  of the trigger or the lever will occur until the magnetic force between magnet  28  and the lever is overcome. When the magnetic force is overcome, an airspace will develop between the magnet and the lever and the magnetic force of the magnet acting upon the lever will be significantly reduced. Thereafter, both the trigger and the lever will rotate about pin  26 . Such rotation of the lever will result in rod  56  slidably disengaging from pin  56 .  
         [0039]     In the closed position of jaw  20 , as illustrated in  FIG. 5 , the force of the bowstring acting upon the jaw as a result of its position within slot  32  will tend to urge rotation of the jaw away from anvil  22 . However, such rotation is prevented by the interfering engagement between rod  54  and pin  56 . Upon the pivotal movement of lever  36  and rod  54  extending therefrom, end  60  of the rod will slide past pin  56  and jaw  20  will become free to rotate about pin  24 . The force of the bowstring acting upon the jaw, as described above, will result in pivotal movement of the jaw to the open position illustrated in  FIG. 6 . In this position of the jaw, the bowstring is released from in between the jaw and the anvil.  
         [0040]     To vary the magnetic force exerted by magnet  28  upon lever  36 , the magnet may be rotated from one of the poles bearing against the lever in the closed position shown in  FIG. 5  in which position the magnet exerts a maximum magnetic retentive force upon the lever. This will require the greatest force to be exerted upon trigger  34  until release can be effected. By rotating the magnet to a position where a part of the magnet intermediate the two opposed poles is in contact with the lever, the magnetic force acting upon the lever can be reduced. Such reduced magnetic force will require a lesser force to be exerted upon trigger  34  to effect release of jaw  20 . Once the position of magnet  28  has been adjusted to provide a magnetic force acting upon lever  36  commensurate with the degree of force a user wishes to exert upon trigger  34  to effect a release, the magnet is locked in place by set screw  44 . It is to be understood that the magnetic force exerted upon the lever can be reset by simply loosening set screw  44  and rotating the magnet to increase or decrease the magnetic force acting upon the lever.  
         [0041]      FIG. 7  schematically illustrates further details of magnetic release  10 . In particular, it illustrates lever  36  pivotally mounted upon pin  26 . The lever includes a surface  64  extending away from cavity  66  in body  14 . Thereby, lever  36  may pivot clockwise (as illustrated) until surface  64  contacts the base of cavity  66 . As shown, bowstring  68  is captured in slot  32  of jaw  20 .  
         [0042]      FIG. 8  illustrates, as represented by arrow  70 , the application of a trigger force upon trigger  34 . The application of such a force will not result in a commensurate movement of the trigger or of lever  36  until the force, translated through the lever, is sufficient to overcome the magnetic attraction between magnet  28  and the lever. As the force on trigger  34  increases, the magnetic force between magnet  28  and lever  36  will be overcome. At that instant, trigger  34  and attached lever  36  will pivot about pivot point  26 , as illustrated in  FIG. 9 . Such pivotal movement will continue until surface  64  of the lever comes in contact with cavity  66 , as illustrated. Simultaneously, rod  54  will become disengaged from pin  56 . Upon such disengagement, jaw  20 , under urging of bowstring  68 , will cause the jaw to pivot in the direction indicated by arrow  72 . Thereafter, the bowstring will become released and travel in response to the forces exerted by the bow, as depicted by arrow  74 .  
         [0043]     As partially illustrated in  FIGS. 5, 6 ,  7 ,  8  and  9 , body  14  includes a slot  76 . This slot receives, in part, jaw  20 . The slot, in conjunction with pin  24 , prevents skewing of the jaw that might cause it to bind before or during release.  
         [0044]     To reset magnetic release  10 , jaw  20  is opened, as depicted in  FIG. 9 . Upon placement of the bowstring within slot  32  in the jaw, the jaw is pivoted to the closed position shown in  FIG. 8 . The force of magnet  28  may be sufficient to draw lever  36  into engagement therewith; if not, movement of the trigger in a direction opposite to that of arrow  70  (see  FIG. 8 ) (or manually imposed pivotal movement of lever  36 ) will cause lever  36  to be placed adjacent and essentially in contact with magnet  28 , which magnet will retain the lever in place.  
         [0045]      FIG. 10  illustrates the potential for using differently sized magnets to be lodged within cavity  42  (see  FIGS. 4, 5  and  6 ). Such differently sized magnets are expected to urge correspondingly different magnetic forces acting upon lever  36 . Depending upon the material of any one of magnets  80 ,  81 ,  82  or  83  the degree of magnetism of a magnet might increase or decrease. Thus, not only can differently sized magnets be used, but magnets of the same size but of different magnetic properties may be used.  
         [0046]      FIG. 11  illustrates a first variant  90  of a magnetic release for a bowstring. This variant embodies the operational features of magnetic release  10  discussed above but the configurations of certain of the components are different. Body  92  includes three scalloped surfaces,  94 ,  96  and  98  for receiving and gripping by a user&#39;s forefinger, middle finger and ring finger, respectively. A trigger  100  is depressed by a user&#39;s thumb. The trigger is attached to a lever  102  by a bolt  104  or the like. The lever is pivotable about a pin  106  extending from body  92 . A jaw  108  includes a slot  110  for receiving and retaining a bowstring  111 . An anvil  112 , similar functionally and to some extent structurally with anvil  22 , includes a slot  114  formed in the anvil; for clarity of illustration, only side  116  of the slot is shown. However, it is to be understood that a slot  76 , like that illustrated in  FIG. 11 , could also be used. Jaw  108  is rotatable about a pin  118  extending from body  92 .  
         [0047]     An indentation  120  is formed in jaw  108  to receive and mate with end  122  of lever  102 . Upon placement of end  122  within indentation  120 , as illustrated, counterclockwise rotation of jaw  108  is precluded due to the interference between the indentation and the end of the lever. That is, when jaw  108  has captured a bowstring, the force exerted by the bowstring will tend to cause the jaw to rotate a about pin  118  in a counterclockwise direction. Such rotation is precluded by end  122  of the lever. The lever is magnetically retained in the position illustrated in  FIG. 11  by a magnet  124  mounted in body  92 . Until a force sufficient to overcome the magnetic attraction between magnet  124  and lever  102  is present, no movement of the lever will occur.  
         [0048]     To release the bowstring from within jaw  108 , a user would push upon end  126  of trigger  100 . No movement of the lever occurs until this pushing force is sufficient to overcome the magnetic force of magnet  124  acting upon lever  102 . When the magnetic force is exceeded, pivotal movement of the lever in the counterclockwise direction, as represented by arrow  127 , would occur and the lever would move under the force exerted upon end  126  until the lever abuts against surface  128  of body  92 . Thus, this surface limits the degree of counterclockwise movement of the lever. When the lever is rotated counterclockwise, end  122  will become disengaged from indentation  120 . Upon such disengagement, the force exerted by bowstring  111  captured in slot  110  of jaw  108  will cause the jaw to rotate counterclockwise about pin  118 . Upon sufficient rotation of the jaw to clear slot  114 , bowstring  111  will be released.  
         [0049]     Referring to  FIG. 12 , there is shown a variation of the magnets exerting a magnetic force upon lever  102 . A first magnet  130  maybe mounted in body  92  to exert a magnetic force upon the lever. A second magnet  132  may be mounted in conjunction with the lever to magnetically coact with magnet  130 . These magnets are mounted to attract one another and thereby increase the magnetic force tending to prevent counterclockwise rotation of the lever. As a result, a greater force would have to be exerted upon trigger  100  to effect release of a bowstring  111  captured by jaw  108 . Alternatively, these magnets may be mounted to magnetically oppose one another. Such orientation would have two effects. First, it would reduce the amount of force necessary to cause rotation of lever  102 . Second, once the contact between lever  102  and magnet  130  is broken, the opposing magnetic forces would enhance further rotation of the lever to permit opening of jaw  108 .  
         [0050]      FIG. 13  illustrates a second embodiment of first variant  90 . Herein, a first magnet  134  is mounted upon lever  102 . A second magnet  136  is mounted upon body  92 . By orienting these two magnets to magnetically oppose one another, counterclockwise pivotal movement of lever  102  about pin  106  in response to a force exerted upon end  126  of trigger  100  would be increased as a function of the opposing magnetic forces. Magnet  136  may be mounted in a slot  138  to accommodate repositioning of the magnet to vary the opposing magnetic force between the two magnets. Thereby, a user can modify the amount of force on trigger  100  necessary to effect release of bowstring  111  from jaw  108 .  
         [0051]      FIG. 14  illustrates a fourth embodiment of first variant  90 . In this embodiment, three magnets are used. Magnet  140  is mounted on body  92  adjacent and essentially in contacting relationship with lever  102 . Thereby, the magnet provides a magnetic force to retain the lever there against. A second magnet  142  may be mounted on lever  102  and a third magnet  144  may be mounted upon body  92 . As illustrated, magnet  144  may be mounted within a slot  146  to accommodate positional adjustment of this magnet. By orienting magnets  142  and  144  to provide opposing magnetic forces, a magnetic resistance will be present to resist counterclockwise movement of lever  102  about pin  106 . The degree of this magnetic resistance may be modified by repositioning magnet  144  within slot  146  to be closer to or further away from magnet  142 . With this arrangement, magnet  140  creates a magnetic force to urge lever  102  into a clockwise position. Simultaneously, the magnetic coaction between magnets  142  and  144  urges the lever to rotate clockwise. These magnetic forces acting upon lever  102  will result in a requirement for an increased pressure to be exerted upon end  126  of trigger  100  before counterclockwise movement of the lever can come about. When it does, bowstring  111  will be released from jaw  108 .  
         [0052]      FIG. 15  illustrates a fifth embodiment of variant  90  shown in  FIG. 11 . In this embodiment, trigger  150  is secured to a first lever  152  by a bolt  154 . The first lever is pivotable about a pin  156 . Upon exerting a force on end  158  generally along the longitudinal axis of trigger  150 , lever  152  will rotate in a clockwise direction. Simultaneously, trigger  150  will rotate about pin  156  away from body  92 . A second lever  160  is pivotable about a pin  162 . End  164  of lever  152  bears against end  166  of lever  160 . Upon clockwise rotation of lever  152 , end  164  will bear against end  166  and cause lever  160  to rotate about pin  162  in a counterclockwise direction. Lever  160  includes an end  122  that is disposed within and bears against indentation  120  of jaw  108 . Upon pivotal movement of lever  160  in a counterclockwise direction, end  122  will become disengaged from end indentation  120  and jaw  108  will be free to pivot counterclockwise in response to the forces generated by bowstring  111 .  
         [0053]     Resistance to pivotal movement of lever  160  may be accomplished as follows. A magnet  170  is mounted in body  92  in proximity with a magnet  172  mounted in trigger  150 . The magnetic attraction between these two magnets will resist pivotal movement of trigger  150  about pin  156 . A magnet  174  may be mounted on lever  152  on a side of pin  156  opposite from trigger  150  to urge counterclockwise movement of the lever as a result of the magnetic force between the magnet and body  92 . Jaw  108  may include a magnet  176  magnetically cooperating with a magnet  178  mounted adjacent thereto at the upper end of lever  160 . These two magnets will cooperate to magnetically retain the upper end of lever  160  within indentation  122  of the jaw.  
         [0054]     In operation, movement of trigger  150  will not occur until a sufficient force is exerted at end  158  of the trigger to overcome the magnetic force between magnets  170  and  172 , between the magnetic force of magnet  174  acting upon body  92  and the magnetic force between magnets  176 ,  178 . When the sum of these forces is overcome, lever  152  will be caused to pivot clockwise by trigger  150 . Such pivotal movement will result in end  164  of lever  152  bearing against end  166  of lever  160  to cause lever  160  to rotate in a counterclockwise direction. Upon such rotation of lever  160 , end  122  will disengage from indentation  120 . Upon such disengagement, the force exerted by bowstring  111  will no longer be restrained by jaw  108  and the jaw will pivot counterclockwise to release the bowstring.  
         [0055]      FIG. 16  illustrates a second variant  180  of the magnetic release wherein a triggerless release is illustrated. Body  182  includes scalloped surfaces  184 ,  186  for engagement by the forefinger and middle finger of a user. A partial disc-like element  188  is mounted upon an arm  190  of body  182  by a pin  192 . A jaw  194  is pivotally mounted upon arm  190  by a pin  196 . The jaw includes a hook  198  for retaining a bowstring  200  therewith. Jaw  194  includes an indentation  202  for receiving an end  204  of element  188 . A magnet  206  is mounted in element  188 . The magnet provides a magnetic force to retain end  204  of the element within indentation  202 . A set screw  208  is employed to bear against element  188  to provide adjustment to the rotational position of the element relative to jaw  194 .  
         [0056]     The force exerted by bowstring  200  will tend to cause jaw  194  to rotate clockwise. Such rotation is resisted by element  188  in mechanical engagement therewith and is enhance by magnet  202 . By twisting body  182  clockwise, end  204  of element  188  will move out of engagement with indentation  202  to release jaw  194 . Upon such release, the jaw will rotate clockwise under force of bowstring  200  until the bowstring clears the end of the jaw. Thus, the second variant magnetic release shown in  FIG. 16  is triggerless.